WAVES 

Lecture notes 

Waves are of practical significance to us...they may swamp a small boat, smash supertankers, damage offshore structures, force commercial vessels to slow their speed, damage shore structures, make students skip school when they want to surf and determine what adaptations organisms along the shoreline must have in order to exist there.

Exposure to waves, tides, currents and pressure presents significant obstacles to the survival of animal and plants living in the ocean. Waves pound the shore, tides inundate and expose marine organisms severally restricting the distribution of seashore life.

Waves are mechanical energy that has been transferred from wind, earthquakes, landslides, or other waves to the ocean water.

Most of the transfer is by wind and waves travel outward from the energy source. As more energy is supplied, waves become larger.

Properties of waves

3 factors that determine size of wind generated waves.

1. time of contact

2. velocity of wind

3. fetch-distance over which wind is in contact with water.

Particles in the ocean are set into an elliptical motion as wind energy acts on water. The energy of the particles move (is transferred) through the ocean, not the particles. Their movement makes the waves shape.

The highest part of the wave is the crest, lowest is the trough, the distance between successive crests or troughs is the wave length, and the vertical height-from the top of the crest to bottom of trough is the wave height, the time between successive crests/troughs passing a fixed point is the period of a wave. Sharp peaks are called seas and as waves move out of their area, the crests become rounded forming a swell, a long, low wave that can travel thousands of miles.

As the wave approaches the shallow water, it changes shape. -the wave length decreases. -the height increases as particles encounter resistance from the bottom. -pathway of the particles become more elliptical as it gets closer to the coastline. -bottom resistance slows the waves. -shortens wave length when depth is 1/2 wavelength. When depth decreases less than 1/2 wavelength (or 1.3x height) the frictional drag along the bottom and forward motion of the wave and steepness of the crest causes the wave to break or collapse against the shore. Stored energy is released as the water falls against the shore.

Marine organisms along the ocean are affected by wave actions. Sandy and rocky shores, exposed to the direct assault of strong waves are known as a high energy environment, as opposed to beaches in protected estuaries, bays and lagoons which is a low energy environment.

Winter usually has higher crests and shorter wave lengths than summer thus release more energy on the shore.

Tsunami- a wave caused by undersea earthquakes near island arcs and trenches that make enormous waves. Energy is transferred to water as the coastal plates shift. Travel through the sea at 100+ mph with a wave length of 100miles when reaching the coast, wave lengths shorten and heights can increase to 100'. Krakatoa 1883 the wave moved around the world.

HOW A WAVE FORMS

To create a wave, a generating force is required. This is a result of a pulse of energy which produces waves (throw a stone etc.) The waves produced by the generating force moves away from the point of disturbance.

When the rock hits the surface, it disturbs and displaces the water surface. As the rock sinks, the displaced water flows back into the space from all sides and its momentum forces it upward resulting in a higher surface. The elevated water falls back causing a depression below the surface, which is filled and in turn sets up a series of waves that move outward and away from the point of disturbance until they are dissipated through friction among the water molecules.

The force that causes water to return to the level of undisturbed surface is the restoring force. This has to do with the surface tension (elastic quality of the surface due to the cohesive behavior of the water molecules.) This affects smaller waves, but larger waves are pulled back by the force of gravity and are called gravity waves.

The most common generating force for water waves is moving air or wind.

As the wind blows across a smooth water surface, the friction or drag between air and water tends to stretch the surface resulting in wrinkles. Surface tension acts to restore a smooth surface. The wind and surface tension create small waves called ripples or capillary waves. You can see these as wind moves over a smooth surface of a pond or lake, and are called cat's paws as they move across the surface keeping pace with the wind.

As the wind blows, energy is transferred to the water over large areas, for varying lengths of time, and at different intensities. As waves form, the surface becomes rougher, and its easier for the wind to grip the roughened water surface and add energy. There is an increased frictional drag between the air and the water. As the wind energy is increased, the oscillations of the water surface becomes larger and the restoring force changes from surface tension to gravity. A wave is a result of the interaction between a generating force and a restoring force. Generating forces include any occurrence that adds energy to the sea surface: wind, landslide, sea-bottom faulting or slipping, moving ships, and even thrown objects.

PARTS OF THE WAVE

The portion of the wave that is elevated above the undisturbed sea surface is the crest. The portion that is depressed below the surface is the trough. The distance between two successive crests or two successive troughs is the length of the wave or wavelength, and the height of the wave is the vertical distance from the top of the crest to the bottom of the trough. The amplitude is equal to 1/2 the wave height or the distance from the crest or trough to the still water or equilibrium surface. The period is the time required for two successive crests (or troughs) to pass a point in space.

While the dimensions and characteristics of waves vary greatly, the regularity in the rise and fall of the water's surface and the relationship between wavelength and wave periods allow math approximations to be made giving more insight to the behavior and properties of waves.

WAVE MOTION

The particles of water get set into motion when a wave passes across the water surface. The ocean wave does not represent a flow of water but a flow of motion or energy from its origin to its eventual dissipation at sea or loss against land.

As a wave crest approaches, the surface water particles rise and move forward. Immediately under the crest the particles have stopped rising and are moving forward at the speed of the crest. When the crest passes, the particles begin to fall and to slow their forward motion. It reaches a maximum falling speed and zero forward speed when the midpoint between crest and trough passes. As the trough advances, particles slow in falling rate and start to move backward until at the bottom of the trough they reach the maximum backward speed and neither rise or fall. As the remainder of the trough passes, the water particles begin to slow their backward speed and start to rise again, until the mid-point between the crest and trough passes.

Now they start their forward motion and continue to rise with the advancing crest. The motion creates a circular path or orbit for the water particles. This is the motion that causes a boat to bob!

The surface water particles trace an orbit whose diameter is equal to the wave height. The same motion is transferred to the water particles below but less energy of motion is found at each succeeding depth. The diameter of the orbits decrease and become smaller and smaller as the depth increases. At a depth of 1/2 the wavelength, the orbital motion has decreased to almost zero.

All this is based on sine waves and while in the ocean, there is a bit of difference because due to real waves, the crests are sharper than the troughs so there is minimal transport of water in the direction of the waves, the motion is often ignored when studying waves.

WAVE SPEED

It is possible to relate the wavelength and period of the wave in order to determine the wave's speed. The speed of the wave (C) is equal to the length of the wave (L) divided by the period (T):

Speed = length/period or C=L/T

While the period of the wave is not hard to measure at sea, the wavelength is because of no fixed reference point. So the oceanographer determines the period (T) and calculates the wavelength (L) by another equation.

In deep water, the wavelength is equal to the acceleration due to gravity (g) divided by 2p times the square of the wave period (T). The value of the earth's gravity (g) is 9.81 m/sec²

L=g/2p (T²)  or  a simpler  one .....L(in feet)=5T^{2  or}  .L(in meters)=1.5T²

^interesting!

DEEP-WATER WAVES

Deep water waves must occur in water that is deeper than 1/2 the wave's length so in order for the waves to behave like the description below, it must be a deep water wave.

STORM CENTERS

Most waves at sea are progressive wind waves. They are build up by the wind, restored by gravity and travel in a particular direction. These waves are formed in local active storm centers or by steady winds of the trade wind and westerly wind belts. An active storm may be large, with unsteady winds and varying directions and strength. The winds in the storm flow in a circular pattern around the low-pressure storm center creating waves that move outward and away from the storm in all directions. In the storm center, the sea surface is jumbled with waves of all heights, lengths and periods. There are no regular patterns. Sailors call this a sea. As waves are being generated, they are forced to get larger by the input of energy forced waves. Due to variations in the winds of the storm area, energy at different intensities is transferred to the sea surface at different rates, resulting in waves with a variety of periods and heights. Once a wave is created with its period, the period doesn't change. The speed may change but the period remains the same. The period is a constant property of the wave until the wave is lost by breaking at sea, through friction, or crashing against the shore.

SWELL

Once energy or generating forces no longer effect the waves, the forced waves become free waves moving at speeds due to their periods and wavelengths. Some waves produced have long wavelengths and long periods and have a greater speed than those with short. They gradually move through and ahead of the slower ones and escape the storm and appear as a regular pattern of undulating crests and troughs moving across the sea surface. Once away from the storm these waves are called swell. They carry considerable energy which they lose very slowly..

The movement of the faster through and ahead of the slower waves is called sorting or dispersion. Groups of these faster waves move as wave trains or packets of similar waves with about the same period and speed (sets).

WAVE INTERACTION

Waves that escape, or outrun a storm are no longer receiving energy from the storm winds and tend to flatten out slightly and the crests become more rounded. As they move out across the ocean, they are likely to meet other trains of swell moving out and away from other storm centers. When two wave trains meet, they pass through each other and continue on. Wave trains may intersect at any angle, and many possible sea surface patterns may result. If 2 trains intersect sharply a checkerboard pattern will be formed, and in some cases two or more trains may phase together so they suddenly develop large waves unrelated to any storms that may become so high they break losing some of their energy.

WAVE HEIGHT

While table 8.1 shows typical wind waves in deep water and their sizes compared to the wave length etc., there are several factors that influence the height of a wave.

1. wind speed

2. wind duration

3. fetch ( distance over water that the wind is blowing in a single direction.)

Any one of these factors can limit the wave height. If the wind speed is low, it doesn't matter how far and how long the wind blows over the water, no large waves will be produced. If the wind speed is great but short, again, no large waves will be formed and strong wind over a short area will also not produce large waves. When no single limiting factor is present, large waves can form at sea. (40-50' S).

A typical fetch for a local storm is about 500 miles and with the storm moving, and the storm winds circulation around the low pressure area, the winds can continue to follow the waves on the side of the storm which increases fetch and duration of time over which the wind can add energy to the waves. Waves up to 49feet are not uncommon and the wave lengths can be between 330-600feet.

Wave heights taken in the North Atlantic over the past 25 years show a continuing increase in wave height of about 25%. There is no known reason for this increase.

Giant waves over 100' are rare but a Navy Tanker (USS Ramapo)in 1933 encountered a Typhoon and riding on the downside to ease the ride, was overtaken by waves that when measured against the ships superstructure by the officer on watch were 112'high. The period was 14.8 seconds and the wave speed was 90'/sec (60 mph). While conditions to produce waves of this size occur, none have been well documented (or have survived).

EPISODIC WAVES

Large waves that suddenly appear at sea unrelated to local conditions are called epsodic waves. It occurs due to the combination of intersecting wave trains, depths and currents. Not much is known and when they do occur and swamp ships, witnesses are often removed. They occur near the continental shelf in water about 600' deep and in some areas with prevailing wind, wave and current patterns. (Agulhas Current) p220

WAVE ENERGY

Waves carry considerable energy per each unit width of their crest. The unit is measured in meters or unit width of 1 meter. The wave represents a flow of energy and its present as potential energy due to the change in elevation of the surface water, and kinetic energy due to the motion of the water particles in their orbits. The higher the wave, the larger the diameter of the water particle orbit and the greater the speed of the orbiting particle so the greater the potential and kinetic energy. The wave energy is calculated in a fun math formula and represented in fig. 8.8 basically showing that it increases greatly.

Energy average over one wavelength per unit width of crest from the sea surface to a depth of L/2 and related to the square of the wave height.

WAVE STEEPNESS

There is a maximum height for any given wavelength. This value is determined by the ratio of the wave's height to the wave's length and is the measure of steepness of the wave:

Steepness = height/length or S=H/L

If the height to length ratio exceeds 1:7, the wave is too steep, the crest angle will be sharper than 120' and the wave is unstable and will break. A wave length of 70m will cause a wave to break when it exceeds 10m (1:7).

Whitecaps have very short wavelengths(about 1m) and break because the wind increases their height rapidly...quicker than the wavelength increases. Also when wave trains pass through each other, he quick increase in height can cause these waves to break (even in the middle of the ocean).

Waves sometimes run into a strong opposing current which forces the waves to slow down. Remember the speed =L/T and once a wave is formed, the period doesn't change. so its wavelength will shorten if its speed is reduced so the wave will increase in height to satisfy the direct height-energy relationship. If the increased height exceeds the max. the wave breaks. (entering harbors etc during outgoing tides).

Beaufort Wind Scale p223

SHALLOW WATER WAVES

When the deep water wave begins to approach the shore and shallow water, the reduced depth begins to affect the shape of the orbits. They become flattened circles or ellipses and the wave begins to "feel" the bottom and the resulting friction and compression of the orbits reduce forward speed of the waves. Remember the speed of the wave is equal to the wavelength divided by the period and 2. the period never changes so when the wave slows because it feels the bottom, there is a reduction in wavelength resulting in an increase in wave height and steepness.. When the wave enters water with a depth of less than 1/20 the wavelength the wave becomes a shallow-water wave. The speed is now determined by the square root of the product of the acceleration due to gravity (g) and depth(D): c=`/gD

When the water depth is between L/2 and L/20, the speed of the wave is also slowed. Waves in this depth range are called intermediate waves. (no simple way to determine speed).

REFRACTION

Waves are refracted or bent as they move from deep top shallow water and begin to feel the bottom. Waves usually approach the shore at an angle and when one end of the crest comes in and feels the bottom and the other end is still in deeper water, the shallow water end slows and because the deep water part is still traveling the same speed, the wave crests bend, or refract, and tend to become orientated parallel to the shore.

When waves approach an irregular coastline, certain refraction patterns occur. Waves will slow over submerged ridges and speed over submerged canyons.

REFLECTION

A steep, vertical barrier in water deep enough to prevent waves from breaking will reflect the waves.. The barrier may be a cliff, steep beach, breakwater, bulkhead or other structure. Waves approaching this barrier at an angle reflect from the barrier at the same angle. These pass through incoming waves to produce an interference pattern and often steep, choppy seas often result.

DIFFRACTION

When a wave passes its energy though a narrow opening, some wave energy will pass through to the other side and once through the energy radiates out and away from the gap. A portion of the energy is transported sideways from the original wave direction it is diffracted. Energy can be transported sideways and around the end of a barrier and energy can be transported behind the barrier but much is lost.

THE SURF ZONE

The surf zone is the area along the coast in which the waves slow, steepen, break, and disappear in the turbulence and spray of expended energy. The width of the zone is related to the length of the arriving waves and changing depth pattern.

BREAKERS

Breakers are formed in the surf zone because the water particle motion at-depth is affected by the bottom, slowed down, and compressed vertically. The orbit speed of the particles near the crest are not slowed too much so particles move faster toward the shore than the wave itself. The crest can curl and eventually break (fall over). There are two types, plungers and spillers.

Plunging breakers are usually found on a steep beach, the curling crest outruns the rest of the wave curves over the air below it and breaks with a sudden loss of energy and a splash. Spilling waves occur at flatter beaches and consists of turbulent water and bubbles flowing down the collapsing wave face.

WATER TRANSPORT

Waves transport water toward the beach in the surf zone. There is a drift of water in the direction the waves are traveling and is intensified in the surf zone and with the waves approaching the beach at an angle, the transport of water moves both toward and along the beach. This water must flow seaward again and will in a quieter zone with smaller waves. Because these regions may be some distance apart, and narrow, the water may flow out quickly forming a rip current.

TSUNAMI

Earthquakes are often responsible for producing seismic sea waves or tsunamis. They are called tidal waves (incorrectly) and formed if in an area the earths crust suddenly raised or lowered. The displacement causes a sudden rise or drop of the sea level and gravity causes the water to quickly fill it in. Waves with long wave lengths are produced (100-200km) and periods of 10-20 min. Since the aveg. depth is 4000m it is less than 1/20 the wavelength so it acts like a shallow water wave. Because of this they may be refracted, diffracted, or reflected in mid-ocean.. p230

STORM SURGES

Periods of excessive high water due to changes in the atmospheric pressure and the wind's action on the sea surface are called storm surges or storm tides. These are not typical waves but share characteristics of curving sea surfaces and produce like effects to that of tsunamis.

Chapter Questions

Questions for Tsunami Reading

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TIDES

Lecture notes 

The rhythmic rise and fall of the oceans water at a fixed location is known as the tide. Changing water levels create hardships for coastal organisms by exposing them. Tides are long waves moving through the ocean. When the crest of the moving tide reaches a location, high tide occurs. Low tide is when the trough reaches the location.

Best known as the rise and fall of these around the edge of land, the tides are caused by the gravitational attraction between the earth and the sun and between the earth and the moon. While tides go unnoticed far out at sea, they are easily observed along the shoreline.

TIDE PATTERNS

Three types of tides occur.

• 1. Semi-diurnal 2 high and low tides per day about equal range. Most.EC
• 2. Diurnal 1 high and 1 low tide per day (24hrs) Gulf of Mexico/Vietnam/Manila
• 3. Mixed 2 high and 2 low tides per day but different ranges...1 high high, 1 low low 1 high 1 low west coast

Tides behave differently in different places. In some coastal areas there is a regular pattern of one high and one low tide each day known as a diurnal tide. In other areas there is a high-low water sequence repeated twice a day...semidiurnal tide and these tides usually reach about the same level at high and low tides each day. The third type of tide has two high and low tides a day but the tides reach different high and low levels during a daily rhythm. This is called a semidiurnal mixed tide. It is caused by a diurnal (daily) inequality by combining a semidiurnal and diurnal tide. Tides are charted on a marjoram which shows the height of the tide above mean low water (sea level) and the time of the peaks of the high/low tides.

In the uniform tidal system (semi and diurnal) the greatest height to which the tide rises on any day is known as high water and the lowest point is low water. In a mixed system it refers to higher high and lower high water and higher low and lower low waters.

Tidal observations made over a period of time are used to calculate the average or mean tide levels.

Since the depth of coastal waters is important for navigation, an average low-water reference is established: depths are measured from this level and recorded on navigational charts. This area is usually established at mean low water and the zero reference or tidal datum, is established at this point. In mixed tidal areas, mean lower low water is used as the tidal datum. Sometimes the low tide level may fall below the mean value used as the tidal datum producing a minus tide.

When the tide is rising, it is called a flooding or flood tide and when its falling it is an ebbing tide.

TIDAL CURRENTS

Currents associated with the rising and falling of the tide in coastal waters is a tidal current. They can be very swift and dangerous. When the tide turns, reverse direction, there is a period of slack water during which the tidal currents slow and then reverse.

TIDAL THEORY

0ceanographers analyze tides in two ways. One is using universal laws of physics called equilibrium tidal theory and the other is studying them as they occur in nature called dynamic tidal analysis which study the oceans tides as they occur modified by the land masses, geometry of the ocean basins and earth's rotation.

The effect of the sun and moons gravity on tides is easily explained using the equilibrium theory. 9.3 A water covered planet with its satellite moon orbits the sun. The moon is held in orbit about the earth by the earth's gravitational force (B). There is also a force pulling the moon away from the earth and send it spinning into space (B') and is considered centrifugal force in this discussion. The earth and moon are held in orbit by the gravitational attraction between the center of mass between the moon and earth system and the sun (A). The centrifugal force pulls the center of the mass away from the sun (A'). To stay in orbit A must equal A'. (like twirling a string with a weight on it around your head and the string is gravitational attraction.

In the earth moon sun system, the mass of the sun is great but its very far away and while the mass of the moon is small, its closer and therefore has a greater attractive effect on water particles than does the sun, so the moons effect will be considered first because its greater.

MOON TIDE

Water particles on the side of the earth facing the moon are closest to the moon are acted on by the larger moon gravitational force and because water is liquid and deformable, the force is applied to water particles toward a point directly under the moon. It produces a bulge in the water covering. At the same time, the centrifugal force of the earth moon system acting on the water particles at the earths surface opposite the moon creates a bulge too. Now a model would show 2 bulges on opposite sides of the earth but that is on a uniformly deep water covered planet.. The area between bulges (opposite each other) would be low water areas or depressions (or 2 crests and two troughs--high tide and low tide).

TIDAL DAY

The moon and earth are moving in the same direction along its orbit during a 24 hr period but the earth must turn an extra 12' or 50 minutes for the moon to be directly over the same place. Therefore the tidal day is not 24 hours long but 24 hr and 50 minutes explaining why tides arrive at a location about an hour later each day.

TIDE WAVE

The equilibrium tides produced are semidiurnal or two high and two lows a day. The tidal distortion of a models water covering produce a wave form known as the tide wave. The crest of the wave is high water ( tide) and the trough is low water (tide). The wavelength of this wave is 1/2 the circumference of the earth and period 12 hr and 25 min.

The SUN TIDE

While the moon plays a greater role in tide producing, the sun also produces its own tide wave. Though it is large, the long distance away means its tide raising force is only 46% that of the moon and the average time is 24 hours not 24h50m. The tide wave produced by the moon is greater magnitude and continually moves eastward relative to tide wave produced by the sun and therefore the tide forces produced by the moon are greater and more important than that of the sun (therefore tidal day 24h50m).

SPRING AND NEAP TIDES

During the 29 1/2 days it takes the moon to orbit the earth, the sun, the earth and the moon move in and out of phase with each other. During the period of the new moon, the moon and sun are lined up on the same side of the earth so that the high tides, or bulges, produced independently of each, coincide. Since the water level is the result of adding the two wave forms together, tides of maximum height and greatest depression, or tides with the greatest range between high and low water are produced. These are spring tides. The vertical displacement of the tide may also be described as amplitude or 1/2 the range (distance above or below sea level.)

In a weeks time, the moon is in its 1st quarter and moved about 12' per day, until its at a right angle to the sun wave. Now the crests of the moon tide will coincide with the troughs produced by the sun and the same is true of the sun's crests and moons troughs. They tend to cancel each other out and the range between high and low water is small. These are low-amplititude neap tides.

At the end of another week, the moon is full and the sun, moon and earth are again lined up, producing crests that coincide and tides with the greatest range between high and low waters, or spring tides. These are followed by neap tides seven days ;later and the cycle, 4 weeks, continues with a spring tide every two weeks...etc. This 4 week progression creates a tidal cycle of changing tidal amplitude.

DECLINATION TIDES

If the earth and moon are aligned so that the moon stands north or south of the earth's equator, one bulge is in the Northern Hemisphere and one in the Southern Hemisphere. A point in the middle latitudes passes through only 1 crest and one trough during the tidal day. This type of diurnal tide is called a declination tide, because the moon is said to have declination when it stands above or below the equator.

The sun also influences these tides as it sits over 23.5N/S at summer and winter solstice and the variation causes the bulge created by the sun to oscillate north/south (making a more diurnal sun tide during winter and summer. The moons declination is at 28.5N/S and because the orbit is inclined 5' to the earth sun orbit, it takes 18.6 yrs for the moon to complete its cycle of max. declination. When the sun and moon coincide, both tide waves become more diurnal. Also the moon doesn't move around the Earth in a perfectly circular orbit or even does the earth circle the sun at a constant distance. In the Northern Hemisphere, the earth is closer to the sun so the solar tides play a greater role as a tide producer in the winter than summer. see p254 tide charts

TIDE TABLES

Because of all the combinations, its not possible to predict the earths tides from our knowledge of tide raising bodies alone. But with a combination of actual local measurements with known astronomical data, tide predictions are quite accurate.

