Marine Mammals

•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.

Marine Mammals

•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

Marine 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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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

Marine Mammals

•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.

•Marine mammals 

•ancestral ties of mammals 

•terrestrial reptiles 

•diverged about 200 mya (225-190 mya) Formation of present Atlantic Ocean

Common mammalian characteristics 

• hair - mammary glands

•few young, lots of care given

•large brain - internal fertilization

•Some on land, some in sea

•viviparous birth- some on land, some in sea

•Endothermic - homeothermy

•breathe air 

derived from terrestrial tetrapod ancestors who drank freshwater

Three separate groups independently gave rise to aquatic descendents  during Eocene (65-50 mya) 

•Order Carnivora polar bear, sea otters 

•Order Pinnipedia seals, sea lions 

•Order Sirenia manatees, dugong 

•Order Cetacea whales, porpoises, dolphins present

Species diverged about 15 mya

convergences

•streamlining of body shape 

•limb modifications flippers,

•disappearance of hind pair in some groups 

•thermal regulation

•large size, thick skin, blubber, fur,

•reduced peripheral circulation,

•higher metabolic rate 

•modified respiratory system

•diving adaptations 

•osmotic adaptations

•impervious skin,

•efficient kidney,

•don’t drink much seawater

•echolocation in some

•distribution more significant ecologic role in polar seas 

•More species Polar and cold temperate 66 sp.

•Tropics and warm temperate 36-41 sp.

•All seas 9 sp.

•Fewer competitors 

•More individuals 

Some species are circumglobal

•Baleen whales, some toothed whales 

•Many species are confined to regions of one ocean seals and sea lions, manatees and dugong, otters, polar bear, walrus

Marine Mammals

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

Marine Mammals

•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.

Order Cetacea Suborder Archaeoceti (Zeuglodontia) All now extinct

intermediate between terrestrial ancestors and present day whales and porpoises

earliest fossils found in freshwater and estuarine environments of the eastern Tethys Sea

Ancestral origins may have been from the Ungulates, either from Artiodactyls (cows, pigs, camels, hippos), Perissodactyls (horses, tapirs, rhinos) , and later, the Mesonychians (freshwater alligator-like mammals)

Appeared in late Eocene (51.4 mya, 54-38 mya) and persisted to Miocene (26-7 mya) Transition from freshwater drinking to seawater drinking in about 2 my Gave birth in tropics, but adults had world-wide distribution heterodont teeth

Suborder Odontoceti Late Oligocene (35 mya 38-26 mya)

Some teeth present during life, single nostril (blowhole)

Asymmetric skull in most sp.

Good vision and hearing produce variety of sounds, clicks and whistles

swallow food whole (mostly fishes and squids)

Usually produce single calves after a 9-15 month gestation

usually nurse for 6 or more months

most species are very social

Ziphiidae beaked whales 18 sp. Delphinidae dolphins 34 sp. Phocaenidae porpoises 6 sp. Platanistidae river dolphins 4 sp. Monodontidae beluga and narwhal Physeteridae sperm whales 3 sp. A 1993 study of mitochondrial DNA places this family with the suborder Mysticeti

Physeter feed on squid at depths down to 1134 m

Remain submerged for up to an hour, though the average is 30 min.

Source of spermaceti (sperm oil)

Source of ambergris

Grow to 38,000 kg (42 tons)

Males maintain harems of 15-20 females

Females remain in tropics, but males migrate to high latitudes in summer

tuna fishing with purse nets inadvertently trap and may kill dolphins and porpoises

Dolphin and porpoise pods are followed by tuna schools because the mammals are better able to locate schools of the fishes they both prey upon

Pods of 50 to several thousand in number (mean is several hundred)

Fishermen use mammal pods to locate tuna

Most commonly caught species are Pacific spotted porpoise (Stenella attenuata)

And spinner porpoise (Stenella longirostris) And occasionally the common dolphin (Delphinus delphis)

Mammal pod is corralled by small fast boats launched from the mother ship

Main vessel then surrounds pod and school of tuna with a purse net ( up to 2000 m long and 200 m deep) which is deep enough to reach into the thermocline

The net is then “pursed” at the bottom and slowly hauled in to concentrate the catch