Water level recorders are installed at coastal sites and the rise and fall are measured over a period of years...at least 19 years are needed to allow for the long 18.6 year period of declination of the moon. Tide Tables are published annually by NONA. The tables give the dates, times, and water levels for high and low water at a primary tide station. There are only 196 of these but consulting a list for other 6000 auxiliary stations applying corrections to the times and heights of the primary stations helps more localities get accurate tide predictions.

Tidal predictions are based on recorded high measurement from past records which are used in the future.

Tide Current Tables

Like tides, these currents are measured at primary locations and data is published similar to tide tables. Useful for moving in and out of estuaries.

Summary
Without land, 2 bulges , 1 on side of the earth closest to the moon, 1 on the other side would appear. Bulge is high tide from mutual attraction between earth and moon. Moon gravitational attraction pulls and moves the water. The opposite bulge, centrifugal (I know, there is no such thing, ) force created as the earth and moon revolve around a common point...barycenter-4670 km (2900miles) from earths center.

Tides occur at different times because the moon goes around the earth in 24h50m or 1 lunar day. (freq 12h25m)

Due to friction between earth and tidal bulges, High tide is given about 50 minutes after the moon passes over that point. known as a lunar semidiurnal tide.

Vertical height ...high to low water is the tidal range and varies day to day because of the sun and the moon. Solar tides are 1/2 the size of lunar tides. When the sun and moon line up (2x per month) tides are higher and lower than usual...spring tide. When the moon is at right angles to the sun, there is less gravitational effect that lessens the tidal range (neap tides) Between these tides the height varies throughout the month.

Differences in tidal frequencies and range occur because of the shape of the ocean basins and coastline (Hawaii is a few cm while the Bay of Fundy is 20m.

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Lecture Questions

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SANDY BEACHES

Lecture Download 

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Sand Dune Page

video of African beach

The sand beach is a hostile environment, forming a boundary between the ocean and the land . The beach is subjected to harsh conditions such as breaking waves, changing tides, salt laden winds, extreme temperature changes etc. The sand beach is a temporary habitat.

The texture changes seasonally. Winter beaches contain course sediments while summer beaches contain fine sediments. The removal of beach sediment is erosion and addition of material is deposition. The changes in steepness is the slope.

The beach is a region between the high and low waterlines that is covered by sand or some other unconsolidated material.

Some materials along the coastline are more susceptible to weathering than others. Granite, a crystaline rock, is much more resistant to erosion than sandstone. Regions made of sand are quite susceptible to erosion. Quartz sand is common in beaches along the continental shorlines (Gulf from Tampa to Pensacola almost pure quartz sand) La Jolla, the oxidation of iron in mica give the sand a gold cast and the high iron and magnesium content in some sand account for dark patches seen on beaches especially in winter when heavy sediments are left behind while lighter quartz is removed by larger winter waves. Some sand in many tropical and subtropical beaches is predominantly calcium carbonate secreted by marine organisms (shells, algae coral) and in Hawaii and Iceland, black beaches from basalt lava are common. Minerals like gold and diamonds have been found in certain areas of the world on the beaches.

Tides produce short-term fluctuations along coastlines but sea level changes are long-term. Tsunamis have changed coastlines.

Turbulant waves along the shore usually remove mud from the beaches and hold it in suspension. As the fine particles of mud are transported to deeper or less turbulent water, they settle on the bottom. A beach is described in terms of the average size of its sand particles, the range and distribution of these particles, the elevation and with of the berm, the slope of the foreshore and the slope of the inshore. Generally the larger the sand particles, the steeper the beach.

Waves are primarily responsible or moving sand away from river mouths and along the coast. As a wave breaks, the sudden release of energy within a small area causes turbulence that dislodges sand particles. If waves moved in perpendicularly to the beach, then the particles would only move in and out. However, waves approach the coast from almost any angle and if it comes in from the north say, then the water runs back to the sea in a southernly direction. This forms what is known as the longshore current or littoral drift. This current provides longshore transport that carries sand along the shore. Beach sand is always in transit from one place to another. Size and power of waves affect the rates of longshore transport. On the east and west coast, LST runs in one direction usually, and thats south because most waves come from northern storms. Sand is transported south at a rate of 150,000 to 1,600,000 m3/yr.

Large scale earth movements...well an earth quake or the collision coasts where two plates run into each other can affect the coast, but thats covered in plate tectonics.

Human activities have had both benificial and harmful effects on the coastline. Damming of rivers, land recovery programmes, dredging of inlets, development of dune areas and construction of erosion control structures.   

Dams-when a river is dammed, deposition occurs upstream of the dam instead of at the river mouth where coastal currents could carry he sand down the beach starving the currents and causing erosion of the beach and coastline.

Land recovery-in the Netherlands, this expensive way to get land has destroyed sensitive marsh lands which were regions of life.

Dredging Inlet dredging has become popular so boats can go out into the ocean. Here each area can be looked at. San Diego bay when dredged did not have any real effects on the area while the dredging of a channel in Matanzas Inlet in fla (st Aug.) to enhance land values at Crescent beach and Marineland, had disastrous results. The tidal currents rushing from the new channel, have diverted the strong longshore current,causing sediment to be deposited on the inlets north side and the starved current sweeps by the south side eroading the shorefront property and highway to boot!

Erosion Control Structures  

Jetties built to prevent longshore currents from filling inlets or to bring about the deposition of sediments benefit the property immediately upcurrent but may cause the downcurrent shoreline to recede. Groins, small piles of rocks at right angles to the beach transform the longshore current into a zig zag current that destroys the linear form of the coast. Wherever it encounters nonresistat rock, it erodes the shore.

The precarious stability of the shoreline and of the transition zone between the nonmarine environment and the delicate matrine environment suggests that the shoreline should be left undeveloped except where development poses no hazards. Developers should consider the long term consequences of massive shoreline development programs before proceeding.

THE SHORE

The shoreline is the region bounded by high and low tide and by the farthest landward reach of the waves.

The backshore is the area of the shoreline above the high water or high tide mark. This can contain cliffs or sand dunes or a berm (flat upper beach).

The foreshore is the area that is exposed at low tide. It may have a beach scarp (vertical slope produced by wave erosion) and a low tide terrace (broad flat area exposed at low tide.

The offshore region extends from the low tide mark seaward beyond the wave breaking zone. It has a shoreface (slope below the low tide mark) and a longshore trough (a depression parallel to the beach between the low tide mark and wave breaking zone).

Longshore bar is a sand ridge parallel to the beach.

5 factors interact along the coastline:

• rock materials present along the shore
• changes in sea level
• the energy of certain natural processes
• large-scale earth movements
• and human activities.

Zonation.

Boundries are difficult to locate because of shifting sand and changing heights of waves.

Upper beach-supratidal zone ranges from high tide mark to sand dunes. Animals live below the sand to avoid sunbaked surface. The sand contains almost no food or water so the animals feed at the surface. The most common animals in this zone are amphipods called sand fleas, which are found under driftwood and seaweed during the day. A crustacean, the ghost crab, also lives here and both animals consume dead plant and animal material. This is the fastest crab and blends in with the environment. It breaths air but must return to water to moisten gills and casts fertilized eggs into the surf where they develop as drifting larva in the ocean and return to the beach when they grow. These are consumers of decaying plant and animal material and sea turtle eggs. Some insects and plants also live here but also live in the dunes so fall under sand dunes. At night, insect eating bats, rats, mice run along the tide mark searching for food.

Strand-line. highest place where the ocean washes the beach. This area collects stranded material called beach wrack which provides a cool, moist environment for small invertebrates (biting fleas, centipedes, earwig beatles, amphipods.). Gulls and sandpipers scavenge here and whats left, bacteria breaks down. The organic materials provide food for scavengers and decay bacteria break down the rest to release nutrients_ back into the ocean for the primary producers to use thus completeing the cycle of life.

Intertidal zone:

• 1. Exposed to atmosphere at low tide, covered at high tide...
• 2. absorbs direct assult of waves.
• 3- sands shift, grinding organisms.

The surface remains wet at low tide from capillary action. Sand grains stay wet and draw water up towards the surface to evaporate. Organisms can now thrive near the surface of the sand. These organisms belong to the interstitial sand community which vary from minute bacteria to worms and copepods.The bodies of these are thin and long and can move easily among the grains. They have adhesive organs allowing them to stick to grains and not be washed away. Diatoms and dinoflagellates are the main producers living in the sand and can migrate deeper and shallower in the sand.(color the sand). There are great quanities of detritis for food and consumers from protozoa to annelids to nematodes which can number 2-3 million per meter2

Subtidal zone..from the lowest part of the intertidal zone to as far out as sand is moved by wave action. Environmental factors change slowly but there is still no substrate which means living under the sand. Fish have adapted a burrowing lifestyle (eels, flounders, soles, rays, skates.) The number of species living in this soft-bottomed subtidal zone usually outnumbers the number of species on the soft bottom of the intertidal zone because of the stability below the low tide mark. Desiccation, rapid temperature changes, salinity variations are not as much a problem.

While the zonation is not as easily seen as on rocky shores, it does exist in ernst but is usually absent from muddy water where there is no change between high and low water marks.

These soft bottoms are unstable and constantly shift in response to waves, tides and currents so the soft-bottomed organisms don't have a solid place to attach. Very few seaweeds/plants adapt to this (except seagrasses) so most of these organisms will burrow in the sediment to keep from being washed away. These are called infauna. T he kind of sediment on the bottom, size of grains etc have an effect on the kinds of organisms living as infauna. Sizes of grains/rub between fingers/gritty = sand...silt and clay are smooth (mud)...silt and clay clay is smooth between teeth and silt gritty! Yum

Living in the sediment has advantages in the intertidal. The soft bottoms hold moisture when the tide is out so desiccation is not that much of a problem. However, the corser the sand, the quicker it dries out! Also because of the lack of plants, oxygen availability is a main concern to the organisms living in the sediments. Also, most are detritus/deposit feeders because of lack of plants and this environment is also home to decay bacteria to help break down sediments (detritus) and these also use oxygen. The finer the sand, the more stuff it holds (more smelly) and courser, the less and therefore cleaner. Water flow through the fine sediments is restricted therefore, less oxygen circulation. The interstitial water is deficient of oxygen. This anoxic or anareobic condition is usually no problem to many bacteria (giving off hydrogen sulfide), but the animals must pump water from above the sediment and have developed long tubes for this.

Sand Dunes

Development of Dune areas

The commercial development of dune areas has also deterioated the ecology. Dunes are impermanent formations that rarely survive the building of houses and other structures. As the dunes are destroyed, the shoreline migrates deeper into the land.

Sand Dunes

Coastal dunes form where sand is deposited onshore by the sea at river mouths, or exposed by a dropping sea level as in past glacial times, dries out and is blown landward by the wind. (Tinley, 1985)

Coastal dunes exhibit unique processes of genesis () dynamics and zonation determined by the fluctuating sand supply/wind energy ratios related to daily, seasonal and long term changes in sea level and climate, soil changes and plant succession and exposure to salt spray.

Dunes are a mobile physical medium and ecological environment, frontal dunes are part of sediment exchange, increase in age and complexity as it gets farther from the coast, and contains an endemic and/or specialized plant and animal community.

• Dune- Hill, mound or ridge of sand composed of particles transported and heaped up into accumulations by wind.
• Dune Base--compact base of dune
• Dune Trough- linear depression between dunes
• Slack or swale- a seasonally or perennially wet depression between dunes.
• Hollow- a dry depression between dunes.
• Primary dunes The first line of dunes
• Secondary dunes The second line of dunes leading to the forrested area

There are 7 determinats to dune development along a coast.

• 1.wind regime
• 2.sand supply
• 3.degree of coastal exposure and deflection of winds
• 4.rainfall
• 5. plant colonization
• 6. sea (wave action and longshore drift)
• 7. river mouth dynamics.

Coastal dunes are populated by plants and animals that are exposed to hot blasts of salty wind, scorching sunlight and almost no water, meager food supplies, little or no firm footing, and wind blown sand.

Dune plants-few specialized plants can live on the upper beach and adaptations include; waxy coverings on the leaves, large root systems, small leaves and few stomata, thick stems and leaves to store water.

How do each of these adaptations help? List them!

Sand Dune Formation...an essay

Sand dunes form along the coast as sand is blown away from the beach. Grain by grain, the dune grows as onshore winds slow and drop their load of fine, sugary sand. The growth of coastal dunes begins as wind_movement across the open beach is obstructed by blades of grass, a fence etc. Dunes grow and gradually move inland away from the beach. The windward side of the dune usually has a gradual_slope because wind velocity slows and deposits sand along the face of the dune. Strong winds often carry sand over the crest and falls abruptly behind the dune where wind speed is much less. A steep slope forms on the backside of the dune. The first line of dunes are primary dunes which deflect ocean breezes and create a semi-protected environment on the backside of the primary dune. Plants that can't withstand direct blasts of salty wind on the dune face, grow in the protected lee of the primary dune. The area behind the primary dune is the swale which because of the deflection of the wind by primary dunes, can heat up to temperatures of 50'C. The second line of dunes, secondary dunes, are often thickly vegetated, which allows a coastal forest to often develop behind it.

Dune development/ fences to collect sand and walkover to protect the dune grass

Beach Comparisons

 Keys

Gulf

Gulf

    Gulf

   Atlantic

Atlantic

Atlantic

   Atlantic

  Atlantic/Indian

    Indian

Summary

Sand Beaches

What to look for: zonation, environment, Composition, Ecology of Dunes, formation of barrier Islands, Populations of beaches and TERMS

One-Line Glossay

Beach and Sand Lab

• BEACH
• COURSE AND FINE SEDIMENTS
• EROSION
• DEPOSITION
• SLOPE
• UNCONSOLIDATED MATERIAL
• LONGSHORE CURRENT
• SHORELINE
• BACKSHORE
• FORESHORE
• OFFSHORE
• SHOREFACE
• LONGSHORE TROUGH
• LONGSHORE BAR
• SUPRATIDAL ZONE
• STRAND-LINE
• INTERTIDAL ZONE
• INTERSTITIAL SAND COMMUNITY
• SUBTIDAL ZONE
• INFAUNA
• DUNE
• DUNE BASE
• TROUGH
• SWALE
• HOLLOW
• PRIMARY AND SECONDARY DUNES
• WIND/SAND/DEGREE OF COASTAL EXPOSURE
• RAINFALL/PLANTS/SEA/RIVER MOUTH

Beach Readings

Beach Reading Questions

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THE CORAL REEF SYSTEM

 

Lecture Notes

 

 

Single coral reefs may cover over 100 sq km: massive structures that have been built almost entirely by marine plants and animals. The material of the reef is calcium carbonate: limestone derived from the surrounding waters by the reef organisms. The living reef forms the top layer of the reef adding new limestone to these massive structures at rates that can be measured annually at KG's for every square meter of the reefs surface.

The corals are probably the most obvious life forms on the reefs. All the different colors and shapes made up of thousands of individual polyps, each secreting its own small cup of coral limestone, which provide the building blocks for reef construction. But plants are also important in the development of this system as many secrete limestone! Coralline algae, in particular, form cementing crusts that act as 'mortar' for the coral 'blocks'. Innumerable other plants and animals also contribute, forming fine sand and courser skeletal material which ends up as either sediments on the reef surface or as infill in the many cavities that develop within the reef.

Coral reefs have existed in the earth's shallow seas for a long time, probably in excess of 450 million years; a clear indication of how successful a life form they are. Although the original corals, called 'rugose' corals, became extinct about 200 million years ago, the reef that they formed were probably very similar to modern coral reefs.

HISTORY

The scleractinian corals that succeeded the rugose forms probably evolved in the warm waters of the Tethys sea, a massive ancient ocean that existed between the northern European and Asian land masses and the Southern African and Indian continents. It was eventually closed by the gradual northward migration of the southern continents, a process known as continental drift. The closing was earliest in the west and latest in the east so that the evolving corals were slowly pushed eastwards into the shallow peninsulas and island studded seas of the western Pacific. It is in this area which has by far the greatest diversity with more than 500 coral species known in this region.

The worlds modern reef's systems began to develop during the tertiary period (about 25 million years ago). Reefs have existed and grown successfully many times in the past. This explains why there are reefs and fossils in cold water areas of the world.

The Australian continent was also on the move and slowly drifting northwards from the cold polar latitudes and into the warmer waters of the tropics and by chance ventured into this area rich in coral growth...its northeastern shores in particular were bathed in the ocean waters passing through the coral rich seas. (great Barrier Reef)

With the great environmental fluctuations in the earth's history, sea levels have oscillated from positions slightly higher than the present to at least 150m below the present level. Corals and associated life forms were able to survive these changes showing how resistant to natural disturbances this ecosystem is.

Florida is the only state in the Continental US to have extensive shallow coral reef formations near its coasts. The reefs extend from near Stuart on the Atlantic east coast to the Dry Tortugas, west of Key West in the Gulf of Mexico. The best reef development occurs in the Florida Keys. These reefs may rival some of the Caribbean areas and number about 6000 between Key Biscayne and the Dry Tortugas.

These reefs came into existence 5-7000 years ago when the Wisconsin Ice Age ended and the sea level rose. The growth is slow and estimates range from one to 16' every 1000 years.

Live-bottom biota's

WORM REEFS Aggregations of the tropical reef worm (Phragmatopoma lapidosa ) construct low reefs of tubes consisting of sand grains cemented together by protein. The reefs expand as worm larva settle on existing tube masses. The reef growth is controlled by waves bringing planktonic food and sand to the worms. Found from Cape Canaveral to Key Biscayne and best developed off St. Lucie and Martin Counties...Bath Tub Reef.

Oculina Banks

Coral banks that occur offshore from JAX to St Lucie inlet at depths of 50-100m are another of FLA little known reef types. The banks are constructed by the ivory tree coral (Oculina varicosa).

GEOLOGY The Fla.-Bahamas region is part of an extensive carbonate platform that once extended into the Gulf coast region. The Florida platform is a massive southward-thickening wedge of limestone's that is at least 6000 m thick beneath Cay Sal Bank. These limestone's have been accumulating for about 150 million years. About 15 million years ago, cooling occurred in the northern latitudes, climates cooled and sea levels began to drop...coral reefs retreating to lower latitudes...and during the past million years with each continental glacial advance, sea level dropped further and coral reef communities withdrew from Florida. During interglacial episodes, sea level rose, waters warmed, and corals returned. The Key Largo Limestone , a fossil coralline rock found in the upper keys, provides evidence of coral reef development during the last glacial period before the present. This formation extends from Miami to the dry tortugas and into the straits of Florida. It varies in thickness from 23m to 61m. the last glacial period ended about 18000 yrs ago and sea level began to rise. Modern reef development began about 5000-7000 yrs ago.

Stony corals are the major reef architects. These small marine animals, called polyps, remain in one place throughout their adult lives and produce a hard skeleton made of calcium carbonate, which they extract from the seawater and combine with CO2 for limestone, constructing elaborate limestone skeletons which are left behind when the animal dies. Some corals grow in colonies that continue to enlarge year after year, and some are solitary and live alone. Together they can form enormous colonies that are called coral reefs, coral islands and coral atolls. The largest, being the GBR, is 1,250 miles long. They can exhibit many shapes, sizes, and colors and reefs look like underwater gardens (although they usually lose their colors when removed from the water except red coral). These shapes and patterns are characteristic for the species and are a result of growth patterns of millions of tiny individual polyps that make up the colony.

And though reef corals are classified as animals, there is a complex of microscopic plants called zooxanthellae, which live within the animal tissues (symbiosis) and the animals benefit from the energy that the plants provide through photosynthesis. These dinoflagellates gain nutrients from the corals nitrogen and phosphorus wastes. They are also responsible for most of the colors of the reef.

These specialized habitats provide shelter, food, and breeding sites for numerous plants and animals and form a breakwater for the adjacent coast, providing natural storm protection. They are also important to SE Fla's economy.

Reef development occurs only in areas with specific environmental characteristics:

1. a solid structure for the base,

2.warm and predictable water temperatures and oceanic salinities,

3. clear, transparent waters low in phosphate and nitrogen nutrients,

4.and moderate wave action to disperse wastes and bring oxygen and plankton to the reef.

Corals live in all oceans of the world from the Arctic and Antarctic to the tropics. The largest reefs occur in the warmer portions of the Pacific and Indian oceans however they are also found in the Caribbean and gulf of Mexico and southern Florida.

Numerous species occur in the different areas ranging from 40 or more in the West Indies to 200 or more on the Great Barrier Reef (because of their great skeletons, their fossils have yielded more than 6000 extinct species.) Corals can live in water below 68-70 degrees (reef min. temps) but don't form reefs, just like some corals which can live 19,000 feet below the surface, but reef building corals are in water usually less than 300'.

There are three types of reefs, 1. fringing, which follow the coastline and form along the coast, 2. barrier reefs, which lie parallel to the coast and separated by a narrow lagoon, and 3. atolls, which are associated with rims of extinct volcanoes which sunk back into the ocean leaving a circular rim of coral around a deep lagoon.

Great care must be taken to minimumize human damage and though the reefs are well marked on the charts, every year careless boaters run aground destroying coral colonies hundreds of years old. From the surface reefs have a unique golden brown color. If you see brown, you may be about to run aground. Anchors, hooks traps and touching all injure or damage or destroy corals by leaving it vulnerable to infection by microscopic organisms that can kill the animals.

The Animal

The adult coral, stationary at this stage in life is called a polyp which can reproduce in two different ways. One is by means of eggs that, when fertilized by sperm, develop into tiny swimming larval organisms called planulae. They eventually settle down on the bottom of the ocean, on a rock etc. and develop into polyps. Each polyp builds a limestone skeleton attached to the surface on which the polyp has landed. After establishment, the upper part of the polyp becomes domed shaped, develops a body and a mouth with tentacles around the mouth used to draw in food from the surrounding waters. The tentacles are armed with specialized stinging cells called nematocysts that paralyze tiny prey. (mostly at night)

Another process is by budding which offshoots called buds grow out from the body and remain attached sending out more buds. Some corals, the buds break off to become separate individuals. The largest solitary polyps grow to a diameter of 10 inches (25cm) while polyps of colonial species form from .04-1.2inches in diameter.

(comptons CD Rom1990)

The coral reef has a very high order of internal organization, greater even than the tropical rain forests they are often compared to. Both receive high levels of solar radiation, the ultimate source of all ecosystem energy. (p63 Great Barrier Reef).

CORAL BIOLOGY 63 coral taxa in keys

2 CLASSES of reef corals exist, HYDROZOA AND ANTHOZOA. In the keys, Millepora (fire coral) is the only hydrozoan coral on shallow reefs. Stylaster and Distichophora are found in deep habitats. The anthozoans include octocorals, zoanthids, stony corals, false corals, and anemones. Reef corals are colonial, often containing thousands of individual members or polyps.

---------Fire Coral-(M. complanata)--------------------Fan Coral....Keys

 

FIRECORAL...MILLEPORINA The stinging/burning comes from nematocysts. 2 species of firecoral are found in Florida reef. The bladed is a keel shaped (M. complanata) restricted to shallow windward reef tops. Crenulated (M. alcicornis) is a branching species found in a much wider range of reef habitats. Fire corals are successful in colonizing living octocoral branches.

 

In 1842, Charles Darwin devised a scheme to describe coral reefs that still dominates their classification. He described them as "fringing reefs" attached to the mainland or island, "barrier reefs", and open ocean atolls. Fringing reefs, the simplest reef landforms, are built upwards and outwards in shallow seas adjacent to islands or continents. Barrier reefs occur further offshore, separated from the mainland shore by a shallow lagoon. In contrast, atolls are found in the deeper oceans, having usually developed over volcanic foundations that have subsided beneath the sea. Coral growth in this case produce saucer like reefs with central lagoons.

 

Coral reefs can only grow up to about the level of a low spring tide, and reefs (as opposed to individual corals) will probably not develop in water more than 40m deep. Reefs are, therefore, strongly influenced by sea level. Over the time that most of the world's reefs have grown, there have been major sea level changes. There were two main reasons for sea level changes. One, the worlds ocean basins have changed in size and shape because of sea floor spreading and plate tectonics and the other is the ice ages.

 

ZONES OF THE MODERN REEF.

In the last 8000 years, reefs have grown to what they are today. They have grown from the older reef platforms about 15-20m deep. The modern reefs are relatively thin and their shape reflects accurately the shape of the surface over which they are growing.

To understand the growth of modern reefs, its best to begin at the surface, where five easily defined zones can be identified:

1. the reef front,

2. the reef crest,

3. the coral flat,

4. the sand flat, and

5. the lagoon.

The upper slope of the modern reef front extends from the mean low-water level of spring tides down to a depth of 10 to 20m. Fairly steep, sometimes vertical, sometimes terraced, and often serrated by coral covered spurs and channels, the area has a lot of coral cover. On some reefs, the front is protected by a line of patch reefs, many of which are joined to form an outer front.

The exposed windward reef crest, or outer reef flat, lies above the mean low-water level of spring tides. It is composed of either a seaweed, stepped surface of encrusted coralline algae and devoid of corals, or a flat coralline-encrusted surface that may reach half a meter above the mean low-water level of spring tides, as on a ribbon reef. The upper surface of the reef crest is sometimes covered by a green turf of fleshy algae, which provide a home for countless small organisms, particularly foraminifera. These algae pavements can reach 200-300m wide and form in response to the high energy conditions typical of windward edges. These algal pavements are replaced by extensive coral development in lower energy or more leeward parts of the edge of the reef.

The coral flat or reef flat, occurs on the sheltered or lee side of the algal flat. It usually consists of an aligned coral zone where most corals are encrusted by coralline algae. These aligned corals occur in patches 1 to 2 m wide and 20m long formed by coral growing parallel to the direction of waves refracted across the top of the reef. The water movement is channeled across the grooves between the aligned assemblages of coral and in this way, coral growth on the reef top controls the backward flow of water across the reef. Nutrients and sediments are carried back through these channels to the sand flat and lagoon areas. This zone is usually separated from the lagoon by a sand flat, sometimes up to 500m wide. The sand flat is made up of broken skeletons of corals, coralline algae, and other reef organisms derived from the reef front and coral flat and transported toward the lagoon as sands and gravels. Foraminifer from the algal turf of the reef crest also form part of this sediment.

Sand flats have been built by prevailing swell and waves that continually destroy the reef front and transport the broken products backwards. The surface of the sand flat, covered by one half to two meters of water, depending upon the tides, is often sparsely covered by small colonies of branching corals which can grow from fragments brought from the coral flat which grow when they come to rest. What can happen is that as these pieces start to grow a small solid patch eventually forms after larva of massive corals settle and grow. In this way, the coral flat extends backward across the sand flat, and the sand flat will migrate into the lagoon.

The lagoon is best seen in platform reefs, where they reach 5-10m deep with the deepest part on the leeward side of the reef. Lagoons are sometimes open with very few patch reefs rising from the floor or often very crowded with patch reefs making navigation of the lagoon difficult.. These patch reefs whether they form discrete circular or network-like structures, usually rise vertically from the lagoon floor. They are made up of many species of branching and massive corals, the dead parts of which are encrusted by coralline algae. The lagoon floor consists of coral sand, which becomes finer away from the windward margin and patches of mud (very fine) sometimes occur in the quiet waters of the leeward margins. Because the lagoons are depositories for sediments and organic material created on the windward margin, they are slowly filling up.

 

About 6000 yrs ago, sea level established and maintained a position close to what it is today. In ten meters of water, corals grow upwards toward the light, so that the reef surface grows upward from the deeper, quiet water to the high energy surface environment characterized by heavy pounding of the surf. The types of corals that make up the reef change as the environment changes.

The composition of the reef also varies with the position of the reef on the continental shelf. The structure of the outer shelf-reefs generally reflects the influence of powerful waves, and here most of the reef consists of coral skeletons forming a porous, but relatively stable framework. Reefs in the middle and inner parts are dominated by accumulations of sand, and the coral framework forms a much smaller proportion of the reef, reflecting the calmer sea, or lower energy conditions compared with the outer reef.

 

3 stages of reef development can be seen.

1. vertical growth to sea level...a reef growing slowly from a deep substrate may not yet have reached sea level or only recently have reached sea level and is characterized by vigorous growth of free-standing branching or massive corals upwards to sea level. Such a reef is termed juvenile.

A reef growing from relatively shallow substrate, or one growing rapidly from a deeper substrate, will reach sea level quickly and will be subject to the influences of shallow water for a long time...many have been at sea level for 4 to 6000years. Swell, waves and currents help develop these and these reefs are called mature.

Reefs growing from very shallow substrates, or small reefs that have grown rapidly from deeper substrates, may have been at sea level even longer than mature reefs and because a long time at the surface leads to destruction of the reef, lagoons will have been filled in and the typical zonation destroyed. Erosion is thought to exceed production, and such reefs are called senile.

Its believed that reefs progress through the growth stages from juvenile to mature to senile. Different reefs require different lengths of time to follow this progression, the time being dependant on depth and size of substrate, rates of growth, length of time at sea level, and intensity of the processes operating at sea level. As reef growth has seldom lasted for more than 5000-15000 years, some large lagoon reefs may not have sufficient time to progress through the complete cycle in one high-sea-level growth phase and could need more than one growth phase to reach a senile condition.

Maintenance and Destruction

Reefs come in a vast array of shapes and sizes and many of these differences result from erosion while periodically exposed during low-sea-levels rather than from growth differences. While the reefs are biologically complex with the many plants and animals, they are also ecologically organized with a series of zones across the reef, each serving a specific role in providing food, consuming wastes, recycling nutrients, and creating and maintaining the limestone structure that is the reef.

The clear boundaries and isolation make coral reefs excellent examples of the natural order of things.

Many of the worlds tropical oceans have few plant nutrients, which result in little plankton growth (the absence which results in the beautiful blue color usually associated with tropical seas), but coral reefs show no particular preference for the most barren areas of the ocean and can live in water very low in plant nutrients and plankton to water that is quite enriched. The enriched environments often find the reef not being able to compete with other marine systems dense beds of large algae populated by filter feeding animals such as barnacles. Though reefs don't prefer to struggle for nutrition, they have developed the ability to thrive in barren areas of the ocean more effectively than other marine systems by creating and recycling their own internal food supply.

Chemical runoffs can either be destructive such as herbicides and insecticides or enriching, such as fertilizers. In either case the viability of a coral reef community is threatened. Inshore reefs whether they be stable or in decline, do not develop the structured zonation and balanced communities of the outer reefs because they exist in enriched and biologically active waters and internal recycling of the food supply in not essential.

Needs

A coral reef requires only the basic plant nutrients plus a copious supply of calcium for the construction of the calcium carbonate of the coral skeletons and other limestone forming materials of the reef. Carbon dioxide and calcium are abundant in sea water. N, P and some trace elements may only be present in limited quantities in the clear oceanic waters and the reef must recycle these materials to maintain its intense biological activity. All plant and animal matter grown must be totally consumed or fully degraded within the reef community to prevent the loss of any nutrients. Extensive mats of blue-green algae on the reef may provide the reef with N by converting the N in the atmosphere to the soluble inorganic N nutrients.

There are very small but important losses and gains from any reef system and that is the exchange of larval forms with other reefs. This ensures inbreeding and that any species depleted by disease or other stress will be replaced by larval input from another reef or reefs.

About 3/4 of the CO2 that is removed from sea water by a coral reef in each 24hr period is used directly in photosynthesis within the reef algae. This creates about 20g of new organic matter for every square meter of shallow, reef-flat environment per day and can be up to 50g a day in areas of intense biological activity. This is the reefs food supply.

Most of the limestone making up the solid underlying mass of the coral reef consists of skeletons of once living corals. This material may remain where it grows, though it is perhaps more commonly broken off and redeposited in other parts of the reef. One thing certain, corals cannot cement their skeletons together in a solid reef structure, they mearly form a vast quantity of limestone. They provide the aggregate of the reef concrete. At least some of the corals in this rich surface growth are likely top add to the structural framework of their own reef when they die.

The encrusting coralline algae hold together the sand and framework materials of the reef to create a solid surface. They have a role in building a real reef rather than a pile of uncemented coral debris and sand. Once the reef has been totally consolidated by these algae, chemical precipitation of more carbonates in the reef structure provides additional cementing of the remaining loose calcium carbonate materials. Its a slow process but it makes the entire structure more rigid. The final reef material is a porous but strong limestone, though it frequently contains uncemented regions.

NUTRIENTS AND REEF PRODUCTIVITY

Direct feeding by the polyps usually only supplies only 10 per cent of the corals energy needs. In such cases, most energy comes from photosynthesis by zooxanthellae, which obtain nutrients from metabolic waste products of the coral host as well as from the seawater or detritus. Coral reef primary productivity is usually very much higher than areas where these nutrients are more abundant but recycling rates of the corals and zooxanthellae are high but the harvestable primary productivity is low because most of the organic matter produced is metabolized and nutrients are freed to be reused in photosynthesis.

 

Almost every gram of organic matter created by a coral reef is consumed and eventually finds its way back to the sea water as carbon dioxide. Before most of the organic matter is finally degraded back to CO2, it may move through all or part of the complex and finely balanced coral reef food web.

What is the result of a reef creating and totally consuming so much food material? First, it allows the continuing maintenance by reproduction of the coral reef community by feeding the sun's energy into the system. Second, and perhaps most significantly, it provides the energy needed to remove the other quarter of the total of CO2 used by the reef in a 24-hour period. This additional CO2 is used in the biological formation of calcium carbonate or limestone. The limestone created us mostly retained by the system, giving rise to the physical growth of the reef structure.

Reefs may be thought of as assemblages of beautiful animals but in fact they are dominated by the activities of plants. The whole system is driven by the photosynthetic activities of plants, just like most ecosystems existing in light. Even the corals function principally as plants, deriving as much as 90% of their total and energy requirements from the tiny algae, known as ZOOXANTHELLAE, contained within their coral tissues. The remaining requirements are met through feeding on reef plankton.

Apart from the corals, the major plants providing the food supply of the reef are fine filamentous algae that form a rapid growing fuzz or turf over almost all available surfaces within the reef. This turf is grazed by animals, which in turn are preyed on by larger animals and so the food web expands. Also, all living materials die and undergo microbial decay, forming the basis of yet another component of the complex food web. The reef also creates and consumes its own plankton. Each animal and plant serve a vital role in the reef's finely tuned balance.

The Factory

The 10 to 30 grams of calcium carbonate or limestone created everyday for each square meter of the active parts of the reef are retained somewhere within the general reef environment. The reef thus exhibits real, measurable growth over hundreds of years. The energy to enable the creation of all this limestone comes into the system through algal photosynthesis. Much of the limestone originates as growing coral but other organisms, such as many algae, tiny single celled forams, and shells make major contributions. The cements in the limestone rock are partially deposited by algae and partially chemical precipitation.

Photosynthesis by zooxanthellae also promotes production of skeletal limestone's that make up the reef framework. Zooxanthellae provide coral with the energy needed to calcify. (They also prevent phosphate poisoning of calcification by removing phosphatic wastes and any phosphates from the microenvironment (phosphate inhibits the precipitation of aragonite crystals, the skeletal building blocks of corals))

Photosynthesis uses CO2 and water from respiration raising the pH of the system end enhancing aragonite precipitation.

During calcification, calcium ions, which are abundant in sea water, combine with bicarbonate ions, also found in the environment and the following reaction occurs...

 

1 Ca2 + 2HCO3 -----> Ca(HCO3)2 and then calcium carbonate and carbonic acid are produced...

2 Ca(HCO3)2----->CaCO3 + H2CO3

but carbonic acid can't exist so carbonic acid must be ionized

3 H2CO3---> H+ + HCO3- or converted to water and CO2

4 H2CO3----> H2) + CO2

 

Reactions 3 and 4 are catalyzed by the enzyme carbonic anhydrase, which is found in the calicoblastic epithelium the corals tissue layer where calcium metabolism is most active. Calcium Carbonate is apparently stored then actively transported in a system of microvessels to the deposition sites where it is deposited as aragonite crystals. It has also been suggested that the zooxanthellae provide glycolate, which is converted to glyoxylate and combined with urea to form allantoic acid. This may be the medium by which calcium and CO2 are transported to sites of calcification.

Destruction

One of the obvious of all reef destroying processes are storms. But not all reef destruction is caused by physical forces. Many animals and even some algae live out their lives inside the reef structure and even in the skeletons of still-living corals and other organisms with hard skeletons. Some of these graze off of the reef surfaces and remove considerable amounts of the limestone at the same time. These boring and grazing organisms weaken the structure of their host or the reef itself by physically disrupting the limestone materials. This in turn, forms more fine sand and calcium carbonate detritus in the reef system. But the boring organisms also dissolve, using acid secretions, much of the calcium carbonate they remove (about 5-25% of total CaCO3 deposited by the reef)..

 

Readers digest Great Barrier Reef pp64-86.

 

 

 

CORALS EXTRA

BIOLOGICAL INTERACTIONS

 

Of course, grazing and predation can be readily observed but on coral reefs, disease, competition, chemical warfare, bioerosion and symbioses are also common.

Pathogens may injure and kill corals, and black band, one such pathogen usually attaches to a coral following tissue damage.

Competition include overgrowth denying light and water movement.

Allelopathy (chemical defense and offense) is also used to prevent overgrowth and gain living space.

Damselfish destroy coral tissue and farm/defend algae on the dead coral.

The black sea urchin crops algae from the reef and this provides settlement habitat for coral larvae.

Sponges bore into coral skeletons, weakening them, some bind to them and some protect the undersurface from attacks by boring organisms.

 

 

Chapter Questions

Coral Reading with Questions

1  State Of Coral Reefs in ..by Carlos Goenaga                    

1.How old is the recent Caribbean Coral Reef System?

2  List 5 socioeconomic importance’s of coral reefs and give an example of each.

3.  How are reefs a buffer for the CO2 cycle?

4.  What 3 human activities threaten Caribbean reefs?  How do they occur?

5  How does upland clearing effect coral reef?

6  How does sewage discharge effect coral reefs?

7. The discovery of what about coral has made the destruction of reefs an international interest?

 

 

Coral Readings

 

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Marine Ecology

Lecture Notes -

Marine ecology is the branch of ecology dealing with the interdependence of all organisms living in the ocean, in shallow coastal waters, and on the seashore. The marine environment for all organisms consists of non-living, abiotic factors and living, biotic factors.

Abiotic The abiotic factors include all the physical, chemical and geological variables that have a bearing on the type of life that can exist in an area. Included are

• water
• light
• temperature
• pH
• salinity
• substratum
• nutrient supply
• dissolved gases
• pressure
• tides
• currents
• waves
• exposure to air.

Biotic The biotic factors are the interactions among living organisms. Zonation Two major divisions in the marine world.

• Pelagic zone...waters of the world and benthic zone..the ocean bottom.

The pelagic zone include the productive coastal waters..neritic zone and deep waters of the open ocean..oceanic zone. Another division in the pelagic zone is related to light penetration..the photic and aphotic zones.

The benthic zone extends from the seashore to the deepest parts of the sea. The material that makes up the bottom is the substratum and the organisms living there are the benthos.

Tides uncover parts of this zone and the area uncovered is the intertidal zone, above is the supratidal zone, affected by salt spray but not covered by sea water and below the intertidal zone is the subtidal zone..submerged and extending seaward. The elevation and slope determines the length of time its exposed. This affects organisms living there because some are restricted to zones according to their adaptations to this type of zone (intertidal etc.).

Organisms living in pelagic waters also put up with changes in salinity, temperature etc. and inhabit the coastal areas etc. which fit their adaptations. (can withstand large changes (eury-- prefix) and narrow tolerance (steno))

Other zones include the surface waters of the coastal areas called the neritic zone and the waters of the ocean called the epipelagic zone.The open ocean is less productive than the neritic zone which contains plant plankton, fish larva, invertebrate larva that will eventually end up near the coast.

The open ocean is divided into zones depending on the amount of light it receives...from the epipelagic layer to the mesopelagic zone 200-1000m in which daytime inhabitants migrate upwards during the night, bringing back nutrients and some exhibit bioluminescence (light producing organs called photophores). The deep sea layers bathypelagic 1000-4000m and the abyssopelagic zone (below 4000m) have limited food supplies although bacteria have been found that can make their own food.

TROPHIC (FEEDING) RELATIONSHIPS Energy transfer is accomplished in a series of steps by groups of organisms known as autotrophs, heterotrophs, and decomposers. Each level on the pyramid represents a trophic level.

Autotrophs absorb sunlight energy and transfer inorganic mineral nutrients into organic molecules. The autotrophs of the marine environment include algae and flowering plants and in the deep sea are chemosynthetic bacteria that harness inorganic chemical energy to build organic matter...AUTOTROPHIC NUTRITION..supply food molecules to organisms that can't absorb sunlight.

HETEROTROPHS Consumers that must rely on primary producers as a source of energy...heterotrophic nutrition. The energy stored in the organic molecules is passed to consumers in a series of steps of eating and being eaten and is known as a food chain. Each step represents a trophic level and the complex food chains within a community interconnect and is known as a food web.

DECOMPOSERS The final trophic level that connects consumer to producer is that of the decomposers. They live on dead plant and animal material and the waste products excreted by living things. The nutritional activity of these replenish nutrients that are essential ingredients for primary production. The dead and partially decayed plant and animal tissue and organic wastes from the food chain are DETRITUS. This contains an enormous amount of energy and nutrients. Many filter/deposit feeding animals use detritus as food. Saprophytes decompose detritus completing the cycle.

ENERGY TRANSFERS IN MARINE ENVIRONMENTS Primary producers usually outnumber consumers and at each succeeding step of the food chain the numbers decrease. The numerical relationship is called the pyramid of numbers. (base as opposed to each step.) The energy pyramid is the energy distribution at each trophic level as it passes from producers through the consumers. Some energy is lost as it passes to the next level because

• (a) consumers don't usually consume the entire organism
• (b) energy is used to capture food
• (c) organisms used energy during their metabolism
• (d) energy is lost as heat.

Generally only 10% will pass on to the next level. (The shorter the better..)

FOOD RELATIONSHIPS Predator-prey..predator kills and eats another organism... the prey. Antipredator defenses have evolved LIKE

• POISONOUS SECRETIONS,
• SHARP SPINES AND THORNS
• THE HARD SHELL-LIKE CONSTRUCTION of Coralline algae also deters grazing sea urchins

.

Scavengers..feed on dead plants and animals that they have NOT killed...crabs ripping chunks of flesh from fish on the beach are scavengers. Most scavengers consume detritus rather than flesh and deep sea animals can feed on both.

Symbiotic...refers to close nutritional relationship between two different species...

• commensalism- one benefits
• mutualism both benefit and parasitism
• one benefits at hosts expense.

Population Cycles ..density or numbers of individuals depends on

• 1. natality or rate of production of new organisms and
• 2. mortality..rate of death in a population.

Now to be stable the two must be in equilibrium but under favorable conditions, populations can increase numbers (can be seasonal and geographical) but this also increases mortality because of decreased food supply and living space and increased predation. If mortality is greater, then the population decreases. These favorable conditions depend on

• high concentration of nutrient rich water,
• rapid cycling of materials by decomposers,
• high numbers or rapid turnover of producer organisms
• Light
• nutrients including nitrate, phosphate, silicon, potassium, magnesium, copper, iron.

Silicon dioxide needed for outer glass covering of diatoms and forms internal structural parts of sponges, K and NO4 and PO4 needed in plant proteins, lipids and carbohydrates during photosynthesis. and the nutrients can be considered a limiting factor as well as pH temp. light , depth salinity nesting sites and predation.

Distribution Pelagic world include the drifting organisms...plankton and the swimmers...nekton.

Plankton comprise the large and small organisms that drift or float while tides and currents move them through the water. Most plankton do have a limited ability to move and can migrate vertically through the water from day to night. Some drifters can photosynthesize while others are consumers.. Plankton is very important as it occupies the first two or three links in the marine food chains.

Nekton use fins, jets of water, strong flippers, flukes and flippers to swim through the water.

Benthic If the organism resides primarily in or on the substrate and doesn't swim or drift for extended periods as an adult it is considered benthic. They either burrow , crawl, walk, (motile) or are sessile..permanatly affixed to the substrate or each other. Demersal organisms, such as flounder alternate between swimming and resting on the bottom. Living on the bottom are epifauna and living within are infauna. The substrate could be a source of food.