In 1971, the estimated kill was 310,000 porpoises (3.8/ ton of tuna) ..Since mid 1970s, U.S. fishermen are required to use Medina panel to allow mammals to escape

Suborder Mysticeti late Oligocene (35 mya 38-26 mya)

Baleen or whalebone whales vestigial teeth

adult has baleen in mouth

Horny, elastic, nail-like material derived from skin tissue

filters small sized food from water

two nostrils (blowholes)

skull is symmetrical

Mostly feed on zooplankton (one sp. feeds on benthic amphipods)

Generally mate and give birth in tropics or subtropics during winter and then move to high latitudes to feed during the summer. The northern and southern hemisphere populations are separate.

one (rarely two) calf every 2 years per female after a gestation of 11-12 months

Balaenidae right whales

Very fine filter

consume even copepods

Feed mostly by “skimming”, often in echelon

Prized by whalers

Balaenopteridae

rorquals and humback

Moderately coarse filter, eat mostly euphausiids (krill)

Feed mostly by “gulping”, may use bubble ring to corral prey first

Include largest animal that ever lived, the blue whale ---Up to 30.5 m long, 150 tons [25 ft. long and 2 tons at birth ] Estimated to need 3 million calorie intake/day in summer

3 tons of krill/day

Eschrichtiidae gray whale Coarse filter,

Eat mostly benthic amphipods Extinct in North Atlantic since late 1600s or early 1700s

Now only along Pacific coast of North America

Senses in marine mammals receive information about the environment

Vision varies from poor in river dolphins and manatees to very good in most odontocetes

Small odontocetes with a short snout or pointed beak have binocular vison ..so do right whales

Asymmetric eyeball allows clear vision in both water and air

Taste…little known, but taste buds are present on the tongue of some cetaceans

Touch area of back around blowhole is very sensitive to touch

Touching is common in courting cetacean adults and mothering of young

Rudimentary hairs on chin or rostrum

Sound well developed and common in most (Humans hear 16 to 20000 hz)

Sound velocity in water is some 4.5 times faster than it is in air

purposes: communication, echolocation, stun prey?

Sounds produced and detected Walrus bell-like sound

Otariid seals clicks (northern fur seal), trains of pulses (Weddell seal) Phocid seals musical chirrups and trills (Antarctic phocids), warbles (bearded seal)

Manatees generally silent, but do emit squeaks and chirps

Cows and calves maintain vocal contact Dugong Baleen whales generally produce low frequency sounds and their function is not well known

more sounds when more active, often appear to be contact calls

Rorqual whales 20-200 hz

Usually travel some 80 km, but can travel up to 800 km in the SOFAR or deep ocean channel

Minke and gray whales produce clicks

Humpback whale..40-5000 hz

Songs produced in tropics in winter, usually sung by a single isolated male resting in 20-40 m of water over a smooth bottom

May last 6-35 minutes and be heard 30 km away

Comparable to bird songs (and if speeded up, sound like them)

About 20 syllables or notes grouped in phrases

Groups of similar phrases are called themes

About 6 basic themes in population each year

All males in an ocean basin sing roughly the same song in each year, but all modify the song during the year

Bowhead whales also produce songs, in the Arctic during the spring Odontocetes generally produce a variety of high frequency sounds

Tonal whistles usually used for social messages

Distinctly pulsed clicks used for echolocation50-200 microsec pulse, followed by 50-150 millisec gap, adjusted for particular situation

Also used for communication in sperm and killer whales

Less distinctly pulsed cries, grunts and barks

Signature calls individually unique calls, most are whistles

Delphinidae whistles and squeals 1000-20000 hz

Monodontidae whistles and pulses

Ziphiidae whistles and clicks

Phocaenidae, Platanistidae, and Physteridae produce only clicks

Sound production No vocal cords in cetaceans, so use blowhole area or perhaps muscular pharynx

Small odontocetes usually bounce the sound waves off the front of the scooped out skull behind the bulbous melon

Sound focused by fatty lens shaped melon at boundary of the skin and water

Sperm whale may produce clicks at museau du singe inside skin of front of head (hard, taut internal lips)