PLANKTON Phytoplankton, plant plankton,are the important primary food producers in the pelagic environment. The animal members of the plankton are the zooplankton which range from bacteria size to 15m jellyfish. Phytoplankton are the trees of the sea which float near the surface to make the most of the sunlight for photosynthesis.Two forms of phytoplankton, dinoflagellates and diatoms are particularly important as founders in the planktonic food webs because most of the animal life in the oceans depend on these. The dinoflagellates are usually found in warmer waters, and the diatoms are usually more abundant in cooler waters. Other plankton, coccolithophores and silicoflagellates are also abundant as well as blue-green algae (in certain locations it can become the dominant) and green algae but usually in the coastal water (some are in the open ocean as findings of chlorophyll b indicate. Phytoplankton have adaptations which deal with methods of keeping them in the upper zones to stay in the sunlight.. Size...small sizes retards sinking, structure...shape/structure of the diatoms effects sinking rate and density...decrease by storing droplets of oil in the cytoplasm. Blooms Although unknown, the availability of nutrients, amount of vertical mixing, salinity, density, temperature, and depth of water affect phytoplankton growth rates. Blooms called red tides have occurred in almost all oceans. Red tides usually refer to the discoloration of the waters as a result of the absorption of light by pigmentation in planktonic organisms. The red water usually results from actions of non-toxic organisms and the term red tide is inadequate when used with reference to PSP (paralytic shellfish poisoning) and toxic dinoflagellates will not always discolor the water (too few) but may be numerous enough to toxify shellfish. Some mysteries have been solved but evidence that PSP may be increasing in intensity and spreading to new areas is surfacing. About 60 species of dinoflagellates may color offshore waters however only 6 have been shown to produce toxic substances. Some toxins, saxitoxin, is 50x more poisonous than curare (used by SA Indians). Repeated cell divisions as result of long period of dry weather following a violent storm which stirs up bottom sediments, reach concentrations of 25,000 dinoflagellates /ml of water. Bioluminescent phytoplankton bloom in the ocean and produce a bluish-green light. Phosphorescent Bay in Puerto Rico contains high concentrations of bioluminescent phytoplankton throughout the year. One type, Noctiluca sp. Disturbing water, passing of boat, wave breaking, initiates bioluminescence. Zooplankton..500,000 per gal and range in size from single cell to jellyfish. Almost any animal phylum can be found wandering through the sea but the most common are Copepods (95%). Two types of zooplankton....Holoplankton or permanent members of the community and temporary residents called Meroplankton. Holoplankton have evolved efficient means of remaining adrift...special appendages, droplets of oil and wax, tread water, jelly-like layer, gas-filled float. A majority of inverts and many verts. have planktonic stages (meroplankton) Drifting eggs and larva of fish, crabs, barnacles, worms, clams, snails, sponges, lobsters, etc. They use the water mass to feed and disperse their planktonic young to new habitats. The reproductive cycles often coincide with maximum concentrations of food and favorable currents. EX. polar oceans, spring phyto. bloom triggers increases in zooplankton coinciding with migration patterns of whales, seals and penguins. Vertical migrations refers to Copepods and other zooplankton moving up toward the surface to feed in the evening responding to the changing light reducing predation during the day because they are in deeper layers. This varies among species but light, shadows and pigments of phytoplankton (color) helps zooplankton locate food. Thus buoyancy, mobility, vertical migration, and chemical sensing enables Copepods to search open water for concentrations of food. Trophic levels in zooplankton communities Energy incorporated in organic molecules by marine plants flows to the zooplankton community in a complex series of interconnected food chains. Each chain or part of the web serves to link phytoplankton to larger pelagic animals through the zooplankton. Herb. zoo eat phytoplankton while carniv. zoo occupy the third level as secondary consumers. Nekton Free swimming organisms equipped to direct their movements through the sea including cephalopods, fishes, marine mammals, sea turtles and marine birds. Many are at the top of the trophic levels either as carnivores or herbivores without natural predators..except man. Swimming allows escape or movement toward food and methods of locomotion are very diverse, from jets of water, flippers, large tail fins and flukes. Planktivorous nekton are animals that feed directly on plankton such as baleen whales and some fish. Herbivorous Nekton are ones that feed on large seaweeds ad sea grasses (turtles and manatees) Carnivorous Nekton are the dominant carnivorous animals of the pelagic environment and generally these animals migrate great distances in search of food. Production Food production occurs mainly through Photosynthesis. It is measured and called Primary food production which will occur in the photic zone as phytoplankton manufacture organic matter during photo. The primary productivity varies seasonally and geographically. It is measured as g of Carbon/m2/year. (Long Island Sound 500g, Antarctica. 2-400g etc.) . It seems that the more vertical mixing that occurs in an area, the higher the primary production is because in the tropics where there is little vertical mixing, their Primary Productivity is low because of the depletion of nutrients in the surface waters. Primary productivity decreases as depth increases as there is less light and less photo. Accessory pigments in algae enable them to make the most of the little light that does get to them. The boundary where the food production (photo) is balanced out by the rate of respiration (the use of the food) is called the compensation depth. Copepods metabolize droplets of diatom oil to liquid waxes and fats which can be used as long-term energy reserves. (waxes; long/fats short). It is these waxes and oils that get used for blubber when the Copepods/krill are fed on by marine birds and mammals. Detritus food chains are also secondary when decaying material enter the detritus chain as decaying materials, wastes, pieces of animal tissue. The swarms of Copepods feeding on diatoms excrete packets of partially digested matter called fecal pellets. These pellets usually aren't eaten by other pelagic organisms and provide food for bacteria when they settle as well as a host of detritus feeders on the bottom (transfer of energy from the top to the bottom). While there is a loss of energy to the grazers, many consumers are adapted to feed on detritus thereby returning energy to the food chains. Chitionolytic bacteria can break down chitin which represents an enormous source of organic carbon. Some are even symbiotic and found in the intestines of certain pelagic organisms to help them digest chitin. These bacteria play a big role in making sure the billions of tons of chitin produced in the marine environment each year get broken down and their nutrients are returned to the primary food makers.
 

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·       
Scientific
Classification

Systems

 

·        Why a Scientific Classification System?

·        Ambiguity of terms

·        Latin “dead language”

·        Categorization of relationships:

·        Evolutionary

·        Structural

·        Biochemical

·        (NOT habitat)

·        7 Classification Groups:

·        Kingdom (most inclusive)

·        Phylum

·        Class

·        Order

·        Family

·        Genus

·        Species (most specific)

·        King

·        Phillip

·        Came

·        Over

·        From

·        Greece

·        Singing

·        5 Major Kingdoms:

·        Monera

·        Protista

·        Fungi

·        Planta

·        Animalia

·        1 cell, prokaryotes

·        1 cell, eukaryotes & algae

·        Multicelled, absorptive feeders

·        Multicelled,  autotrophs

·        Multicelled heterotrophs

·        Cellular Tree of Life

·        Which is the most difficult to assign?

·        Species:

·        Most specific

·        Successful interbreeding

·        Fertile offspring

·        Which group has the largest # organisms?

·        Kingdom:

·        Cell types

·         Prokaryotes

·        Eukaryotes

·        Cell number

·        Nutrition

·        Structures

·        Plant Kingdom* 
*Division replaced by Phylum

·        PLANT SYSTEMATICS

·        Common names

·        Have evolved over centuries in a multitude of languages

·        Sometimes used only in  a limited geographical area

·        Problem with common names:

·        One plant may be known by several names in different regions, and the same name may be used for several different plants…

·        Phycology by fiat

·        The blue-greens are not algae any more ... any more.

·        It seems that they’re not lost, but gone before.

·        By a stern decree despotic,

·        Since they’re all prokaryotic,

·        The poor blue-greens can’t be algae any more.

·        Euglena’s not an alga any more ... any more, are not algae anymore.

·        Whatever people thought of it before.

·        Its form is somewhat plastic

·        And its pellicle’s elastic,

·        So Euglena’s not an alga any more.

·        Spirogyra’s not an alga any more ... any more,

·        Though it passes nuclei from pore to pore,

·        Since it hasn’t swimming gametes

·        It’s reclassified with Trametes.

·        Spirogyra’s not an alga any more. ore.

·        Red algae are not algae any more ... any more,

·        Though the reddest weeds abound on every shore.

·        Since their microsporulation

·        Is devoid of flagellation,

·        The red algae can’t be algae any more.

·        You cannot regard an alga as a plant ... as a plant.

·        However much you want to, you just can’t.

·        If it’s not to late to switch

·        You should throw away your Fritsch,

·        For the algae are not algae anymore.

·        Scientific names

·        Similar plant species form a group called a genus (plural: genera)…

·        Genera are grouped into families…

·        Families into orders, classes, divisions and kingdoms

·        Kingdom-Division (Phylum)-Class-Order-Family-Genus-Species

·        “King David Came Over For Great Spaghetti”

·        “King David Conquered Our Fifty Great States”

·        Species name

·        Each species has a single correct scientific name in Latin called a binomial (two names) – it is always italicized or underlined.

·        First name is genus name.

·        Second name is species name

·        Human:  Homo sapiens              

·        Cat:     Felis catus                    

·        Dog:    Canis familiaris               Wolf: Canis lupus

·        Through the lens of a high-powered microscope, Karen Steidinger of the Florida Fish and Wildlife Conservation Commission stares down at her nemesis of the past 43 years. Karenia brevis, as a Danish colleague renamed this plantlike speck of algae in tribute to Steidinger’s groundbreaking contributions toward unraveling the mysteries of it cloverleafshaped body, twin tails and – under normal circumstances –laid-back lifestyle in the warm Gulf waters off western Florida.

·        Examples

·        Genus of maple trees is Acer

·        It has many species including:

·        Common name                    Scientific name

·        “Red maple”                       Acer rubrum

·        “Sugar maple”                   Acer saccharum

·        “Black maple”                    Acer nigrum

·        Taxonomic hierarchy

·        Species that have many characteristics in common are grouped into a genus.

·        Related genera that share combinations of traits are grouped into families.

·        Families are grouped into orders.

·        Orders into classes

·        Classes into Phyla

·        Related phyla are grouped into kingdoms

·        (e.g. house, street, city, county, state, country, continent, planet)

·        What is a species?

·        Species: a set of individuals that are closely related by descent from a common ancestor and ordinarily can reproduce with each other, but not with members of any other species.

·        Biological species: group of interbreeding populations. Offspring are fertile.

·        Pleonosporium flexuosum (C.Agardh) Bornet ex De Toni

·        Plocamium coccineum var. flexuosum Hooker & Harvey  

·        Plocamium flexuosum (Hooker & Harvey) Harvey

·        Plocamium leptophyllum var. flexuosum J.Agardh  

·        Pseudophormidium flexuosum (Gardner) Anagnostidis & Komárek

·        Sargassum oligocystum var. subflexuosum Grunow

·        Schizonema flexuosum (Cleve) Kuntze

·        Pinnularia flexuosa Cleve  

·        Scytonema flexuosum Meneghini

·        Stigonema flexuosum W.West & G.S.West

·        Triceratium flexuosum Greville - Unchecked

·        Species

·        Some members of same species look very different…

·        Definition of species

·        Or, plants look the same, but due to  polyploidy
(more than the diploid number of chromosomes), they cannot interbreed.

·        For example: Ferns;  evening primrose

·        Carolus Linnaeus

·        Swedish scientist – Carl von Linne

o   (doctor and botanist)

o   born in 1707.

·        Called the “Father of Systematic Botany”

·        Established modern system of nomenclature

·        Linnaeus legacy

·        His binomial system of nomenclature, in which the genus and species names are used.

·        He classified 12,000 plants and animals, and many of the names he first proposed are still in use today…

·        Hypoglossum subslmplex Wynne sp. nov.

·        Fasciculus lamina rum simplicium aut subsimplicium erectarum delicatarum e base disciformi orientium; ranNflcatio tantum ad unum ordinem; laminae tantum usque 6 mm altae; margins laminae laeves; costa corticata destituta; omnes cellulae serierum cellularum secundi ordinis series cellularum tertii ordinis procreant; tetrasporangia tantum in una lamina procreant, cellulis ambo serierum secundi ordinis et tertii ordinis abscissa, vicina costa laminae, sic laterales cellulas pericentrales includentibus; sorus tetrasporangiorum non discretus in longitudino sed ad aliquot distanciam currens; sori spermatangiorum plerumque in turmis diagonaliter aut irregulariter dispositi, parvi et sejuneti aut confluentes; uno aut duo cystocarpiae in quoque femina lamina, in costa locatae.

·        Diagnosis: A cluster of simple or subsimple erect, delicate blades arising from a discoid base; branching to one order only; blades only up to 6 mm tall; margins of blade smooth; corticated midrib lacking; all second-order row cells producing third­order rows; tetrasporangia produced in only the primary layer, cut off by cells of both second- and third-order rows in vicinity of midline of blade, thus including lateral pericentral cells; tetrasporangial sorus not discrete in length but running continuously for some distance; spermatangial sori arranged usually in diagonal or irregular groups, small and isolated or becoming confluent; I or 2 cystocarps per female blade, located on the midline.

·        Holotype: Wynne 9959 (slide in MICH), on Halimeda tuna, collected by M. D. Hanisak, 19 June 1994, Content Keys, lee side of Florida Keys, Florida, U.S.A. Isotypes: slides deposited in MEL, PC, UC, US.

·        Animal Kingdom

·        Scientific Name:

·        Latin

·        Italics or underlined

·        Genus species

·        Homo sapien

·

·        Bacteria and Archaea constitute two of the three known taxa placed at the level of Domain, the most inclusive of all catagories.  All other names and taxa in the figure are in the third domain: Eukarya

·        Excavata

·        the single characteristic that unites them is the presence of certain sequences of DNA not seen in other groups. The name is derived from a feeding groove present on one side of the cell in some species, but not common to all members of this group.

·        Chromalveolata

·        This is an extremely diverse group, Based upon molecular and cellular data, species share a common plastid origin and pigment structure, and cellulose cell walls.

·        Alveolates

·        A common feature of this clade is the presence of membrane-enclosed spaces beneath the cell membrane called alveoli.

·        •       Haptophytes

·        Members of this clade have a haptonema, a unique cellular structure resembling a flagellum, but differing in both structure and function.

·        Stramenopiles

·        A common feature of this clade is the presence of tubular hair-like structures covering one of their two flagella (called a "tinsel flagellum").

·        Rhizaria

·        . Although diverse, many species (not all) have thread-like cytoplasmic extensions. This grouping is controversial.

·        Include Forams (Foraminiferians) and Radiolarians

·        Archaeplastida

·        Based upon comparative molecular and cellular structural data, members of this group share a common ancestor.

·        Red algae form a monophyletic clade. Most are multicellular and marine. They have chlorophyll a, but also have large amounts of the pigments phycocyanin and phycoerythrin, which give them their distinctive red, brown, and purple colors. No flagellated cells have been found in red algae. Life cycles in some are very complex.

·        •       Green Algae This name refers to the bright green color of a pigment within the photosynthetic structure called a chloroplast. The pigment is common to these organisms.

·        True plants are paraphyletic with the green and red algae. They are multicellular and have chlorophyll a. All exhibit life cycles with alternation of generations where the fertilized egg develops into a multicellular embryo within protective cells on the female plant.

·        Unikonta

·        Molecular data support the hypothesis that this diverse collection of organisms should be placed in a single group. It is the least controversial of the groups presented.

·        Amoebozoa as a Clade is based principally upon comparative molecular data. Members vary widely in morphology. The name is derived from their ability to change shape..

·        •       Opisthokonts -Comparative molecular and cellular morphology data support the Opisthokonts as a clade. The name is derived from the common feature of a flagellum, when present, being located at the "rear" of a moving cell (opisthios-rear, posterior, kontos-pole).

·        Parazoa

·        The organisms included in this group do not have true tissues (See Eumetazoa). However, parazoan's structural organization shows a definite pattern, and that pattern is often one of layers.

·        Eumetazoa

·        These organisms have true tissues. A true tissue is defined as a group of cells, generally having the same morphology and organized in such as way as to perform a common function. 

·        Radiata

·        Radiatans show radial symmetry or some variation of radial symmetry. They are also diploblastic, meaning that only two layers of cells form in the developing embryo. All adult radiatan cells are derived from one of these layers.

·        Bilateria

·        These organisms show bilateral symmetry or some variation of bilateral symmetry. They are also triploblastic, meaning that three layers of cells form in the developing embryo. All adult bilaterian cells are derived from one of these

·        Acoelomates

·        Any organism that is bilaterally symmetrical, triploblastic and does not have a body cavity is an acoelomate/

·         Pseudocoelomates

·        Organisms that are bilaterally symmetrical, triploblastic, and have a body cavity that is not entirely lined with cells from the mesoderm are placed in this group

·        Coelomates

·        The organisms included in this group are bilaterally symmetrical, triploblastic, and have a body cavity that is entirely lined with cells from the mesoderm

·        Protostomia

·        These organisms are bilaterally symmetrical, triploblastic coelomates in which the mesoderm (middle tissue layer) originates from cells near the blastopore

·        Lophophorates

·        Three animal phyla have developmental and molecular characteristics that are ambiguous. They possess characteristics of both Protostomia and Deuterostomia. Their placement in Figure 1-2 is highly controversial and since all possess a feeding structure called a lophophore, they are labeled Lophophorate (consistent with traditional classifications).

·        Deuterostomia

·        These organisms are bilaterally symmetrical, triploblastic coelomates in which the mesoderm (middle tissue layer) originates from cells at the end of the primitive gut opposite the blastopore

·        Gnathostomata (Craniata with jaws)

·        Tetrapoda (four-limbed vertebrates)

·        Amniota (tetrapods with embryos having extraembryonic membranes)

Marine Plants

Lecture Note to download  

Members include seaweeds, sea grasses, mangroves, marsh grass, microscopic algae etc. If you don't include blue-green algae (prokaryotic)

• they are eukaryotic
• contain organelles enclosed by a membrane
• photosynthesis takes place in chloroplasts--green,brown, or red organelles.
• lack flowers, roots stems and leaves.

While most are referred to as plants, some have flagella and show animal characteristics...and some are actually claimed by both botanists and zoologists as theirs! Taxonomically, a compromise has placed them in the Kingdom Protista..the unicellular forms.

Seaweeds...dominant marine plants containing chlorophyll and additional pigments from blue to red. Seaweeds (exc. noted) are all eukaryotic and most are multicellular but even some that are unicellular or simple filaments are considered seaweed because the classifications of seaweeds is based not only on structure, but also on other features such as types of pigments and food storage products.

Classification characteristics used to classify are;

• 1. form which starch is stored
• 2. composition of cell wall
• 3. presence of motile with flagella
• 4. level of complexity
• 5. sometimes, reproductive patterns (reds)

Red Algae is Rhodophyta
Green Algae is Chlorophyta
Brown Algae is Phaeophyta

Algae are Thallus, meaning they lack true roots, stems, and leaves, fruits, connecting tissue etc. and photosynthesis occurs throughout the plant, not just the leaves.

Parts: Holdfast, stipe, blade, air bladders (pneumatophores). (list functions)

Brown Algae...Phaeophyta..microscopic to 60' make up the largest and structurally most complex. Colors range from olive green to dark brown, due to yellow pigments fucoxanthin dominance over chlorophyll. Pigments are xanthophyll and carotene and chlorophyll.

The simplest brown algae have a finely filamentous thallus as in Ectocarpus. There is the fan shaped Padina. Many species of brown algaes are found in the intertidal zone and known as rockweeds and in deeper areas of the cool coastal zones are the kelps, the largest and most complex of all brown algaes. As mentioned before, kelp plays an important i the coastal production with many organisms finding homes around the kelp beds. Some kelps consist of a single blade, Laminaria, which are harvested for food. Kelps have been estimated to grow up to 50 cm (20 inches) per day. Note these have the pneumatocysts.

Alginic Acid, a gummy, slimy layer in cell wall, is used as an emulsifying agent (algin)..(Know uses)

Red Algae..Rhodophyta has more species of these than green and brown combined. It has the highest commercial value, and don't get as large as brown algae.

• absence of flagellate stages
• presence of other pigments mainly phycobilins
• floridean starch as food reserve (scattered throughout cells)
• Existence of special female cells (carpogonia) and male gametes (called spermatia) for sexual reproduction.
• Cell walls with inner rigid component and outer mucilage or slime layer. This is like the alginates and very valuable.
• They can also deposit calcium carbonate (lime) into the walls of some species (Coralline algae) (Coralline algae)<

Coralline Algae

The structure of the thallus of red algae does not show the wide variation in complexity and size that is observed in brown algae. Most reds are filamentous but thickness, width and arrangement of the filaments vary a great deal. There are many variations in the shapes, sizes colors etc. of the reds. One important in marine environments are the red alga Corallines. These are characterized by deposits of calcium carbonate around their cell walls. These can be encrusting on the rocks or articulated, branching plants, with colors from light to reddish pink-white when dead. Warm water corallines are active in reef development.

Green Algae CHLOROPHYTA. The great majority of green algae are restricted to fresh water and terrestrial environments. Only 10% are marine but they are dominant in environments with wide variations in salinity such as bays and estuaries, tide pools (sewage outfalls) . ..stock from which land plants derived and in full agreement in regards to pigment, starch, cellulose etc. May exist as single cells, simple or branched filaments, blades, organized into tubes that are intertwined and usually grass green in color.

Few green algae are as complex as the other groups but their pigments and food reserve are the same as in higher plants. (evolved from green algae.) chlorophyll b in green and land but not other algaes). They are unicellular, filamentous multicellular, shapes can vary in the same species according to their environment. Enteromorpha is a thin hollow tube, Ulva, sea lettuce is leafy-like, Valonia, forms huge spheres /clusters of them in tropical waters., some branch and Caulerpa and Cladophora have tubes with many nuclei, spongy, branching thallus Codium and segmented with deposits of calcium carbonate in their walls to ward off predators but end up cementing the reef together in reef areas...Halimeda... a Coralline green algae!

Life Histories of seaweeds involve an alternation of gamete producing phase (gametophyte) and spore producing phase (sporophyte). (Video of Gamete release)

Green algae...Ulva (sea lettuce) have two identical phases. 1. Sporophyte (diploid) produces flagellated zoo spores (haploid) (meiosis) and these 2. swim briefly and settle on the bottom and 3. grow into a gametophyte phase (male or female) and produce motile gametes which 4. fuse to form zygotes (diploid). ....Codium, another green algae is more like animals and produces gametes by meiosis which fuse and form a zygote and grows into the familiar plant.

Brown algae...Nereocystis (bull kelp). The kelp is the sporophyte or diploid phase and

• 1. certain areas of the fronds (sori) become darker
• 2. meiosis occurs and haploid zoo spores are formed.
• 3. They settle to the bottom and grow into microscopic gametophytes.
• 4. The female produces eggs but holds them and the male produces sperm which are released and
• 5. attracted to eggs, fertilize them and
• 6. zygotes are formed which germinate into the sporophyte plant.

Kelp (how are chances for fertilization increased?) ....Fucus, another brown algae or rockweed, is again, like animals where the

• 1. diploid plant forms gametes through meiosis
• 2. fertilization occurs
• 3.the zygote immediately germinates back to the sporophyte

Gametes are produced in cavities called CONCEPTACLES.

Red algae Porphyra or nori is a valuable food source but has an atypical life history with the gametophyte being the large leafy plant and the sporophyte being the tiny "conchocelis" found living in discarded shells. The Typical red cycle is that of Polysiphonia.

• 1. Sporophyte produces tetrasporangia (site of meiosis) which produce 4 haploid tetraspores.
• 2. Gametophytes grow from the spores and their gametes (spermatia and carpogonia) fuse and
• 3. are retained and develop into a special mass of diploid cells (the carposporophyte)
• 4. which breaks up into many carpospores (diploid) and
• 5. these grow into a sporophyte generation which resembles the gametophyte (isomorphic) and..(go to 1)
• Red Algae Plocamium corallorhiza and an encrusting Ralfsia verrucose

Marine Angiosperms (flowering plants)...few occur in the marine environment but those that do are usually very productive and adapted for their lifestyle. Of the 3 groups, mangroves, marsh grass and seagrass, only the sea grasses are adapted to live completely submerged in water. Pollination occurs under water.

Seagrasses are not grasses, and thrie closest relatives are probably lilies. Pollen is carried by water currents and seeds are dispersed by water currents and feces of fish and other animals that browse of the plants. Eel Grass (Zostera) is the most widely distributed of the 50 species and found in shallow, well-protected coastal waters such as bays and estuaries. It has distinct flat ribbon like leaves. Surf grass (Phyllospadix) is on rocky coasts exposed to waver action. Turtle grass (Thalassia) is common in the keys. ( Manatee Grass (Halophila)).

Mangroves..80 unrelated species of flowering plants adapted to various ways to survive in the salty environment. Mangroves have a special root system using aerial roots to ventilate the system below the substratum (especially in anaerobic mud and under water). Some genera have seeds that germinate on the parent plant and drop as seedlings rather than seeds.

Saltmarsh plants, true members of the grass family, usually consists of succulent shrubs and herbs and grass-like species which can tolerate large salinity fluctuations. Cord grass inhabits the zone above the mud flats and can be submerged, and have salt glands to get rid of excess salt. Halophytes are found in higher levels of the marsh (pickleweed).

Phytoplankton...plankton..Greek for wanderer meaning that they are passively transported. Nekton are those that swim. Size categories of plankton:

• ultraplankton: less than 2 um
• nanoplankton: 2-20 um
• microplankton: 20-200 um
• macroplankton: 200-2000 nm
• megaplankton: greater than 2 mm

Types:

• Holoplankton...spend entire life in open waters
• Meroplankton...spends part of life as plankton and part as a benthic or bottom dweller.
• Tychopelagic...normally attached but break off and can then be found in the plankton.

Divisions

• Cyanobacteria (Cyanophyta) Blue-green algae (Monera)
• Chlorophyta green algae
• Chrysophyta golden algae/silicoflagellates
• Haptophyta coccolithophores
• Xanthophyta yellow-green algae
• Bacillariophyta diatoms
• Dinophyta (Pyrrophyta) dinoflagellates & zooxanthellae
• Cryptophyta cryptomonads
• Euglenophyta euglenas

Division Cyanophyta/Cyanobacteria Blue green Algae are prokaryotic cells specialized to carry on photosynthesis. Chlorophyll, phycobilins, phycocyanin, beta-carotene and xanthophylls are the pigments so color range is great..red, blue-green, black, olive, yellow, violet. The only other prokaryotes that carry out photosynthesis are some Autotrophic bacteria. There are hemosynthetic bacteria too that release stored energy in chemical compounds (H2S) . Blue-green algae contain a bluish pigment, PHYCOCYANIN. (Considered bacteria). Photosynthesis occurs on folded membranes within the cell (rather than chloroplasts). They do produce O2 etc. and probably played a role in the oxygen in the atmosphere. The presence of this ultraplankton is only being discovered .

Responsibilities of blue greens include forming dark crusts along wave splashed zones , exploiting polluted sediments and even forming a few types of red tides (Trichodesmium erythraea).(skin rashes). Blue-greens also carry out nitrogen fixation in the oceanm, converting N into nitrates to be converted to proteins. Some blue-greens live on the surfaces of seaweeds and sea grasses (epiphites) and some are known to lose their ability to photosynthesize, becoming heterotrophs.

Chlorophyta..few marine planktonic reps. but lots of macroscopic, benthic types

. Chrysophyta...golden/yellow color because in addition to chlorophyll. a & c there is a dominant carotenoid, fucoxanthin and many members have a cell covering of small siliceous scales. The silicoflagellates have an internal glass skeleton. Rare today.Characterized by star shaped internal skeleton made of silica and a single flagellum.

Haptophyta.. or Coccolithophorids, flagellated spheric cells covered with button like structures called coccoliths made of calcium carbonate. This was broken off the above class because of different types of flagella. Phaeocystis forms gelatinous clumps, visible and can effect migration patterns of fish. Also, blooms long ago followed by anaerobiosis, caused them to sediment and gave rise to oil deposits in the North Sea. The coccolithophores have small calcareous plates covering them and the patterns go way back in fossil records and are used by oil companies.

Xanthophyta...like Chrysophyceae but have no fucoxanthin pigment.

Euglenophyta...euglena..class contains only unicellular flagellates, chlorophyll. A and B and a flexible cell covering...no wall!

Fungi There are at least 500 species of marine fungi, most which are decomposers of dead organic matter. Some are parasites causing diseases in fish , shellfish, seaweed and sponges. Also some form associations with algae forming lichens and marine lichens may be found as thick, dark-brown/black or even orange patches on the wave splashed zones on rocky shores.

Bacillariophyta...diatoms...most important group in terms of primary productivity. The characteristic yellow-brown color is due to CAROTENOID pigments in addition to two types of chlorophyll (a and c). Half of the 12,000 species are marine. The brownish scum in a fish tank consists of millions of diatoms.

Diatom Characteristics

• 1. Usually unicellular but chains do occur
• 2. Pigments chlorophyll. a & c and fucoxanthin (gold/brown)
• 3. Food reserve is chrysolaminarin and oils (buoyant)
• 4. Only flagellate cells in reproduction (uniflagellate.)
• 5. Walls made of glass called frustule.
• 6. Looks like petri dish
• 7. Two symmetries..radial and bilateral which divide diatoms into 2 sub-divisions..Centric & Pennates

Reproduction...valve to valve...one product of the division retains the parental epivalve (top) and the other the parental hypovalve (bottom) which results in the bottom being slightly smaller than the parent because a new inside always grows back. Continued vegetative reproduction reduces the size until it gets to its smallest size and this diploid cell produces gametes which fuse to form a full size zygote. Only the small cells will undergo sexual reproduction and if they get too small, they can't even do that.

Dinophyta /Pyrrhophyta or the Dinoflagellates Mostly unicellular with 2 unequal flagella , one that wraps around a groove in the middle of the cell, and the other that trails free, and include the non-motile zooxanthellae (found in corals). The are most abundant in warm waters and second to diatoms in cold water.

Characteristics of Dinoflagellates

• 1. Most are marine
• 2. Chlorophyll a, c, peridinin. Starch, oils , but can ingest food stuffs
• 3. Distinctive flagella pattern
• 4. Some without walls (naked) and others with walls (Armor) with cellulosic plates fitting together like armor which may have spines,
• pores or other ornaments.(pattern and shape of plates used in classification)
• 5. Half are colorless, some heterotrophic, sparophitic, phagocytic, parasitic and some photosynthetic. It is thought that through
• evolution they have gained the ability to function as primary producers by "capturing" and using chloroplasts from other algae.
• 6. some bioluminescent
• 7. some responsible for red tides and 20 spp.. secrete toxins. They reproduce by simple cell division and form blooms that often color
• the water red, redish-brown, yellow or unusual shades.
• a. all toxic ones are photosynthetic
• b. all are estuarine or neritic forms
• c. all probably produce benthic, sexual resting stages
• d. all capable of producing monospecific blooms (suggest competitive advantages through exclusion
• e. all produce bioactive-watersoluable or lipid soluble toxins that are hemolytic, or neurotoxic in activity. (NSP, PSP, Dsp)

The Zooxanthellae are a variety of dinoflagellates which have developed a close association with an animal host. The hosts range from sponges to giant clams but the most important are the ones in the stony corals. They help fix carbon through photosynthesis, release organic matter to be used by the coral, help in formation of the coral skeleton.

THE IMPORTANCE OF CORALLINE ALGAE

(from Nongeniculate coralline algae @ http://196.21.43.2/clines.htm)

Corallines as carbon stores

Coralline algae take up carbon for use in the process of photosynthesis, as do most plants, but they have an additional mechanism of carbon uptake, the calcification process. Calcium is deposited in the cell walls of coralline algae in the form of calcium carbonate. One of the most exciting pieces of information which I have recently received came from a Brazilian marine biologist, E.C. de Oliveira, who has presented evidence that coralline algae may be one of the largest stores of carbon in the biosphere. If this is so, then they urgently need to be studied, since we know so little about even their basic ecology, particularly in the Indo-Pacific region.

Corallines in community ecology Many corallines produce chemicals which promote the settlement of the larvae of certain herbivorous invertebrates, particularly abalone. This is adaptive for the corallines as the herbivores then remove epiphytes which might otherwise smother the crusts and pre-empt available light. This is also important for abalone aquaculture, as corallines appear to enhance larval metamorphosis and the survival of larvae through the critical settlement period. It also has significance at the community level, as the presence of herbivores associated with corallines can generate patchiness in the survival of young stages of dominant seaweeds. I have seen this in eastern Canada, and I suspect the same phenomenon occurs on Indo-Pacific coral reefs, yet nothing is known about the herbivore enhancement role of Indo-Pacific corallines, or whether this phenomenon is important in our coral reef communities.

Some corallines slough off a surface layer of epithallial cells, which in a few cases may be an anti-fouling mechanism which serves the same function as enhancing herbivore recruitment. This also affects the community, as many algae recruit on the surface of a sloughing coralline, and are then lost with the surface layer of cells. This can also generate patchiness within the community. The common Indo-Pacific corallines Neogoniolithon sp. and Sporolithon ptychoides slough epithallial cells in continuous sheets which often lie on the surface of the plants looking so much like wet tissue paper. Not all sloughing serves an anti-fouling function. Epithallial shedding in most corallines is probably simply a means of getting rid of damaged cells whose metabolic function has become impaired. Sloughing in the South African intertidal coralline algae, Spongites yendoi, was studied and it was found it sloughs up to 50% of its thickness twice a year. This deep-layer sloughing, which is energetically costly, does not have any effect on seaweed recruitment when herbivores are removed. The surface of these plants is usually kept clean by herbivores, particularly the pear limpet, Patella cochlear. Sloughing in this case is probably a means of getting rid of old reproductive structures and grazer-damaged surface cells, and reducing the likelihood of surface penetration by burrowing organisms.

Some coralline algae develop into thick crusts which provide microhabitat for many invertebrates. For example, off eastern Canada, ,juvenile sea urchins, chitons, and limpets suffer nearly 100% mortality due to fish predation unless they are protected by knobby and under-cut coralline algae. This is probably an important factor affecting the distribution and grazing effects of herbivores within marine communities. Nothing is known about the microhabitat role of Indo-Pacific corallines. However, the most common species in the region, Hydrolithon onkodes, often forms an intimate relationship with the chiton Cryptoplax larvaeformis. The chiton lives in burrows that it makes in H. onkodes plants, and comes out at night to graze on the surface of the coralline. This combination of grazing and burrowing results in a peculiar growth form (called castles) in H. onkodes in which the coralline produces nearly vertical, irregularly curved lamellae.

Non-geniculate corallines are of particular significance in the ecology of coral reefs, where they provide calcareous material to the structure of the reef, help cement the reef together, and are mportant sources of primary production. Coralline algae are especially important in reef construction, as they lay down calcium carbonate as calcite. Although they contribute considerable bulk to the calcium carbonate structure of coral reefs, their more important role in most areas of the reef, is in acting as the cement which binds the reef materials together into a solid and sturdy structure.

An area where corallines are particularly important in cobnstructing reef framework is in the algal ridge that characterizes surf-pounded reefs in both the Atlantic and Indo-Pacfic regions. Algal ridges are carbonate frameworks that are constructed mainly by nongeniculate coralline algae (after Adey 1978). They require high and persistent wave action to form, so are best developed on the windward reefs in areas where there is little or no seasonal change in wind direction. Algal ridges are one of the main reef structures that prevent oceanic waves from striking adjacent coastlines, and they thus help to prevent coastal erosion.

Economic importance

Despite their hard, calcified nature, coralline algae have a number of economic uses. One use dates back to the 18th century, and involves the collection of unattached corallines (maerl) for use as soil conditioners. This is particularly significant in Britain and France, where more 300 000 tonnes of Phymatolithon calcareum and Lithothamnion corallioides are dredged annually. Several thousand kilometres of maerl beds, composed of as-yet undetermined species belonging to the genera Lithothamnion and Lithophyllum, exist off the coast of Brazil, and have been subjected to a low level of commercial exploitation. Maerl is also used as a food additive for cattle and pigs, as well as in the filtration of acidic drinking water.

Corallines are also used in medicine, where the earliest use involved the preparation of a vermifuge from ground geniculate corallines of the genera Corallina and Jania. This use stopped towards the end of the 18th century. Modern medical science has found a more high-tech use for corallines in the preparation of dental bone implants. Apparently, the cell fusions provide an ideal matrix for the regeneration of bone tissue. Since coralline algae contain calcium carbonate, they fossilize fairly well. They are useful as stratigraphic markers of particular significance in petroleum geology. Coralline rock has also been used as building stones, with the best examples being in Vienna, Austria.

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Marine  Mammals

Lecture notes  

Anyone who has ever witnessed the early morning feeding at sea on a calm day has also seen the superiority of the warm-blooded physiology over the cold-blooded way of life. While the sardines, anchovies and other schooling fry are chased around by faster fish, sea birds, like dive bombers take their share of the feast. But even the predators, bonitos and bass, are easy prey for the second circle of divers, the dolphins. Sharks roam farther away to scoop up remains but don't venture in too close because of the dolphins...from the air and from below, the fish are no match for the warm-blooded birds and mammals.

The warmer the blood the higher the efficiency of the living thermodynamic machine. Birds and sea mammals have acquired their power while evolving out of the oceans; their physiology has coped with such problems as keeping their central temperature constant or holding their breath during deep, prolonged dives. The heat exchanging system present in their flukes, fins, wings, or webbed feet is ingenious. Some powerful fish, tuna, have also developed this system but this is only to keep their muscles a few degrees warmer than the surrounding water while the marine mammal and bird must keep their temperature constant whatever outside polar or tropic temperatures may be.

 

The warm blooded animals have no feeding problem. They have to eat a lot more compared to the same size fish. Colonies of millions of seabirds pile up on islands, feeding twice a day in less than half an hour and gorging themselves to a point of hardly being able to fly. In the sea, whales fill up on crustaceans in a few daily dives, pilot whales dive deep and fill up on squid or cuttlefish, and porpoises and dolphins and sea lions spend less than an hour a day to quench their appetite.

Having no difficulty in finding food, these warm blooded animals have lots of leisure time, explaining why they play, travel for no apparent reason and some, like the sea elephant, are so fat that they can afford to fast for several months when they come ashore to breed.

Leisure time has been used by the sea mammals that have a large brain to develop wit, intelligence, communication, and even some unnecessary feelings such as faithfulness, tenderness, and friendship.

 

This warm-blooded superiority has some severe limitations. Because of the high combustion of the excess food, excess oxygen is also needed (from the air) and this limits the duration of their dives. Some birds and cetaceans have modified their organs to perform dives of extended duration.

 

No birds, except the penguin, is at home in the sea like the pelagic mammals but many spend their life at sea except form that one short period of the year when they come ashore to mate, nest and raise their young. Whalebirds, prions, sea hawks, jaegers, and the albatrosses and shearwaters are among these pelagic birds. Other birds live in open waters just offshore, coming ashore little more than pelagic birds but remaining closer to land. (sea ducks) and some remain close to shore and seek haven in stormy weather on land or in shoreside ponds. (gulls terns, skimmers.)

 

The largest group of marine mammals are the Cetaceans. There are over 90 species. These have the most complex transition to marine life.

Cetaceans are shaped like fish but are not fish. There are 90 different species . They are all marine except a few freshwater dolphins. They are all totally dependent on support afforded by the water and can't survive on land. The whales, dolphins and porpoises are born live, suckle their young, and breath air. From the 4 ft. harbour porpoise to the 110ft blue whale these mammals have no need to come on to land. They have a pair of front flippers, but the rear limbs have disappeared and though there are rear limbs present in the embryo, they are small useless bones in the adult. There is a dorsal fin and the tail ends in a pair of fin like horizontal flukes. Blubber provides insulation and buoyancy and body hair is almost absent. The nostrils form a single or double opening called a blow hole on the head

There are two sub-orders...Odontoceti (toothed whales) equipped with pegshaped, spadelike teeth for grasping food, using biosonar or echolocation to locate prey at great depths (sperm whale) and include toothed whales, dolphins, porpoises and killer whales.

The second sub-order is Mysticeti (mustache G) or toothless baleen whales which scoop up minute plankton and small drifting fish with overlapping flaps of baleen (made of similar material as your hair and nails. They feed by taking in a big mouthful of water, squeezing it through the bristles and licking the food left behind. Included are the blue whale and divide into three families; rorqual whales...blue, humpback, fin, sei, Byrds and minke which feed on dense swarms of krill, 2. Right whales inc. black, Greenland, pygmy which feed on swarms of Copepods and the 3. gray whale which feed on worms, small crustaceans and other bottom organisms by sucking up sediments and filtering its food from the mud.

 

Pinnipeds, seals, sea lions and walruses while they need to come ashore to breed, they go to sea only to feed. They evolved from early forms of terrestrial carnivores/cats,dogs,bears and they are all predators. They also have blubber which acts as insulation, food reserve, and buoyancy. There are 19 species of seals, distinguished by having rear flippers that cannot move forward. On the land they pull themselves forward with their front flippers. Elephant seals are the largest with males reaching up to 20' in length. Monk seals live in warm regions, the exception to the relatively cooler regions where seals inhabit.

Sea lions or eared seals are similar to seals except they have external ears and can move their rear flippers forward so they can use all 4 limbs to walk or run on land. The head of the sea lions look doglike while the seals look more like a cat. There are 5 species of sea lions and 9 related fur seals.

Walrus is a large pinniped with a pair of distinctive tusks protruding down from the mouth. It feeds mostly on invertebrates, clams but there is no evidence that the tusks are used to dig up the clams and they travel along the bottom sucking up their food, with their stiff whiskers acting as feelers.

Sea otters, the member of Carnivora, the smallest of the marine mammals. They lack blubber and their fur traps air there to act as a layer of insulation.

Sirenia- dugongs and manatees, descendants from elephants, sluggish, with forearms modified as flippers and no hind limbs, may have been the source of the mermaid legend, thus the name Sirenia ( sailors probably had been at sea too long)

 

Adaptations;

Streamlining..in the evolutionary process of streamlining the shape, cetaceans have undergone a distortion of their skulls so the nostrils are pushed back atop the head. This enables the animal to breathe at the surface without lunging out of the water. It only needs to break the seas surface with the top of its head, open the blow hole quickly and exhale, then inhale quickly, close its blow hole, and submerge. It takes only two to three seconds and may be repeated several times before a deep dive. In large whales the moisture of their warm breath condenses when it hits the air and together with a little mucus and seawater a characteristic spout or blow which sometimes can be used to identify the whale. Cetaceans have all but lost their necks as the cervical vertebra are compressed and blubber fills in the natural constriction behind the head.

Adaptation of bones that make up the flippers

Bones in cetaceans are also lighter as a result of being buoyed up by water and blubber. Beached cetaceans can suffer serious injuries because of the lack of support.

Seals: Eared seals (Otariidae) including fur seals and sea lions use front flippers for swimming and can turn their hind flippers forward to walk on land, have visible ear flaps and usually found in warmer waters. True seals (Phocidae) are propelled through the water by their hind flippers and these can't support their weight on land and get drug helplessly behind.

Walruses (Odobenidae) use both front and hind flippers for swimming. The upper canine teeth in both males and females develop into large tusks used to hoist them onto the ice and dig clams and mussels in 300'water.

Sea Otters (Mustelidae) uses stone tools when it feeds cradling them on their abdomens and smashing open shells of clams or sea urchins. They also have no blubber and with dense fur and oil secreted from numerous glands, a layer of air is trapped under the fur to prevent excessive loss of heat. Also otters eat urchins which feed on holdfasts (supporting structures of kelp) and have helped kelp forests survive. With the decreased population of otters, the kelp forests showed marked destruction.

Polar bears (Ursidae) Have white fur to help them blend into the snow/ice around them, possesses thick fur a layer of insulating hair on their paws, and a thick layer of blubber and are streamlined more than other bears to help them swim better.

 

Streamlining in birds allows them to pass through the air and water with least effort and best fuel economy. Gannets are quick strong flyers and can dive into the water going down 30 feet to capture their food.

 

Fur, except in otters which trap air bubbles under their fur, is generally used for insulation in the air . Most marine mammals have to depend on blubber for insulation. Blubber is a thick layer of fatty tissue between the skin and muscles. The amount depends on the species and the season. Species living in ice latitudes have thicker blubber than those in warmer latitudes. Its buoyant and helps keep whales and dolphins afloat. Right whales have blubber 28" thick and float when killed. Besides insulation, its a food reserve. Whales feed on fatty shrimp-like krill in colder waters and as they move to warmer waters where food is less abundant, they draw on their blubber as food reserves, thinning their layer out.

Pinnipeds have a fat layer usually thinner than cetaceans (3"). Male fur seals when they come ashore to breed, have flaps of fat hanging from them but after the season, are relatively thin. During nursing, females draw from these reserves for milk production.

 

Birds also have fatty tissue within them that serve as a food reserve when they are migrating. With little time to eat when heading towards their feeding grounds, they get their energy from their reserves. (duck hunters know there are fat deposits on the ducks in the early season but not late in the season)

Teeth -- Dolphins and porpoises and sperm whales are well equipped with teeth 42-300) They use them to hold their quarry not to chew.

Rorquals have bony plates with hairy edges inside their mouths instead of teeth. The plates are called baleen and are made of the same substance as our hair and fingernails. They feed by straining the food out of the water, swimming with their mouths open.

Seals and sea lions also use their teeth to hold their prey rather than chew while manatees use lips to gather plants that make up their diet.

Bird bills range from the huge bill and pouch of the pelican to tiny bills of the sandpipers to the broad bill prion which has strainers on the edges of the bill like baleen.

 

Ears Most Marine mammals have no external ears but fur seals and sea lions do but they lay back while swimming. Small openings mark the ears in birds and true seals. In cetaceans and sirenians, a crease shows where the ear is.