Sound reception Seals external auditory meatus and ear drum Cetaceans Inner ear is more isolated from skull by fat and connective tissue

Allows greater limitation of sound reception to a single direction

Sound appears to travel to inner ear along the lower jaw bone, though some say the outer ear passage may be involved in low frequency (But others say this is doubtful)

Echolocation Terrestrial animals bats, shrews, flying lemurs, fat dormouse, golden hamster, oil bird

Marine mammals only definite in odontocetes

A series of clicks Low frequency distant objects--High frequency-close objects

Narrow range of frequencies give more precise image

Duration 40 clicks/sec., 9 pulses/click

Detect squid 400 m away

Feeding

For most marine mammals - whales, dolphins and Dugongs - their entire life is in the water. Life in a marine environment has shaped the biology of these mammals, especially feeding mechanisms. The prey taken ranges from microscopic krill to marine mammals such as seals and even whales.

The large whales - Blue, Sei and Right - filtered feed from the water using baleen plates hanging from the roof of their mouths. They feed on schooling fish and krill, the smallest prey.

Jaw and skull modifications, especially within the whales, dolphins and Dugongs are the most extreme examples of this adaptation to life in the water.

Adaptations include:

· elongated jaws;

· nostril moved to the top of the head; and

· very few or no teeth.

Where teeth are present, they are a conical shaped, designed to grab prey, not chew it. Some groups such as the beaked whales that feed on squid and octopus have, over time lost all functional teeth and now only the males retain a pair of front teeth, for display.

Feeding strategies of the seals resemble those of terrestrial carnivores. They largely feed on fish and possess the full set of teeth needed by a carnivore to catch and kill other vertebrates.

Dugongs are the only true vegetarian marine mammals. Their skull shape and teeth reflect the needs of an animal that only eats seagrasses. The mouth is angled so it is horizontal to the seabed when feeding. The functional teeth remaining are used to grind up the plants.

Reproduction

Reproductive strategies are the most difficult for the animals that are totally marine such as whales, dolphins and the Dugong. For very social animals that live in groups such as dolphins, and the Dugong, finding a mate is no problem. For others, such as loners of the marine mammal world - the large baleen whales - success depends on making sure you are in a certain part of the ocean at the same time each year.

Giving birth to a mammal while underwater presents difficulties. Newborn whales come out tail first to prevent drowning. When the whole body is free, they are gently raised to the surface for their first breath. Most baleen whales wean their young after 6 - 12 months. Some toothed whales continue to feed the offspring for years.

This prolonged nursing means a lower fat content to the milk, around 10 - 30 percent. In whale and dolphin society there is a strong bond between mother and young and amongst some species there is a group responsibility for the care of the young.

Seals return to land on a regular basis to mate and give birth. They congregate in colonies, sometimes in the thousands, and all the pregnant females give birth within days of each other. This situation does have its disadvantages.

Like all crowded areas, the very young are vulnerable. Adult male seals have only one reason for being there, to mate with as many females as possible. Like many mammal species, there is no duty of care by the male of the species for the young.

Migration

In Australian waters true migration - the process of moving by a set route between one habitat and another - is only really carried out by two species, the Humpback Whale Megaptera novaeangliae and the Southern Right Whale Eubalaena australis. Each year populations of both these species make a return journey from the colder feeding grounds of Antarctica to the warmer calving grounds.

The Humpback migrates to the tropics and the Southern Right Whale to the temperate waters of southern Australia.

Humpbacks travel thousands of kilometres each way, rivalling the journeys of other animals, such as some bird species, to giving birth and mate. This two to three month migration is even more remarkable when you consider that the whales do not eat until they return to the cooler temperate waters of southern Australia.

The northern journey begins in June. The whales travel, usually in groups of three or four, in some cases within a kilometre or two of the coast, up the east and west side of Australia to the warmer tropical waters off north Queensland and northern Western Australia

Births

The birth of a Humpback at sea has never been observed but we know it occurs during the migration as new born calves are seen returning with adults in September/October (spring). The interval between births is generally two to three years so not every whale makes the journey each year.

Southern Right Whales' winter migration to warmer waters is a much shorter journey. The reasons however are the same. Calves need to be born into the warmer waters of southern Australia. These whales, often solitary, used this opportunity to socialise and mate.

Thermoregulation

Marine mammals are well adapted to life in the water. Pinnipeds, sea otters and polar bears are amphibious (able to operate on land and in the water). Sirenians and cetaceans spend all their time in the water.

Keeping a constant body temperature is the most serious challenge facing warm-blooded mammals in an aquatic (watery) environment.

Most marine mammals have an insulating layer of fat called blubber that keeps their bodies warm and buoyant. Blubber is rich in lipids (fats or fatty material that cannot dissolve in water) and stores large amounts of energy. Sea otters keep their body temperature constant with a dense (thick) layer of fur that traps a layer of air next to the skin so that their skin never gets wet.

Polar bears and some pinnipeds have a thick layer of fur and a blubber layer.

Another way marine mammals control their body temperature is by controlling their blood flow in a process called vasodilation. During vasodilation, blood flow increases to and from peripheral vessels near the surface of the flippers, flukes, and fins.

Countercurrent heat exchange allows cold blood returning to the body core to be warmed up by exhanging heat with arteries going to the periphery (flukes and flippers).

Diving

All marine mammals have special traits that allow them to dive deep and stay underwater for a long time. At some point, all must return to the surface to breathe. Whales and dolphins breathe through single or paired blowholes on the dorsal (back) surface of their head.

At the surface, they quickly inhale and relax the muscular flap to close it so they can dive

is directed away from tissues that can handle low oxygen levels and toward the heart and brain where oxygen is needed most. During diving, the heartbeat slows down. Some champion divers are the sperm whales. They can dive more than 1600 meters (over a mile) and may remain submerged for an hour or more!

Another champion diver, the elephant seal can dive more than 1500 meters (4920 feet) and stay under for two hours. Bottlenose dolphins can dive to depths of 540 meters (1770 feet) and remain underwater for 8-10 minutes.

Camouflage

To blend into their environment, some marine mammals have countershading (their top side is darker that their underneath surfaces). This coloration, typical of many marine mammals, provides camouflage. The result is that predators or prey do not see a contrast between the animal and the environment because the top blends in with dark depths when viewed from above and

the light belly blends in with the sunlit surface when seen from below. To the right is a picture of an hourglass dolphin illustrating the general pattern of dark upper dorsal coloration and light ventral (belly) coloration seen in many marine animals

Another example of camouflage is the coloring of the polar bear. The polar bear is white to blend in with its snowy environment. When sneaking up on prey, the polar bear will cover its black nose with its paw to blend in perfectly with its surroundings.

Sensory Systems

Pinnipeds have large eyes for seeing in the low light conditions often found underwater. In cetaceans, the eyes are located on the sides of the head, but focus forward. Both the pinniped's and cetacean's eyes are adapted to see well underwater. As a result, their in-air vision suffers.

Manatees have small eyes and fair to poor eyesight. They seem to be farsighted and rely on touch to identify objects close up.

Pinnipeds have small olfactory (sense of smell) lobes, and evidence shows that smell is important when interacting with other pinnipeds. Toothed whales do not have a sense of smell, but baleen whales do have some olfactory nerves. Cetaceans have taste buds at the base of their tongue, and the common dolphin and the bottlenose dolphin are able to distinguish (tell apart) certain smells.

Manatees have a good sense of smell and are often selective in their food choices. Sirenians have many more taste buds than their cetacean cousins, and this may contribute to their choices of food. Polar bears have an acute sense of smell, and it is the most important sense for detecting prey on land. A polar bear can smell a seal more than 20 miles away!

Mammals -Migration & Distribution

Marine mammals are widely distributed throughout the ocean. Some migrate and inhabit many different waters while others confine themselves to one small area. Migration is a regular journey between one region and another, usually associated with seasonal changes or breeding and feeding cycles.

Polar bears are found throughout the Arctic and the majority of them are found near land masses at the edge of the polar basin. Polar bears travel over the whole year within individual home ranges. Home range size depends on access to food, mates and dens. They also prefer to travel on sea ice; therefore, their ranges are limited by the amount of sea ice that forms in the winter.

Sea otters are found along the Pacific Coast of the United States, Canada and Alaska.