 

Nostrils Cetaceans have nostrils (blow hole) on the top of their heads. Toothed cetaceans have had both nostrils merge as one blow hole which remains sealed during its dive. The sperm whale the nostril has its blow hole located on the left side of the head. Pinnipeds have nostrils that close when relaxed so they, like cetaceans must make a conscious effort to breathe.

 

Water Fish eating dolphins get their water from the fish they eat, Orcas, feeding on birds and mammals, get water from them but both groups take in some seawater with their food. Seals and sea lions take no seawater in with their food but whales walrus and sea otters eat invertebrates whose body fluids are close to the salinity of sea water. One reserve is the fat because when it is burned up, water is a by-product.

Water conservation. Cetaceans have no sweat glands and lose little water to the atmosphere when breathing because of the humid air near the surface of the sea. Kidneys also dispose of excess salt.

Birds have a pair of glands near the nasal passages in the head which help secrete excess salt. These are found in all birds but not always functional and usually only work when excess salt is present (after feeding).

 

Temperature control:

Body temp. regulation in most marine mammals occurs through the flippers/forelimbs, and flukes or hind limbs. These flattened hands/feet are thin sheets of flesh with no blubber but are abundantly irrigated and allow cooling of the blood. Each artery that feeds these limbs is surrounded by veins that join to form a sheath through which the blood returns to the heart. The blood in the veins, cooled by having circulated in the cold limb, is warmed by the transfer of heat from the arteriole blood, which is cooled in the process. As the venous blood returns to the heart it is progressively warmed and there is little heat loss to the outside of the body, as the flipper/fin is irrigated by blood that is already cold. To the other extent, the venous blood can bypass the heat exchanger and return through another network of veins close to the skin that have no insulation.

The rest of the body is insulated by a layer of blubber and the peripheral blood circulation can slow /reduce during each dive.

Seals use their skin as a heat exchanger opening or closing tiny blood vessels in the skin capable of exchanging heat with the air. Sea otters are the least adapted but has developed a way to use the properties of its coat to trap small air bubbles which engulf the otter when it dives.

Birds with their greased feathers can control individual feathers in positions that allow precise degrees of ruffling to imprison air either before or after a dive. The feet can cool the animal off easily if needed or to retain heat, be retracted within the belly feathers.

 

Digestion The marine birds and mammals swallow their food whole, none is equipped for chewing.These whole shrimp, fish etc. are dissolved by gastric juices and possibly ground up by gravel and stones in the stomach or crop.

Cetaceans have a three part stomach (cattle etc.) with the 1st part a great widening of the esophagus. In whales this part has stones to grind up food. the second section of the stomach is like the human stomach, secreting HCl and pepsin. The third stomach is smoothed-walled but has a few glands that secrete digestive juices. Rorquals can hold up to a ton of krill in the 1st two stomach sections. After the stomachs, the food then passes to the small and large intestines.

Pinnipeds also have stones in their stomachs but one mystery is the huge length of their intestines which is usually short in carnivores/ its 3x longer than a cow.

 

Breathing: Cetaceans exhale up to 80-95% of the air in their lungs (man 15-25%) and pinnipeds about 35%, sirenians, 50%. Exceptional development of the diaphragm muscles (compared to man) in cetaceans and more floating ribs, may give them a more flexible and powerful breathing pump. It takes a rorqual two seconds to exhale and inhale 1500 gallons of air and man 4 seconds to exhale and inhale a pint.

Diving: When mammals dive, the heart beats slower (bradycardia) 15-50% slower, and blood supply to less essential areas of the body is shut off by sphincter muscles in some arteries ( goes to heart, brain, lungs, muscles not stomach and kidneys). By shutting down, less O2 is needed for the dive. Oxygen is also not stored as a gas but is either accumulated as chemical combinations as oxides in blood or muscles or dissolved in organic liquids and tissues.

Cousteau, The Ocean World, Chp 9 pp 196-210, 1979.

 

Special adaptations include substantial amounts of myoglobin and large volumes of blood. Myoglobin in the muscle tissues binds a large amount of oxygen. The large pool of blood allows for a storage place for Oxygen. the blood is also a storage site for glucose (more because more blood). Small twisted blood vessels forming spongy masses in fatty tissue (retia mirabilia) seem to regulate blood pressure during the dive so brain, heart and lungs are supplied with constant blood pressure. The pressure on the blood stored in the RM forces blood into the vital organs.

 

During deep dives, the outside pressure squeezes their ribs as the volume of air in the lungs decrease. The ribs of many diving mammals are designed to collapse inwardly. Human divers as they dive deeper, take air in under the pressure which dissolves in their blood. As they ascend, this gas must get out of the solution in the blood or air bubbles will form , embolism or the bends. cetaceans take very little air down in their lungs, rather it is in solution as above and it can't expand beyond its original volume when ascending because the original volume was taken in at the surface rather than at the bottom under pressure.

 

Using Oxygen, glucose is broken to CO2, water and energy but once the O2 is used up, glucose is broken down anaerobically to lactate releasing a little energy, so they can use glucose in a mixed anaerobic/aerobic metabolism..one of the most important modifications ...oxidize lactate!

 

Echo-location and vocalization

Because their sense of smell is so limited, any marine mammals have developed echolocation, natures version of sonar. The animal emits sound waves which travel 5x faster in water and listens for echoes reflected back from the surrounding objects. The echoes are analyzed by the brain. Most toothed whales , some pinnipeds and some baleen whales may also echolocate. (Bats Too)!

The sounds of echolocation consists of short bursts of sharp clicks repeated at different frequencies. Low frequency clicks have high penetrating power and can travel long distances. The clicks, squeaks and whistles of cetaceans are produced and air is forced through air passages and air sacs while the blow hole is closed..no vocal cords so the frequencies are changed by contracting and relaxing muscles along the air passages and sacs. A fatty substance on the forehead, the melon appears to focus and direct sound waves..this gives them the rounded forehead. In toothed whales incoming sound waves are received primarily by the lower jaw. Ear canals are reduced or blocked in most cetaceans. The jawbone is filled with fat and oil and transmits sound to the two very sensitive inner ears...each independently.

Behavior..the brain has evolved into complex behaviors like learning..not instinct dominates...they rely on past experiences.

Most live in groups at least part of the time. Vocalizations play a prominent role in communications loud barks, whimpers, sedate grunts, whistles, chirps, moos, barks...there have been over 70 calls identified of the killer whales. and there are different dialects. Cetaceans show play behavior and the great whale breaches, some stick their heads out of the water to spy.

 

Migration

Most migrate from cold polar waters to warmer areas in response to amount of food. In the fall, the food in the polar waters becomes scarce and most cetaceans migrate to warmer waters. The pacific gray whale migrates 11,000 miles from the Aleutian to the Baja Peninsula.

 

Reproduction

Migration and reproduction are closely interrelated: and adaptations are...birth of seal pup must be exactly timed to coincide with the mothers return to the breeding area 11 months later because the pup would drown if born at sea. Whales must reach war water prior to giving birth. Therefore, gestation must be timed exactly.

In certain fur seals, the period is lengthened by stopping development of the embryo for several months. The embryo does not attach to the wall of the uterus after descending from the fallopian tube. the delayed implantation of the embryo lasts 4 months. It then attaches to the wall and begins to develop. The delayed implantation enables the mother to complete nursing her pup, and gives her body a chance to build up the necessary food reserves to ensure the developing fetus will be supplied nutrients during gestation.

In streamlining the body the sex organs became internal. The penis is inside the body held by retractor muscles attached to the pelvis. Connective tissue and a penis bone or baculum keep the penis rigid. Copulation in cetaceans is belly to belly and is brief being difficult to maintain contact in the sea.

Baby whales are born tail first and guided to the surface for its first breath by its mother. Gray whales weigh 907 kg at birth and 19 ft. long. Baby blue whales gain 90 kg each day. The high fat and protein content of the milk (10x fat of cow milk) milk is pumped into the young 9.5l/2-3 sec. 50x /day makes 490 l of milk daily.

Birth rate is low one / 3 years and offspring are looked after for some time.

 

Chapter Questions

Reading

MARINA MAMMALS-ADAPTATIONS

 

ADAPTATIONS

• We’ll look at structure and mode of locomotion for major taxa before returning to the implications for

energetic costs

Polar bear

• Largest bear species, but smaller than recent ancestors

• Large feet aid in swimming

• Pulls through water with forelimbs, hindlimbs trail behind

– Position aids in pulling heavy body for swimming (climbing in other bears)

• Large paws distribute body weight on land

 

 

 

Osmoregulation

• Refers to maintaining salt (electrolytes) and water balance in internal environment

• Marine mammals are hypoosmotic

– Body fluids have lower salt concentration than surrounding water

– In danger of losing water through osmosis

Balancing salt and water

• Feeding and water ingestion alter osmoregulatory balance

– Most (or all) water ingestion from food intake

• Reestablished by urine, feces, evaporation; Kidneys are organ responsible for balance

 

Kidneys of marine mammals

– Many species have large kidneys, but not all (e.g. elephant seals)

– Kidney:body mass ratios

• 0.44-1.0% cetaceans; 0.3-0.4% terrestrial mammals

– Pinnipeds, cetaceans, polar bear and sea otter have reniculate kidney

– Many small lobes (reniculi)

– Each lobe functions as mini-kidney

– Cetaceans have 100s to 3000 reniculi in kidney

– Number of reniculi depends on salinity of diet

• Sirenian kidneys are not reniculate

 

• Dugong kidneys are elongate, smooth, and have some characteristics of ungulate kidneys

• Dugongs are physiologically independent of freshwater

• Manatees must have access to fresh or brackish water to maintain osmotic balance for prolonged periods

Drinking and water sources

• Marine mammals will drink freshwater when it is available

– Some pinnipeds in polar areas eat ice

– Is it needed? Not really

 

• Water sources

– Drinking

– Water in food

• Fish/invertebrates 60-80% water

– Water from own stores (catabolism)

• 1.07 g water/g fat; 0.4 g water/ g protein

• Used extensively during fasting

Drinking saltwater

• Allows high rate of urea production to get rid of more wastes

• Associated with high protein diet

– Need to get rid of more nitrogen

 

• Sea otters drink lots of seawater

• Cetaceans and pinnipeds will drink seawater (especially adult male otariids that have prolonged fasting)

Reducing water loss

• Few salt glands present in pinnipeds and none in cetaceans

• Reduced urine output

• Countercurrent moisture exchangers in respiratory tract

Maintaining water balance

• Water loss from exhalation can be extreme (especially on land)

– Some pinnipeds (elephant and gray seals) conserve water during breathing

– Countercurrent blood flow in the nose sets up temperature gradients

– Increased surface area in nasal passages

– Moisture in exhalation condenses on epithelium then humidifies inhaled air on way to the lungs

Adaptations: Sensory Systems

Marine mammal sensory abilities

• Life underwater presents unique challenges in trying to navigate, find food, avoid predators, and interact

 

with conspecifics due to low light and visibility conditions

• Most species rely heavily on numerous sensory systems working in concert

• Many marine mammal systems highly modified from terrestrial mammals

• In this lecture, we’ll look at all but sound production and echolocation

Mechanoreception

• Includes:

– Touch

– Hydrodynamic reception

– Sensing vibration and water disturbance

 

– Audition

– Sensing sound waves

Touch

• Other than whiskers, receptor units are distributed across entire body

• Head area most sensitive for tactile information

– Skin sensitivity in dolphins may be used to help with drag reduction, but most interest in other

species focuses on whiskers

• Most specialized mechanoreceptors are vibrissae (whiskers or sinus hairs)

– Specialized sensory hairs

– Diameter and structure reflect does not reflect importance but adaptation to signals received and

transmitted (sensitivity and function)

– Used for tactile information but may also detect vibrations

 

– Stiffer hair in pinnipeds

– Follicles surrounded by 3 (not 2) blood sinuses

• Three types of vibrissae

– Rhinal

• 1 or 2/side just posterior to nostril (phocids only)

– Supraorbital

• Above eye, mostly immobile

– Mystacial

• Upper lip, mobile

• Most prominent and numerous

• Walruses have most (600-700)

 

Pinniped vibrissae structure

– Number of nerve fibers (1000-1600) passing through capsule in Phoca hispida is 10x greater than terrestrial species with sensitive whiskers

 

• Extremely sensitive

– Baltic seal vibrissae have 10x nerve fibers of terrestrial mammals

– Size discrimination abilities of harbor seals and CA sea lions are similar to primate hands and close to visual capabilities of the seal which shows the importance of this sensory system (Denhardt andKaminski 1995)

– Move head side to side when object is small but don’t need to for large objects (touch multiple vibrissae simultaneously)

 

Pinniped Vibrissae function

• Tactile receptors

– Mystacial vibrissae used for discrimination of textured surfaces (location, shape, size, surface

texture)

• Navigation

– Can help navigation in total darkness and low visibility conditions

– Use as speedometer, sense direction changes

• Prey detection and capture

– Even blind seals found to be well-fed in wild

– Often used to scan for benthic prey

 

Cetacean Vibrissae

– Only on head along margins of upper and lower jaws

– Structure and innervation suggest sensory role

– Mysticetes have ~100 very thin (0.3 mm dia) immobile vibrissae on upper and lower jaw

– Most odontocetes lose hair postnatally; 2-10 follicles on either side of upper jaw

– Exception are river dolphins which possess many well developed immobile vibrissae on both jaws,

but not yet shown if they are true vibrissae

 

Sirenian Vibrissae

– Entire muzzle covered with flexible bristle-like hairs

– Used for discrimination of textured surfaces

– Also have perioral bristles on the upper lip, oral cavity and lower jaw that are very rigid and moveable

– Manipulation of objects, further exploration once grasped

– Manatees can control facial vibrissae which may have role in feeding

– Sinus hairs also lightly scattered over body

 

The Sirenian mouth

• Combination of muscular lips and different types of facial vibrissae form a unique system

• Manatees can use this “haptic” system in a prehensile fashion to investigate objects and manipulate food

into mouth

Sea otter and polar bear vibrissae

• Sea otters have all three types of vibrissae

– Mystacial whiskers most numerous

• Few vibrissae in polar bears

 

Hydrodynamic Reception

– Can vibrissae of pinnipeds detect pelagic fish through water disturbances? (Denhardt et al. 1998)

– Vibrissae respond to vibrations, but took an experiment to show that this worked for water

disturbances

– Vibrissae are tuned to frequency range of fish-generated water movements

– Fish leave trails of disturbance that last minutes

– Harbor seals can detect and tract trails up to 40m long (based on blind-folded seal following

minisub)

 

– Sensory abilities of vibrissae help explain success of pinnipeds in dark and murky water

Audition (hearing)

• Some changes in marine mammals

– Closing mechanisms to protect the ear from penetrating water under pressure at depth

– Loss or reduction of external ear flaps to increase streamlining

– No real tradeoff for underwater hearing since external ear tissue is acoustically transparent

underwater

• A major problem is how to transmit sounds to the inner ear and localize sources

 

Sound localization

• In horizontal plane, determined by interaural time and intensity differences

• Sound travels 4.5x faster in water so information processing must be better

!

How do marine mammals localize sounds?

• Terrestrial mammals underwater can’t localize sounds

– Bone conducts sound to both ears almost simultaneously

• Auditory organs of odontocetes are largely isolated from the skull to avoid bone conduction (less so in other MM)

– How does sound reach the inner ear in odontocetes?

Sound reception in odontocetes

 

• Two pathways

– Ear canal functions to detect low frequency sounds

– Mandible (lower jaw) can detect high frequency sounds

– Fat channels in lower jaw have impedance close to water and channel sound over pan bone to

petrotympanic bullae

Sound reception in other MM

• Mysticetes still unknown, but conventional pathway of terrestrial mammals is functional

– Distance between ears makes localization less problematic with bone conduction

 

• Manatees have lipid-filled zygomatic process which appears to transmit sound to squamosal-periotic

complex (mechanism similar to odontocetes)

Sound reception in pinnipeds

• Appear to use conventional pathway

• Bone conduction probably most important for sound transmission

– Should limit directional sensitivity with sound through skull

– good sound-localization in some sp (Phoca vitulina)

– Poor and variable in others (Zalophus califonianus)

• Ear functional in air sensitivity depends on species

– California sea lion: best in air

– Common seal: equal

– Northern elephant seal: better underwater

Hearing ranges and discrimination

• Odontocetes have widest hearing range

– Tursiops best hearing 12-75 kHz but up to 150 kHz detected

– Can discriminate frequency difference of 0.2-0.8% from 2 kHz-130 kHz

 

• Frequency discrimination is less precise and operates over a lower frequency range in pinnipeds and

sirenians

Weeding out background noise

• Marine mammals superior to terrestrial mammals in detecting signals in noise

• However, this is often not enough and vocalizations may be used to reduce masking effects

Vision

• Electromagnetic radiation changes intensity and composition as it moves deeper in water

 

– Becomes more monochromatic and spectrum shifts to shorter wavelengths as depth increases due to

scattering and absorption

• Eyes of marine mammals adapted to see in water and in air

Habitat and vision

• Spectral sensitivity of visual pigments should correspond to the habitat where vision is most important

– Deep-sea fishes have blue-sensitive pigments

– Shallow water fishes are green-sensitive

• Generally fits for marine mammals

 

– Shallow diving species green or blue-green

• E.g. spotted seal, manatee, gray whale

– Deep-diving species tend to have blue

• E.g. elephant seal, Baird’s beaked whale

– Reflects habitats as well (e.g. open ocean is bluer; arctic is greener, Weddell Seal)

Marine Mammal Eyes

• Generally resemble nocturnal mammals

– Dilatable pupil maximizes light collection

– Choroid located between retina and outer coating of eye with tapetum lucidum (light reflecting

layer)

 

– Retina dominated by rod-like receptors but cone-like receptors (or second type or receptor) strongly

suggested or verified

• Two types of cones in mammals

– S: short wavelength sensitive

– M/L: medium to long wavelength sensitive

• Absence of S cones associated with nocturnal habits

• Cetaceans and pinnipeds lack S cones, which appears to be adaptation for redder coastal waters

 

– Loss may have occurred early in evolution or should see S-cones in pelagic species (we don’t)

Do marine mammals see in color?

• Mixed results from psychophysical methods

– Demonstrated in spotted seals, California sea lions, manatees

– Failed in bottlenose dolphins

– Fur seals can discriminate blue and green but not red and yellow from grey shades

• Color discrimination and adaptive nature of vision is still unclear

 

Adaptations to seeing in water

– Cornea and encased fluids have about the same refractive index as saltwater; optically inefficient

– Refractive power restricted to lens when submerged

– Most pinnipeds and cetaceans have a large almost spherical lens with high refractive power allowing

normal vision underwater

– Trade-off: when cornea regains power in air, results in extreme near-sightedness

 

River dolphin eyes

• Most river habitats extremely murky

• Sensing light and dark for orienting to surface is all that is important

• Platanista indi and P. gangetica have lost the lens of the eye and are essentially blind

Visual Acuity

• Perception of fine detail at various distances

• Visual acuity degrades faster in air than in water

• Acuity underwater is poorer than in-air acuity of many primates, but better than many terrestrial

 

mammals with good vision

– e.g. elephants, antelope

Chemoreception: Olfaction

• Relatively little attention in marine mammals

• Relative to terrestrial mammals, marine mammal olfactory systems

– Somewhat reduced in pinnipeds and sirenians

– Very reduced in baleen whales

– Absent in odontocetes

Olfaction in pinnipeds

• Olfactory systems well-developed

• Have vomeronasal organ

– Can detect scents of food in mouth

• Olfaction may function in mother-pup recognition

• More research needed to understand role of olfaction in pinnipeds

Chemoreception: Gustation

• Taste buds in oral cavity provide information about dissolved substances

• Taste appears to be limited in pinnipeds and small odontocetes

– Fewer taste buds that terrestrial mammals

 

– They can discriminate some chemicals in sea water and can detect the four primary tastes (sour,

bitter, salty, sweet) but for most of them, detection thresholds are much higher (especially salty)

• More taste buds present in sirenians

 

Taste in pinnipeds and other marine mammals

• Use of taste in marine mammals poorly known

• May be highly specialized for detecting salinity differences at high (marine) salinities

– Harbor seals shown to be very good at this

– Could be used for finding vertical layers

– For navigation to/along oceanic fronts?

 

Ring Species

•             There are several ring species, but the most famous example is the herring gull. In Britain, these are white. They breed with the herring gulls of eastern America, which are also white. American herring gulls breed with those of Alaska, and Alaskan ones breed with those of Siberia. But as you go to Alaska and Siberia, you find that herring gulls are getting smaller, and picking up some black markings. And when you get all the way back to Britain, they have become Lesser Black-Backed Gulls.

•             So, the situation is that there is a big circle around the world. As you travel this circle, you find a series of gull populations, each of which interbreeds with the populations to each side. But in Britain, the two ends of the circle are two different species of bird. The two ends do not interbreed: they think that they are two different species.

 

 

 

Evolution and Systematics

Convergence, Divergence and Parallel Evolution

– Distantly related taxa can come to resemble one another through the process of convergence (wings)

– Closely related taxa may quickly develop very different morpholgies through divergence

– Species may have diverged in the distant past can maintain similar morphologies through parallel

evolution

Adaptations

• An adaptation is a character or suite of characters that helps an organism cope with its environment

• A preadaptation (or exaptation) is an adaptation that performs a function other than previously held

– e.g. the lower jaw of odontocetes is used to transmit high frequency sounds underwater but first

evolved to transmit low frequency sounds from the ground

Adaptive Radiation

• Rapid diversification of a lineage into many forms

• Can obscure relationships due to rapid evolutionary change if in distant past

• If recent, may be hard to detect differences: what is a species??

What is diphyly, with regards to monophyly vs diphyly?

 

•       If whales are monophyletic, that means a single common ancestor gave rise to all whales. If it is diphyletic, that means the whales have two different ancestors and that they are only similar because of convergent evolution. There are 2 great groups of whales: toothed whales and baleen whales. There is strong evidence that baleen whales evolved from a toothed whale, therefore there is strong evidence that whales form a monophyletic group

 

– Biological Species Concept

– Inability to interbreed

Studying evolutionary relationships

• Systematics – the study of defining evolutionary relationships among organisms both extinct and extant

• A phylogeny is a hypothesis about evolutionary relationships

– Often shown on a tree

– Can never be “proven” only strongly supported!!!