Pinnipeds and cetaceans make long-distance seasonal migrations to rookeries (breeding grounds) or warm-water birthing grounds. Reproduction and migration are often timed with seasonal changes in the availability of food for the adults and young. Many arctic pinnipeds migrate with the movement of food, but also with the seasonal movement of the ice pack.

All living sirenians are found in warm tropical and subtropical waters. They migrate into warmer waters during the colder months of the year when the water temperature drops below about 68 degrees F (20 degrees C). Manatees are found in the warm waters of the West Indies, Florida peninsula and the Amazon Basin. Dugongs are found in the Indian and western Pacific Oceans, northern Australia and the Persian Gulf

Gray Whales are baleen (filter-feeding) whales which are seen regularly along the California Coast each year during their migration. Like most of the larger baleen whales, they migrate each summer to cold, productive, Arctic waters to feed, returning to protected Mexican lagoons each winter for breeding and calving. Pregnant females lead the way on the South-bound journey, anxious to get to the protected lagoon and give birth.

The calf must be born in warm water as it is missing a thick layer of blubber to protect it from the cold. Females with calves lag behind on the northward migration, following the shoreline closely to avoid predators. Whales travel southbound from December through February, northbound March through May. The whales are recognized by having a low, heart-shaped blow, their mottled grey color, and lack of a dorsal fin. A dorsal ridge with several bumps goes down the center of the back

Marine Mammals

•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.

Marine Mammals

•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

Marine Mammals

•There are two sub-orders...Odontoceti (toothed whales) equipped with peg shaped, spade like 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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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)

•Order Sirenia related to ancestral Proboscidea (elephants)

•Separate since early Eocene sluggish, inshore marine and freshwater dwellers

•no hind limbs

•herbivores on vascular aquatic grasses and seaweeds

•Family Dugongidae Dugong dugon Indo-West Pacific Ocean-Mozambique and Red Sea to Fiji-Fossil evidence from Atlantic

•Marine bays and estuaries

•Rare everywhere except northern Australia

•Up to 3 m long 420 kg (930 lbs.)

•Feed on grass tops and roots and rhizomes

•Tusk-like pair of teeth in lower jaw

•Hydrodamalis gigas --Steller’s sea cow

•Known only from the Kommander Islands of the Bering Sea

•First described in 1741 by Georg Steller on the Bering Expedition

•Probably less than 1500 in whole population then

•7.5 m (25 ft) long, some 7 tons

•Fed on seaweeds, especially around creek mouths

•Very docile and unafraid of humans

•Monogamous family groups with the young herded and protected by the parents

•No teeth, but horny tuberculated plates in mouth

•External bristled lips and internal lips also

•Small lidless eyes

•No external ears

•Forelimbs about 2 ft. long, with horse-like hooves set with brush-like bristles

•no hind limbs

•1 inch thick hide with 4-9 inch blubber layer

•Intestine was 20 x body length

•Eaten by marine mammal hunter from Russia for beef-like meat and almond-tasting oil

•Last one was reported seen in 1768 (27 years after first one was seen)

•Family Trichechidae mainly confined to freshwater in geologic past

•now found in freshwater and coastal areas

•up to 4.5 m long, 600 kg. (1320 lbs.)

•Feed on green parts of a variety of vascular aquatic plants alternately feed and rest for short periods throughout the 24 hr day with no apparent activity cycle

•average submergence time is 4-5 minutes

•blunt peg-like teeth formed at rear of jaw and move forward throughout life and are lost from the front

•mildly social

•three sp. (all in Atlantic Ocean basin)

•Trichechus inunguis…Amazon manatee Most derived, most riverine

•Trichechus manatus…Caribbean manatee

•Florida to Brazil, coastal and estuarine

•Trichechus senegalensis West African manatee Tropical west Africa, coastal and estuarine

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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

Order Pinnipedia

Family Odobenidae

•Pacific walrus Odobenus divergens

•Arctic Ocean from Cape Chalagaski, Siberia (170o E) to Banks Land, Canada --south to Kamchatka , Bering Sea

•Atlantic walrus Odobenus rosmarus

•Atlantic Ocean from eastern Canada to Spitsbergen and Franz Josef Land--south to Sable Island, Nova Scotia

•no external ears, hind feet (flippers) can be turned forward, both sexes with long tusks, male larger than female, 18-24 teeth

•Eat benthic invertebrates, mostly clams flat peg-like teeth

•Long muzzle bristles

•young born on beaches or on ice floes

•tusks used as a defense or for hauling out on ice ?

•Preyed on by killer whales, polar bears, and man

Family Otariidae 14 sp. eared fur seals and sealions

•external ears, hind feet (flippers) can be turned forward,

•male larger than female,

•34-38 teeth,

•swim with fore limbs fur seals

•pointed snouts and smaller bodies

•sealions blunter snouts and larger bodies

•most feed on fishes, but some on squid and some on benthic invertebrates

•air retained in under fur, but do possess a blubber layer, too

•some offshore and some only coastal

•9 in Southern Hemisphere, 5 in Northern

•all breed and give birth on shore in rookeries

•territorial males are polygamous and maintain harems

•One young per female per year

•Sexually mature at about 10 years and live 30-50 years

•shed fur once per year

•most sp. heavily hunted in 1700s and 1800s for fur and oil

Family Phocidae 19 sp. hair seals

•no external ear,

•hind feet (flippers) cannot be turned forward,

•no great differences in sizes of male and female,

•swim with hind limbs most feed on fishes, but some on squid and some on benthic invertebrates and some on zooplankton

•air retained in underfur, but do possess a blubber layer, too

•Some are very deep divers

•some offshore and some only coastal

•5 in Southern Hemisphere, 14 in Northern Hemisphere

•2 sp. found only in large lakes

•some breed on shore in rookeries with polygamous males others breed on ice floes

•others breed in shallow water

•some phocids shed their skin!

Marine Mammals

•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.

Marine Mammals

•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.

Order Carnivora

Suborder Fissipedia

Family Mustelidae

sea otter Enhydra lutris

• smallest marine mammal

• Along margins of kelp beds along coasts of North Pacific -Southern Kamchatka peninsula to Kurile Island -Bering Sea islands Alaska south to Southern California and Channel Islands 

•eat sea urchins, mollusks, crabs, fishes, and seaweeds

• 15-20 lbs/day/otter 

• Collect from bottom down to 100 ft or so, crack and eat at surface 

• layer of air trapped in thick fur provides most insulation No blubber 

•sleep at surface of water 

•rarely go ashore 

• give birth in water 

•Preyed upon only by killer whales and man 

•Commercial taking began in 1742 at the Kommander Is by the Vitus Bering expedition……

•Collected by spear or club or coarse mesh nets from boats Commercial catch continued until 1910, when they became the first species to receive international protection

•Strong resurgence since 1970s 

•Conflict with abalone fishermen 

•Possible increase in killer whale predation   

• chungungo, sea cat Lontra (Lutra) felina

•kelp beds along coast of southern Chile

• sea mink Mustela macrodon

•known only from bones in Indian middens and hearsay of unusually large mink furs 

•coast of Maine

•could be just unusually large individuals of freshwater minks  if real, then extinct since about 1700

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•Sea Otter

• Enhydra lutris

•STATUS: Threatened off California. DESCRIPTION: The sea otter has the thickest fur in the animal kingdom. Unlike other marine mammals, the sea otter does not have a layer of blubber (fat) to help keep it warm. If an otter’s fur gets coated with oil or any other substance, it can easily die from cold and exposure.

Marine Mammals

•SIZE: The sea otter is the largest member of the weasel family. Southern sea otters typically reach about four feet in length. Females average 45 pounds, while males average 65 pounds. Northern sea otters can reach up to 100 pounds.

Marine Mammals

•POPULATION: Today there are about 2,000 southern sea otters off the coast of California. There are between 27,500 and 52,500 northern sea otters residing in Alaska, Canada and Washington. There are approximately 15,000 in Russia. Two hundred years ago, demand for the otter’s pelt nearly led to its extinction.

Marine Mammals

LIFESPAN: Male sea otters live an average of ten to 15 years, while female sea otters live an average of 15 to 20 years.

•RANGE: The sea otter’s historic range stretched from Japan, along the coast of Siberia and the Aleutian Chain and down the Alaska, British Columbia, Washington, Oregon and California coast to Baja California.