Phylogenetic Trees(Cladograms)

• Tree representing best estimate of phylogenetic lineages

– Lines are clades or lineages (groups of related taxa from a common ancestor)

– Nodes = branch points = speciation events

 

 

Cladistics

• Organisms can be deemed related based on shared derived characters (synapomorphies)

• Characters

– any feature useful in phylogenetic analysis

– May be ancestral (primitive) or derived (apomorphy)

– Characters may be primitive or derived but taxa are not

• Taxa are all endpoints of evolution

• Character State

– Condition of the character

Homology and Analogy

• Cladistics relies on finding synapomorphies

 

• Homology

– Characters that arise from similar ancestry

– Bats’ wing bones and human fingers

• Analogy

– Similar characters that do not share evolutionary history

• Bird wing and bat wing

• Do analogies help in resolving evolutionary relationships?

Determining Character States

• It is critical to determine which character states are ancestral and which derived

– Can use outgroups or closely related lineages; often use sister group – the most closely related

lineage

– Character states shared with outgroup likely are ancestral

 

Types of groups on cladograms

• Monoplyletic

– includes hypothetical ancestor and all descendents

• Paraphyletic

– does not include all descendants of an ancestor

• Polyphyletic

– Collection of descendants from >1 ancestor not including all ancestors

Types of characters

• Behavioral

• Physiological

• Mophological

• Molecular

 

Molecular vs Morphological Characters

• Molecular

– Huge number of possible characters (down to each nucleotide)

– Can find parts of genome not under environmental selection

– Long time periods can obscure due to saturation (problems with parallel evolution)

– Time to saturation depends on rate of evolution at each locus

• Morphological

– Evolve more slowly (little saturation)

– Can include extinct taxa

– Can have problems with convergence

– Defining characters can be difficult

• Use of both types of data best!

 

Fossil Taxa

• Contribute most when they help plug holes in long divergent lineages

• Can complete morphological series, help determine homologies

• Can help determine earliest occurences

• Can’t Use many characters – results in poloytomy (unresolved nodes)

Constructing a Cladogram

• Select group, define all taxa

• Select and define characters and character states

• Create data matrix

• Use outgroup comparison to determine ancestral and derived states

• Construct all possible cladograms

• Select best cladogram using parsimony

• Principle of Parsimony – the best cladogram is the one involving the fewest evolutionary transitions

(steps)

 

Uses of phylogenies

• Character mapping

Pinniped Evolution and Systematics

The pinnipeds

• Monophyletic group with 3 monphyletic families

• 18 phocids, 14 otariids, walrus

• Diversity was once much greater (13 species of walrus are extinct)

• First pinnipeds arose in Oligocene (27-25mya)

• Much speciation in last 2-5 million years

• Poor fossil record generally

Major pinniped synapomorphies

• Large infraorbital foramen (hole below eye to allow vessel and nerve passage) (1)

• Short, robust humerous (6)

• Digit I on hand emphasized (7)

• Digit I and V on foot emphasized (8)

 

Mono or diphyly?

• Evidence for diphyly

– Biogeorgaphy and morphology

– Otarrids (eared seals)  and odobenids (walrus)close to bears; phocids (earless seals)  close to mustelids (otters, weasels)

• Evidence for monophyly: the best explanation

– Molecular, karyological, morphology

– All support close ties to ursids (bear), mustelids, otters (sister group unclear)

– Diving behavior and breeding patterns suggest eared seals evolved first (Costa 1993)

• Phocids are most aquatically adapted (diving, breeding, body plan)

Early Pinnipeds

– Find describe in 2009 sheds new light on early evolution

 

– Pujila darmwini was “walking seal” ~24 mya

– Otter-like body, webbed feet, lived in freshwater lakes of Canadian Arctic

– Suggests pinnipeds went through a freshwater phase

– High productivity associated with cold water upwelling probably supported prey base early pinnipeds

exploited

– First found from cool waters and rocky coasts of eastern N. Pacific during late Oligocene

– Pinnipedimorpha clade

– Show ancestral, heterodont (having teeth of different shapes, such as the molars and incisors of humans), dentition

– Many similarities to archaic bears

– Later forms show derived homodont dentition

Early Pinnipeds

 

 

 

 

•         • Pinnipedimorpha clade

•         – Lateral and vertical movement of vertebral column possible

•         – Both sets of flippers modified for aquatic locomotion

•         – Still very capable on land, probably spent more time there than modern forms

•         Modern Pinnipeds: Otariidae

 

•         • Seal lions and fur seals

•         • Shallow divers often targeting fast-swimming fish

•         • Monophyletic group first appeared late Miocene (11 mya) but all modern forms in last 2-3 my

•         • Two subfamilies

•         – Otariinae (seal lions)

•     – Arctocephalinae (fur seals)

 

•       In cladistics, a synapomorphy or synapomorphic character is a trait that is shared ("symmorphy") by two or more taxa and their most recent common ancestor, whose own ancestor in turn does not possess the trait.

 

 

•         Some Otariid synapomorphies

•         – Frontals extend anterior between nasals (9)

•         – Uniformly spaced pelage units (primary and secondary hair)

•         – Trachea subdivides close to voicebox (13)

•         – Secondary spine on scapula (11)

•         – External ear flaps “pinnae”

•         – Can turn hindflippers forward; use to walk

•         Otariid systematics

•         – Otariinae (sea lions) monophyletic (single stock) , not Arctocephalinae (fur seals) which are still poorly resolved

•         – Hybridization and Introgression may cause problems

•         – aggressive sexual behavior of male sea lions directed at other species

 

•         Modern Pinnipeds: Odobenidae

•         • Current 2 subspecies relicts of once diverse group

•         – Modern walrus large-bodied, shallow diving mollusk feeder

•         • Monophyletic family, origin middle Miocene (16-9 mya) eastern North Pacific

•         Odobenid synapomorphies

•         • Five synapomorphies

•         • Modern walrus distinguished by squirt-suction feeding

•         • TUSKS ARE NOT A SYNAPOMORPHY

•         – They evolved in only one lineage leading to modern walrus

•         – Many ancient odobenids did not have tusks

•         Where do the odobenids fit?

•         • Molecular evidence points to otariids, but morphological data suggests a close association with phocids

 

•         – Middle earbone enlarged

•         – No pinnae

•         – Well-developed thick subcutaneous fat

•         – Abdominal testes

•         – Similarities in hair and venous system

•         • What gives?

•         – Still unclear where walrus fit in pinniped clade

•         – Odobenids probably branched off from basal pinnipeds very early leading to a long branch

•         – Subsequent long-branch attraction causes molecular similarities

•         Odobenid movements

•         • Origin in eastern North Pacific

•         • Invaded Atlantic through Carribean

•         • 600,000 ya modern walrus reinvades Pacific through Arctic and diverge into subspecies

 

 

•         – Middle earbone enlarged

•         – No pinnae

•         – Well-developed thick subcutaneous fat

•         – Abdominal testes

•         – Similarities in hair and venous system

•         • What gives?

•         – Still unclear where walrus fit in pinniped clade

•         –Modern Pinnipeds: Phocidae

•         – “True” seals, lack ear flaps

•         – Generally larger than otariids

•         – Some fantastic divers

•         – Weddell and elephant seals over 1000m

•         – Late Oligocene origin (29-23mya) in N. Atlantic

•         – Monphyletic family with two subgroups

 

•         – monoachines and phocines

•         Some phocid synapomorphies

•         • Unable to turn hindflippers forward

•         • Inflated entotympanic bone (21)

•         • No supraorbital process (10)

•         Subspecies, hybridization and a misplaced genus

•         – Five subspecies of harbor seal recognized based on morphological, molecular, behavioral differences

•         – Eastern and western sides of Atlantic and Pacific, lakes of northern Quebec

•         – Harp seal Phagophilus groenlandicus x hooded seal Cystophora cristanta hybird – what does this mean

•         for biological species concept

•         – What is the status of the gray seal genus?

 

•         Phocid systematics

•         • Are traditional subgroups monophyletic?

•         • Monk seals Monachus often considered most basal of phocids due to ancestral characters (some moreso

•         than fossil taxa)

•         Pinniped Evolution: Summary

•         • Morphologic and molecular data support monophyly

•         • Derived from arctoid carnivores, probably close relatives of bears

•         • Earliest appear 27-25mya in north Pacific

•         • Modern lineages diverged quickly

•         • Position of the walrus unclear

 

•         Cetacean Evolution and Systematics

•         Cetaceans

•         • Monophyletic group with 3 suborders

•         – Archaeoceti (extinct)

•         – Odontoceti (~76 species)

•         – Mysticeti (11 species)

•         • Earliest marine mammals (with sireneans) 53-54 mya

•         Cetacean Origins

•         • Currently some questions about origins: several competing hypotheses

•         • Evolved from small primitive ungulate group

•         – Could share common ancestor with hippos

•         – Could be sister group of other artiodactyls (even-toed; hippos, camels, antelope, pigs, giraffes, etc)

Archaeoceti (extinct)

 

 

•         – Could be another ancestor not closely related to moder artiodactyls

•         Cetacean Origins: The old favorite

•         • 1. Decendent of Order Condylartha, Family Mesonychidae

•         • Wolf-like with digitigrade stance (walk on toes), possibly hoofed

•         • Massive crushing dentition; early skulls suggest similarity

•         Cetacean Origins: close to hippos?

•         • 2. Some molecular data points to close affinity with hippos; recent skull finds disagree – more like

•         mesonychids

•         Cetacean Origins

•         3. Sister group to clade including hippos and artiodatyls; not particularly close to mesonychids

•         –

 

 

•         – Probably all derived from mouse-deer like ancestor

•         Cetacean Origins: Indohyus  brings us closer to an answer

•         • 4. Sister group to cetaceans more primitive than other artiodactlys

•         – Recent finds in India suggest cetaceans closest ancestor is an ancient artiodactyl group (raoellids)

•         – Similarity to cetaceans based on morphology of inner ear, the arrangement of incisors, and

•         morphology of premolars

 

•         – Indohyus was an aquatic wader based on bone density and oxygen isotopes

•         – Carbon isotopes suggest feeding on terrestrial vegetation or omnivores on land but escaped to water

when in danger like modern African mouse deer

•         – Adaptation to aquatic habitats did not occur first in early cetaceans, but more basal species –

 

•         cetacean branch probably driven by switching to aquatic prey (unique dentition and oral skeleton)

•         – Early cetacean ancestors went through a hippo-like stage

•         – Study published in 2009 suggests that hippos are, in fact, closest living relatives of cetaceans.

•         Archaeocete cetaceans

•         • Paraphyletic group of ancient whales that gave rise to modern whales

•         – lack telescoped bones of the skull

•         – Elongate snout

•         – Narrow braincase

•         – Large temporal fossa

•         – Well defined sagital and lambdoidal crests

•         • Earliest from Early Eocene (>50 mya)

•         • Extinct by end of Eocene

 

•         • Pakecetoids are most ancient group (50 my)

•         – Pakecetus – earliest whale; India and Pakistan

•         – Ear morphology gives them away as cetaceans

•         – Lived in an arid environment with ephemeral streams and floodplains

•         • Always found in river deposits

•         • At best site, 60% of mammal remains are pakicetids!

 

•         •– Quadropedal and probably mainly terrestrial but not swift runners (dense bones that may have

•         been for ballast)

•         – Long thin legs and short hands and feet suggest they were poor swimmers (quadropedal

•         paddling) and many deposits were rivers that were too shallow for swimming

•         – Teeth vary greatly – some hyena-like

•         • may have been scavengers or predators

 

•         • Probably ate freshwater aquatic organisms and land animals near water

•         • Ambulocetids

•         – Found in middle Eocene rocks of India and Pakistan

•         – Most basal amphibious marine cetaceans

•         • Nearshore marine (estuaries and bays) but tied to freshwater for drinking

•         – Abulocetus natans and others close to size of male sea lion

 

•         – Show first signs of hearing adaptations

•         – Eyes above profile of skull

•         • Ambulocetids

•         – Likely slow on land

•         – Elongated hind feet and tail that would aid in locomotion

•         • Probably swam like modern otter swinging tail and feet

•         – Probably ambush hunter like modern crocodiles

 

•         • Remingtonocetidae

•         – Short-lived group from Middle Eocene of India and Pakistan

•         – Nearshore tidal environments, but more aquatic than ambulocetids

•         – Long narrow jaws

•         – Probably swam with tail like Amazonian giant otter

•         – Captured fast-swimming aquatic prey

 

•         •– Protocetids

•         – Globally distributed during the middle Eocene

•         • First group to leave South Asia

•         – Expanding niches inhabited including deep offshore waters but probably restricted to tropics

•         – Nasal openings more caudal than earlier species

•         • Could breath with much of head underwater

•         – No fluke

 

•         •– Lifestyle probably very similar to modern pinnipeds

•         – Hindlimbs may not have been able to support weight in some species

•         • Basilosaurids

•         – Middle to late Eocene/early Oligocene

•         – large-bodied family with elongated vertebral bodies (Basilosaurinae)

•         – Very reduced hind limbs – fully aquatic

•         – Basilosaurus grew to 25m

•         – Throughout the tropics and subtropics

•         – Had fluke, but back undulations rather than the fluke provided propulsion

•         – Piscivorous

•         • Dorudontids

 

•         •– Lifestyle probably very similar to modern pinnipeds

•         – Hindlimbs may not have been able to support weight in some species

•         • Basilosaurids

•         – Middle to late Eocene/early Oligocene

•         – large-bodied family with elongated vertebral bodies (Basilosaurinae)

•         – Very reduced hind limbs – fully aquatic

•         – Basilosaurus grew to 25m

•         – Throughout the tropics and subtropics

•         – Had fluke, but back undulations

rather than the fluke provided

 propulsion

 

•         Archaeocete trends

•         – Rapid evolution (few million years) from

•         – Quadropedal to flukes (hindlimb reduction)

•         – Freshwater dringing to seawater drinking

•         – Land animal to not able to move on land and giving birth in water

•         – Movement of nostrils to the top of the head

•         – Extinction probably tied to changes in food supply driven by oceanographic change

 

•         Modern Cetaceans

•         – Diverged from Archaeocetes about 37 mya

•         – Monophyletic clade derived from dorudontids

•         – Split between mysticetes and odontocetes probably 35 mya

•         – Synapomorphies

•         – Telescoping of skull: movement of blowholes to the top of skull

•         • Migration of premaxillary and maxillary bones forms a rostrum (beak)

•         – Fixed elbow joint not present in archaeocetes

•         Mysticetes (Baleen whales)

•         – Modern forms distinguished by baleen plates, but early mysticetes had teeth

•         – Origin probably tied to Oligocene development of Circum-Antarctic current and generation of nutrientrich

 

•         upwelling that led to huge zooplankton shoals

•         – Early mysticetes were small 4-5 m

•         – Major evolutionary transition is from raptorial predation (single prey item at a time) with teeth to batch

•         or filter feeding with no teeth (baleen present by Oligocene, but decomposes so record poor)

•         – Other trends include increased body and head size, shortening of the neck

•         Mysticete Synapomorphies

•         • Maxilla extends posteriorly to form infraorbital process

•         • Mandibular symphysis (lower jaw connection) unfused

 

•         Modern Mysticete Relationships

•         – Four extant families?

•         – Balaenopteridae,

•         – Balaenidae

•         – Eschrichtiidae

•         – Neobalaenidae

•         – Taxonomy not well-resolved

•         Mysticetes: in order of divergence

•         – Balaenidae

•         – Right whales and Bowhead

•         – First appear in early Miocene (23 mya)

•         – Heavy body, cavernous mouth, no throat grooves

•         – Head 1/3 of length

•         – Long baleen plates

 

•         – Only mysticetes with 5 digits on forelimb

•         – Monopyletic

•         • Support for two separate genera poor

•         – Neoalaenidae

•         – Anatomical data places as separate family outside Balaenidae

•         – More anteriorally thrust occipital shield

•         – Shorter, wider mouth for shorter baleen

•         – Separate from balaenids due to presence of dorsal fin, throat furrows, different type of baleen,

•         relatively smaller heard, four digits on hand, shorter humerous)

 

 

•         – Eschrichtiidae-grey

•         – Current species has 100,000 year fossil record (only one for family)

•         – North Atlantic population extinct in 17th or 18th century

•         • No dorsal fin

•         • 2-4 throat grooves

•         • Baleen is thicker, fewer in # and whiter than rorquals

 

 

•         – Balaenopteridae

•         – Fossil record extends 10-12 mya from Americas, Europe, Asia, Australia

•         – Hybrids occur

•         – Dorsal fin

•         – 14-22 (humpback) to 56-100 (fin) throat grooves extend beyond gular (cooling)region

 

•         – Short baleen

•         Odontocetes

•         • Diverse array of toothed forms from freshwater rivers to deep-diving in pelagic habitats

•         • First appear in fossil record 28-29 mya

•         • Major Miocene radiation of pelagic forms appears to be linked to changes in currents and thermal

•         gradients

•         • Monophyly well supported despite well-publicized argument against with early genetic data

•         Are odontocetes monophyletic?

•         • Most morphological characters argue that they are, but one of the supposed synapomorphies has come

•         been disputed: presence of a single blowhole

•         – Odontocete facial structure serves a number of functions

•         – Respiration cause of much skull rearrangement

 

•         – Sound production (echolocation) and detection another major force

•         – Buoyancy control, at least in sperm whales

•         – Some of the 20 Synapomorphies

•         – Concave facial plane

•         – Asymmetric cranial vertex

•         – Premaxillary foramen present

•         – Maxilla overlays supraorbital process (frontal bone)

•         – Antorbital notch present

•         – Asymmetric skulls (except possibly most primitive)

•         – Asymmetric soft tissues in modern forms due to enlargement on right side

•         – Fatty melon in front of nasal passages for echolocation

 

•         Ziphiidae

•         • More than 20 species in 5-6 genera extant

•         – Found in Mocene and Pliocene, including one freshwater form; extant species mainly pelagic

•         – Trend towards loss of teeth with exception of 1-2 pairs anteriorly which become enlarged (only

•         Shepard’s beaked whale has full functional dentition)

•         • Possible sexual display/weapons

•         – Pair of throat grooves that converge anteriorly

•         – Phylogeny unclear; no rigorous cladistic review

•         Physeteridae

•         • Long fossil record (29-21 mya), once diverse but only one extant species

•         • Loss of one or both nasal bones

•         • Deepest known divers

•         • Have spermaceti organ

 

•         – in supracranial basin

•         – may occupy 30% of length and

•          20% of weight

•         – May control buoyancy but still unclear

•         Kogiidae

•         • Linked into a superfamily with sperm whales because of supercranial basin and spermaceti organ

•         • Lack both nasal bones

•         • Have short rostrum and are much smaller than sperm whales (<4m; <2.7m)

•         • Oldest known from late Miocene (8.8 mya)

•         “River Dolphins”

•         • Once put into a single family, but similarities (reduced eyes, elongated snouts) are due to convergent

evolution

 

•         – freshwater/estuaries have

•          been invaded at least 4 times

•         Platanistidae

•         • Asiatic river dolphins

•         – Ganges and Indus Rivers

•         – Reduced eyes in Ganges form

•         – Long narrow beak with numerous narrow pointed teeth

•         – Broad paddle-like flippers

•         – No known fossil record, time

•         of freshwater invasion unknown

•         – Bony facial crest

•         Pontoporiidae  • Fransiscana

•         – Coastal waters of western S. Atlantic

•         – Long rostra, tiny teeth – Close relative of Iniidae

 

•         Iniidae

•         • Amazon river (botu)

•         – Reduced eyes

•         – Extremely elongated rostrum and mandible

•         – Conical front teeth, molariform rear teeth

•         – Greatly reduced orbital region

•         – Maxilla forms crest

•         – Fossils from late Miocene originated in Amazonian basin

•         Lipotidae

•         • Yangtze Tiver (baiji)

•         – Narrow, upturned beak

•         – Triangular dorsal fin

•         – Broad round flippers

•         – Reduced eyes

•         – One fossil, one extant species from China

 

Delphinidae

•         – Most diverse cetacean family 36 sp, 17 gen

•         – Open ocean to some into freshwater (Orcella brevirostris, Sotalia fluvatilis)

•         – Most small to medium 1.5-4.5m, killer whale to 9.5m

•         – Loss of posterior sac of nasal passage

•         – Reduction of posterior end of left premaxilla: does not contact the nasal

•         – Oldest from late Miocene (11 Ma)

•         • Systematics are still a mess

•         – Some genera are not monophyletic

•         – Diversity likely to increase (e.g. Tursiops)

•         – Stenella is polyphyletic

•         Phocenidae

 

•         – Six small extant species

•         – Synapomorphies

•         – Raised rounded protuberances on premaxillae

•         – Premaxillae do not extend beyond anterior half of nares

•         – Spatualte (not conical) teeth

•         – Sister taxa of delphinids

•         – First appeared in late Miocene, eastern Pacific

•         Monodontidae

•         • Delphinoids with flat or convex facial planes in profile

•         • Extant species in Arcitc

•         • Miocene/Pliocene some species found in E. Pacific to Baja California

 

•         Sirenians, Sea otters, Polar Bears, and other marine mammals: Evolution

•         Sirenians

•         • Monophyletic group with two extant familes

•         – Trichechidae (manatees)

•         – Dugongidae (dugongs)

•         • Unique in strictly herbivorous diet

•         • First appear in early Eocene (50 mya)

•         Sirenian Origins

•         – Monophyly strongly supported

•         – Syapomorphies

•         – External nares retracted and enlarged reaching beyond the level of the anterior margin of the orbit

•         – Premaxilla contacts frontal

•         – Lacks sagital crest

•         – Bones dense and compact (for buoyancy regulation)

•         – Closest living relatives are proboscideans (elephants)

•         – Teeth and skull morphology unite the groups

•         – Extinct Desmostylians form clade with sirenians and elephants (monophyletic “Tethytheria”)

•         – First arose in Old World, but quickly spread to New World 50 mya

•         Ancient Sirenians

•         • Prorastomus (50mya) first (Jamaica)

•         – Had functional hindlimbs

•         – Dense bones, swollen ribs and presence in marine deposits suggest partially aquatic; riverine and

•         estuarine selective browser

 

•         • Protosiren (middle Eocene) (Egypt)

•         – Functional terrestrial locomotion but auditory, olfactory, and visual systems appear modified for

•         aquatic lifestyles

•         • Much of the spread of sirenians tied to the spread of seagrasses in the temperate Pacific

•         Modern Sirenians: Trichechidae

•         – Appear to be derived in late Eocene/early Oligocene, possibly from dugongids

•         – Monophyletic, united by features of the skull and reduction of neural spines on vertebrae

•         – Mainly freshwater/estuarine

•         – Ability to produce new teeth as old ones are worn down

 

•         • 3 modern species

•         – West Indian manatee (Trichechus manatus)

•         • 2 subspecies: Antillean (T.m. manatus); Florida (T.m. latirostris)

•         – Amazon manatee (Trichechus inunguis); freshwater only

•         – West African manatee (Trichechus senegalensus)

•         Modern Sirenians: Dugongidae

•         • Paraphyletic family with Caribbean/W. Atlantic origins spreading to Pacific

•         • More marine than manatees

•         • Two extinct subfamilies and one extant

•         – Hydrodamalinae (includes Steller’s sea cow) appears to have split from Dugonginae (dugong) in

•         late Eocene

•         • Includes Stellar’s sea cow (extant into historical times)

 

•         • Some temperate species

•         • Large body size

•         • Loss of tusks

•         • May have fed on kelp high in the water column

•         Steller’s sea cow

•         • Named after Georg Steller

•         • 7.6m long, 4-10 tons

•         • Lacked teeth, had bark-like skin

•         • Cold waters near islands of the Bering Sea

•         – Prehistorically from Japan to Baja California (to Montery 19,000 years ago)

•         • Extinct by 1768 (27 years after discovery)

•         – Mainly Russian hunting, but possibly exacerbated by aboriginal hunting

 

•         Dugonginae

•         • Currently one species, but once many genera

•         • Tropical and subtropical

•         • Once widespread; 15 mya from North and South America, Caribbean, Mediterranean, Indian Ocean,

•         North Pacific

•         • Some extinct species used tusks to dig up seagrasses

•         • Modern dugongs use tusks socially, not for feeding

•         Sirenian evolution in the Caribbean (Domning 2001)

•         • From Oligocene onwards, there was a great diversity of sirenians in the Caribbean, especially dugongids

•         • Seagrass communities were similar to extant ones but were more diverse

•         • Habitat could be partitioned along several axes

•         – Rhizome size

 

•         – Location of feeding in water column

•         • Morphology of sirenians reflects partitioning of seagrass resources

•         – Body size differences lead to differences in access to shallow waters and ability to consume more

•         fibrous seagrasses (bigger are better)

•         – Rostral deflection influences ability to feed on the bottom or on midwater or surface plants and

•         ability to dig

•         – Tusk size influences ability to dig out largest rhizomes

•         – Interaction of tusk size and defection can be complex

•         • Why so few species today?

•         • Close of Central American Seaway about 3 mya led to major shifts in habitats

 

•         – Dugongids died out along with large rhizome seagrasses

•         – Manatees were able to disperse into open marine habitats to move into North America and to West

•         Africa

•         Desmostylia: Sirenian Relatives

•         • Only extinct Order of marine mammals

•         • Confined to North Pacific (Japan through N. America)

•         • Late Oligocene to Middle Miocene (33-10mya)

•         • Hippo-like amphibious quadropeds

•         • More closely related to elephants than sirenians

•         • Probably fed on algae and seagrasses in subtropical and cool-temperate waters

•         • Locomotion probably like polar bears

 

•         –Thalassocnus

•         • Aquatic ground sloth!

•         • Pliocene marine rocks of Peru

•         • Medium to giant sized herbivores

•         • Aquatic or semi-aquatic grazer on seagrasses or seaweeds (well developed lip for grazing)

•         • Probably swam with tail

•         Kolponomos

•         • Bear-like carnivore (early Miocene)

•         • Massive skull, down-turned snout, broad crushing teeth

•         • Coastal habitat feeding on marine invertebrates on rocks and crushed their shells

 

 

•         • Sea otter only marine mammal that may be similar in habitat

•         • Relationships problematic

•         – Appears to be closely related to basal ursids and forms leading to pinnipedimorphs

•         Sea otter Enhydra lutris

•         • Smallest marine mammal but largest mustelids

•         • Three subspecies across northern Pacific

•         • E. lutris arose in North Pacific early Pleistocene (1-3mya)

•         • Several extinct species from Africa, Europe, and Eastern United States that appear to have

•         consumed extremely hard prey items like modern otters

 

•         Polar Bear Ursus maritimus

•         • Most recently derived marine mammals

•         • Descended from lineage of brown bears during middle Pleistocene (300,000-400,000 ya)

•         • Brown bears of southeast Alaskan islands closest relatives

 

 

•       This phylogenetic tree for the sea otter contains all the sea otter genera.  The sea otter is the only member of the genus Enhydra.  Each genus is a monophyletic group, meaning that the organisms in each genus share a common ancestor.  The sea otter is sister to the speckle-throated otter (Hydrictis maculicollis) and is by far the closest relative to the sea otter.  This also shows that the sea otter shares a common ancestor with the Eurasian otter (Lutra Lutra), African clawless otter (Aonyx capensis), small-clawed otter (Aonyx cinerea), and the speckle-throated otter (Hydrictis maculicollis).

 

MARINE MAMMAL DISTRIBUTION

Zoogeography

 

 

Zoogeography

• Study of the distribution of extant species

• Water temperature critical for marine mammals

– Directly on animals physiology

– Indirectly on prey

– Species often occur in latitudinal bands

• Shape of nearby land/shelf

• History is Critical

– When did lineages arise and diversify?

– Continental Drift and Climate Change

 

– The early and middle

 Miocene

Basic Climatic Zones

• Polar

• Subpolar/Cold Temperate

• Temperate

• Subtropical

• Tropical

Basic Types of Distribution

• Cosmopolitan- a taxon is said to have

 a cosmopolitan distribution if its range extends across all or most of the world in appropriate habitats. For instance, the killer whale has a cosmopolitan distribution, extending over most of the world's oceans.

• unknown for many species

 

–• Pan Tropical In biogeography, a pantropical ("across the tropics") distribution is one which covers tropical regions of all of the major continents, i.e. in Africa, in Asia and in the Americas

• Temperate/Subpolar

• Circumpolar

• Anti-tropical

• Regional (Endemic)

• still unknown for many species

 

Horizontal Habitats

• Nearshore

– Lakes and Rivers

– Estuaries

– Freshwater and saltwater mix, high productivity and low visibility

– Bays

– Relatively protected waters

– Coastal

– Shallow waters, often high energy (wave action)

• Offshore

– Continental Shelf

• Relatively shallow but deeper than nearshore habitats

• Light usually penetrates to bottom over much of this habitat

 

– Continental Slope

• Depth changes rapidly, light penetration begins to diminish

• Often associated with high productivity

– Pelagic

• Extremely deep, no light at depth

• Generally low productivity except in areas of relief (seamounts, etc)

• Frontal dynamics and current features may be very important

Vertical Marine Habitats

• Vertical Distribution of Habitats

– Light, temperature, pressure, salinity, and water density change considerably as depth increases

– Deep-water habitats can be divided into photic and aphotic zones

 

– Depth where these start varies considerably with water visibility

Ice Habitats

• Many pinnipeds rely on ice as habitat

– Haul outs

– Breeding

• Polar bears use the ice to stalk seals

• Cetaceans must navigate the ice to access many polar habitats

– Fast ice

– Ice attached to shore that does not move

– Pack ice

– Ice that forms at sea and moves with currents

– Covers central Arctic, surrounds Antarctica

– Largely melts in summer, especially in Antarctica

 

– Ice floes

– Large pieces of sea ice broken by wind or waves

– Leads

– Open water formed when floes move apart

Current Distributions: Mysticetes

• Typified by seasonal shifts from high latitudes (feeding in summer) to low latitudes (breeding in winter)

• Bowhead: arctic

• Right whales: temperate

• Gray whale: warm temperate

• Rorquals: cosmopolitan

– B. edeni, B. brydei pantropical (<40°)

Current Distributions: Odontocetes

• Not limited by temperature in general

• Sperm whales – pelagic, cosmopolitan

 

– 2 smaller species more tropical

• Narwhal and Beluga – coastal, arctic

– Move with sea ice

• Beaked whales – pelagic, regional or antitropical

– In general, very poorly known

• Delphinidae – coastal and pelagic forms; tropical, anti-tropical, cosmopolitan, regional all found

• Porpoises – coastal, sometimes freshwater, regional/endemic

• “River Dolphins” – large tropical river drainages; one coastal species in SA

– Indus, Ganges, Yangtze, Orinoco, Amazon

Current Distributions: Sirenians

• Tropical/Subtropical; Regional

– Recently extinct Stellar’s Sea Cow was cold temperate

 

• Dugongs: fully marine

– Limited by marine plant distributions

– Prefer >18°C, <6m depth

• Manatees (Trichechids): tend towards freshwater sources

– Amazon manatee: obligate fresh water

Current Distributions: Pinnipeds

• Cetaceans more successful in low latitudes, pinnipeds more successful at high latitudes

• Odobenids

– disjunct circumpolar

• Otariids

– cool temperate/subpolar (except N. Atlantic)

– lower latitudes where cold currents occur

 

•– Arctopcephalus (fur seals) have 6 species only in southern ocean

– Distributions highly influenced by sealing

– Some species highly endemic, but others widespread

– Zalophus (sea lions) mainly in north with California sea lion most widespread

• Phocids

– Most widespread pinnipeds

– Northern group Phocinae

• Many give birth on ice or in ice lairs

• Temperate, Arctic, subarctic, some landlocked lake seals

 

– Monachinae

• Warm water seals, elephant seals, Antarctic ice seals

– Some ice seals can maintain holes (Ringed seal) in ice, others must stay near ice edge (Bearded seal)

– Monk seals only true warm water seals

Current Distributions: Sea otters and Polar Bear

• Sea Otter

– North Pacific

– Tied to shallow waters

– Poor dispersal ability

• Polar Bear

– Circumpolar

– Track seal distribution (mainly ringed seals)

 

Current and historical distributions

• May have been modified greatly by human activities both ancient and modern

• Pinnipeds in central and northern California are a perfect example

Pinnipeds of central California

• Currently dominated by CA sea lions and N elephant seals with northern fur seals (NFS) rare and only

breeding in recent and small colonies on offshore islands

• Most NFS breeding is in Alaska and may forage in pelagic waters as far south as Baja

• A strange observation: remains of NFS extremely common in archeological sites in California.

Explanations of NFS abundance in ancient times

• Always had northern rookeries and foraged closer to shore where they were available or were hunted

 

more commonly

• More abundant on offshore rookeries of California

• Were historically more abundant and had mainland rookeries

Burton et al (2001)

• Used archeological data, stable isotopes to address these hypotheses: what did they find?

– Differences in hunting or foraging location did not explain remains

– NFS were mainland breeders in CA during mid-late Holocene

– NFS were extremely abundant historically compared to other pinnipeds and may have limited the

abundance of other pinnipeds

 

 

Range of Polar bears

•       Philos Trans R Soc Lond B Biol Sci. 1999 January 29; 354(1380): 193–201.

•       doi:  10.1098/rstb.1999.0371

•       PMCID: PMC1692474

•       The evolution of cost efficient swimming in marine mammals: limits to energetic optimization

•       T. M. Williams

•         One of the most characteristic features of marine mammals is a streamlined body shape.

•         This is not surprising when one considers the forces that the animal has to overcome in order to move through water.

•         When a swimmer moves through water a force, termed drag, acts backward on it, resisting its forward motion.

•         The equation describing total body drag is given by

•         Total Drag = 1 / 2ρ V²ACd ( 1) where ρ is the density of the fluid, V is the velocity of the fluid relative to the body, A is a characteristic area of the body, and Cd is the drag coefficient (a factor that takes into account the shape of the swimmer).

 

•           The primary mode of locomotion for marine mammals with the possible exception of polar bears ( Ursus maritimus ) is swimming. For dolphins, porpoises and whales, it is the

•           only form of locomotion.

•           The duration of swimming among these mammals may be as short as several seconds when moving between

•           prey patches or as long as several months during seasonal migrations across entire ocean basins.

•           Although swimming by marine mammals often appears effortless, it is in reality a delicate balance between precise body streamlining, exceptional thrust production by specialized propulsive surfaces, and locomotor efficiency

•         The optimum fineness ratio that results in minimum drag with maximum accommodation for volume is 4.5.

•          Calculations of the fineness ratio for a wide variety of marine mammals show that many species have body shapes that conform to the ideal hydrodynamic range

•         A review paper by Fish (1993) showed that many cetaceans, pinnipeds, and sirenians have body shapes with Fineness

•          Ratios that range from 3.0 to 8.0.

•         The species examined included seals, sea ions, and odontocete whales that are considered by many to typify a streamlined body profile.

•         Even mysticete whales with enlarged heads

•         and jaws specialized for filter feeding maintain a streamlined body profile when swimming .

 

•         There are four primary types of drag that contribute

•         to total body drag:

•          (1) skin friction drag which is a tangential force resulting from shear stresses in the water sliding by the body,

•         (2) pressure drag which is a perpendicular force on the body associated

•         with the pressure of the surrounding fluid,

•         (3) wave drag that occurs when a swimmer moves on or near the water surface, and

•         (4) induced drag that is associated with water deflection off hydrofoil surfaces such as fins, flukes, or flippers.

•         Of these, pressure drag is the component most influenced by body streamlining in marine mammals.

•         The more streamlined a body, the lower the pressure drag and consequently the lower the total body drag of the swimmer.

 

•         Mammals whose lifestyles or foraging habits involve prolonged periods of swimming have streamlined body shapes.

•         In contrast to the lanky appearance and appendages of terrestrial mammals, marine mammals tend to have a reduced appendicular skeleton and characteristic tear drop body profile.

•         External features that may disrupt water flow across the body are also reduced or absent in many species of marine mammal.

•         These features include the pinnae (external ears), limbs, and long fur.

•         In highly specialized swimmers such as dolphins the skin contains microscopic ridges that help to direct the flow of water in a controlled manner down the body.

•         All of these adaptations prevent the onset of turbulence in the water surrounding  the swimmer and thereby reduce total body drag.

 

•         Hydrodynamic theory describes the streamlined body shape as one in which a rounded leading edge slowly tapers to the tail, and total length is 3–7 times maximum body diameter.

•         The ratio of these morphological measurements, termed the Fineness ratio

•          Specifically, it is the ratio of the length of a body to its maximum width; shapes that are "short and fat" have a low fineness ratio, those that are "long and skinny" have high fineness ratios.

•          Aircraft that spend time at supersonic speeds generally have high fineness ratios, a canonical example being Concorde.

 

•         However, the loss of this hydrodynamic profile when the animals open their mouths quickly results in a marked increase in drag, a reduction in forward speed, and a concomitant elevation in energetic costs

•         Despite nearly ideal body streamlining, all marine mammals must contend with drag forces when moving through the water.

•         These forces can be a considerable challenge for the swimmer and will influence how quickly the animal will be able to move.

•         It is apparent that the velocity of the swimmer will have a large impact on total body drag.

•         As the swimmer moves faster, body drag increases exponentially.

 

•       Whether the sea otter swims on the water surface or submerged, body drag increases with velocity.

•       However, body position clearly affects the level of total body drag encountered by the sea otter.

•       At all comparable swimming speeds, body drag is higher for the otter moving on the water surface than when it is swimming submerged.

•       The same results have been found for other swimmers, including humans and harbor seals ( Phoca vitulina ).

•       In general, body drag for a swimmer moving on or near the water surface is 4–5 times higher than the level of drag encountered by the submerged swimmer moving  at the same speed

 

•         A hallmark of marine mammal swimming is the use of lift-based propulsion that allows thrust to be generated through the entire stroke cycle.

•         This capability is found in highly adapted marine species such as pinnipeds and cetaceans.

•          It contributes to an increase in locomotor efficiency in marine mammals, especially when compared to the inefficient drag-based swimming styles of humans and terrestrial mammals

•         Marine mammals use a wide variety of swimming styles to move through the water.

•         The most terrestrial species of this group, the polar bear and sea otter, swim by alternate strokes of the

•         forelimbs or hind limbs, respectively.

•         Polar bears use a dog style of forelimb paddling with the hind limbs dragged passively behind or used as an aid to steering.

 

•         Sea otters are unique among marine mammals in their ability to lie on their backs during surface swimming.

•         Propulsion is provided by either the simultaneous or alternate strokes of the hind limbs.

•          When on the surface, sea otters can also swim ventral surface (belly) down using the hind paws for propulsion.

•         The front paws are held against the submerged chest and do not play a role in propulsion during this mode of swimming.

•         Stroke frequency has been measured for swimming sea otters and ranges from approximately 30 to 80 strokes per minute while swimming on the water surface

•         Polar bears and sea otters are the only marine mammals that rely primarily on drag-based modes of swimming.

 

•         These modes of swimming have two distinct phases during the stroke cycle, a power phase when thrust is produced, and a recovery phase when the foot or paw is repositioned for the next stroke.

•         During the power phase, the foot is moved backward relative to the body.

•         Drag created by this motion is subsequently translated into thrust and the animal moves forward through the water.

•         The enlarged hind flippers of sea otters and fore paws of polar bears enable the animals to increase propulsive efficiency by moving a large mass of water during this power phase.

•          The recovery phase of the stroke is only used to bring the limb back to its starting position, and occurs without the generation of thrust.

 

•         Because thrust is produced only during part of the stroke cycle, drag-based modes of swimming are comparatively inefficient.

•         When sea otters want to move quickly through the water, they switch to an undulatory  (wave-like movement patterns ) mode of swimming involving dorsoventral body flexion and simultaneous movements of paired hind flippers.

•         The tail and hind flippers are held straight back and trail the undulatory movements of the trunk.

•         Stroke frequency of sea otters remains relatively constant at 55 strokes per minute during submerged undulatory swimming, which suggests that underwater speed is elevated by increasing stroke amplitude.

•         As observed for submerged swimming sea otters, dolphins and whales use undulatory modes of propulsion.

 

•         The primary propulsive movements of all cetaceans occur in the vertical plane with the posterior third of the body undulating in a dorsoventral direction.

•         “ Semi-lunate ” refers to the crescent shape of the flukes.

•         This mode of propulsion is shared by other fast swimming vertebrates including tuna.

•         ” Undulatory propulsion in cetaceans is considered highly efficient and can generate high levels of thrust on both the upstroke and downstroke.

•         There is no recovery phase and propulsion can be

•         produced throughout the stroke cycle.

•         Stroke frequency using this mode of swimming varies with the speed and size of the cetacean.

 

•         The range of stroke frequencies for bottlenose dolphins ( Tursiops spp.) swimming in a pool is 60–180 strokes.min _ 1 .

•         Stroke frequency decreases with increasing body size among the cetaceans.

•         Thus, we find that the largest species of swimming mammal, the 100 ton blue whale ( Balaenoptera musculus ), uses stroke frequencies that are only one-tenth of the range observed for bottlenose dolphins.

•          A measurement of the stroke frequency of blue whales ascending during a dive was 6–10 strokes.min.

•         Swimming by pinnipeds differs markedly between the eared seals, the otariids, and the true seals, the phocids.

•          Otariids use pectoral appendages to generate propulsive forces during swimming, with the hind flippers trailing passively or occasionally used for steering

 

•         IV. Energetics Fineness Ratio=maximum body length/maximum body diameter

•         The energetic cost of swimming has been measured for numerous species of semi-aquatic and marine mammals using a wide variety of techniques.

•         Smaller swimmers such as sea otters, seals, and sea lions have been studied while they swam against a current in water flumes.

•         Similar to placing a human on a treadmill, flume studies have enabled scientists to measure how much energy a swimmer expends while moving at different speeds.

•         Often oxygen consumption is measured during these tests by using a face mask or metabolic hood connected to an oxygen gas analyzer.

 

•         By training animals to breathe into a metabolic hood, expired respiratory gases can be collected and analyzed for oxygen content.

•         For larger, more powerful swimmers like dolphins and whales, most flumes are not adequate in terms of size or challenging water speeds.

•         Instead, investigators have relied on a variety of novel techniques for determining the energetic cost of swimming in cetaceans.

•         Techniques have included using trained dolphins that match their swimming speed to that of a moving boat in open water or having whales swim to metabolic stations where expired gases can be collected for analysis

•         To compare swimmers of different size, it is useful to convert the metabolic measurements into a cost of transport.

 

•         Defined as the amount of fuel it takes to transport one unit of body weight over a unit distance, the cost of transport is analogous to the fuel rating of an automobile.

•         In this case, the cost of transport indicates the “ gas

•         per mile ” used by the swimmer rather than the “ miles per gas ” achieved by automobiles.

•          The total cost of transport is calculated from the following equation:

•         Total Cost of Transport

•         Oxygen Consumption

•         Swimming Speed  where oxygen consumption is in ml O₂ /kg /sec and speed is in m/sec which results in a cost of transport in mlO₂ /kg /m

 

•         These values are usually converted to an energetic term and expressed as Joules expended per kilogram of body mass per meter traveled .

•         The conversion calculation assumes a caloric equivalent of 4.8 kcal per liter of oxygen consumed and  conversion factor of 4.187 x 10 ³ J per kcal.

•         Comparisons of the cost of transport for a wide variety of mammalian swimmers indicate that swimming is energetically expensive for mammals compared to fish. The total cost of transport for swimming mammals can also be divided into two distinct groups, the semi-aquatic mammals and the marine mammals .

•         Swimming costs for semiaquatic mammals such as minks

•         (Mustela spp.), muskrats ( Ondatra zibethicus ), and humans are 2–5 times higher than observed for marine mammals.

 

•         These high energetic swimming costs are attributed to a wide variety of factors including elevated body drag associated with a surface swimming position and low propulsive efficiency associated with drag based propulsion.

•         Mammals specialized for swimming demonstrate comparatively lower energetic costs.

•         Total cost of transport in relation to body mass for swimming marine mammals ranging in size from a 21 kg California sea lion to a 15,000 kg gray whale ( Eschrichtius robustus ) is described by Total Cost of Transport _ 7.79 mass_0.29 ( 4) where the cost of transport is in J/kg/1/m/1 and body mass is in kilograms.

 

•         Interestingly, the style of swimming used by marine mammals did not affect the cost of transport relationship.

•         Species and swimming styles represented in this equation include sea lions using pectoral fins for propulsion, phocid seals using lateral undulation of paired hind flippers, and odontocete and mysticete whales using dorso-ventral undulation of flukes.

•         The energetic cost of swimming for marine mammals is greater than predicted for salmonid fish of similar body size.

•         Despite specialization of the body and propulsive surfaces for aquatic locomotion, the cost of transport for swimming by seals and sea lions is 2.3–4.0 times higher than predicted for swimming fish.

 

•         Values for cetaceans are somewhat lower, and range from 2.1 to 2.9 times values predicted for fish.

•         Differences in the total cost of transport between marine mammals and fish are due in part to the amount of energy expended for maintenance functions, particularly thermoregulation and the support of a high core body temperature.

•         As endotherms, mammals expend more energy to support the production of endogenous heat than ectothermic fish.

•          In addition, many marine mammals show exceptionally high metabolic rates while resting in water in comparison to terrestrial mammals resting in air.

•          A consequence of these high maintenance costs is an overall increase in the total energy expended during swimming, especially when compared to fish.

 

 

River Dolphins