Marine Mammals

•HABITAT:Shallow coastal waters of the northern Pacific.

•FOOD:Sea urchins, abalone, mussels, clams, crabs, snails and about 40 other marine species.

•BEHAVIOR: Sea otters are the only mammals other than primates known to use tools. Otters use small rocks or other objects to pry prey from rocks and to hammer or pry open their food.

Marine Mammals

•They can dive up to 330 feet when foraging for food. Otters rest in coastal kelp forests, often draping the kelp over their bodies to keep from drifting away.

•OFFSPRING: Sea otters breed throughout the year. Females give birth to one pup after a gestation period of six to eight months.

Marine Mammals

•THREATS: Oil spills, habitat loss, gill net entanglement and conflict with shellfish fisheries.

•PROTECTION: *CITES, Appendix I, Marine Mammal Protection Act, Endangered Species Act

•*Convention on International Trade in Endangered Species of Wild Fauna and Flora, an international treaty with more than 144 member countries.

Marine Mammals

•Appendix I listed species cannot be traded commercially. Appendix II listed species can be traded commercially only if it does not harm their survival.

•

Family Ursidae polar bear

Ursus (Thalarctos) maritimus

•circumpolar Arctic Ocean

•eat seals, fishes

•may be found 100s of miles from land on ice floes, but generally near coast

•give birth on land

•aren’t visible to infra-red sensors

•excellent insulation

•are black to UV sensors….reflect all UV?

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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)

Marine Mammals

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

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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

Marine Mammals

•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

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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).

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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

Marine Mammals

•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.

Marine Mammals

•It takes a rorqual two seconds to exhale and inhale 1500 gallons of air and man 4 seconds to exhale and inhale a pint.

Marine Mammals

•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).

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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!

The calf must be born in warm water as it is missing a thick layer of blubber to protect it from the cold. Females with calves lag behind on the northward migration, following the shoreline closely to avoid predators. Whales travel southbound from December through February, northbound March through May. The whales are recognized by having a low, heart-shaped blow, their mottled grey color, and lack of a dorsal fin. A dorsal ridge with several bumps goes down the center of the back

Oxygen Storage Capacity

Diving mammals do not have larger lung volume to body size ratios than terrestrial mammals, yet they can dive for extended periods of time without breathing (Schmidt-Nielson, 1997). They have evolved alternative mechanisms for increasing the amount of oxygen they carry. The lungs, blood, muscle, and spleen are where the most noticible differences between terrestrial and diving mammals oxygen storage capacities occur.

Seals do not use the lungs to store oxygen. As seen in the graph below, when diving, there is significantly less oxygen in the lungs of a seal in than the lungs of a human. The lungs can not store air as a seal dives because of the increased risk of decompression sickness it would impose on the seal.

A seal's blood has a higher oxygen-carrying capacity than a human's because a seal has a greater blood volume than a human.

Because there is more blood in seals, there are more red blood cells (RBCs) (Schmidt-Nielson, 1997). The increased number of RBCs increases the amount of hemoglobin, a blood pigment found in RBCs that carries oxygen, in seals. A seal's RBCs are composed of less water than a terrestrial mammal's, so even at the cellular lever, a seal is designed to carry more oxygen (Castellini and Castellini, 1989).

The amount of RBCs that the blood can carry is limited. If there are too many cells, then the blood gets too viscous for the heart to pump effectively, so marine mammals have accessory methods to store oxygen. An additional place for marine mammals to store oxygen is in myoglobin, an oxygen binding pigment found in the muscle tissue (Schmit-Nielson, 1997).

Myoglobin is highly concentrated in seal muscle tissue, making it very dark, and allowing the seal muscle tissue to hole more oxygen that human muscle is capable of holding.

Finally, marine mammals store more oxygen in other tissues of the body than humans do, thus giving them the ability to store more oxygen than humans.

The spleen is a very vascular organ which stores large amounts of blood and red blood cells. These characteristics make it an ideal source of oxygenated red blood cells during a seal's dive. Zapol et al. (1989) estimate that 60% of the red blood cell mass is stored in the spleen. The seal capitalizes on the vasoconstriction that occurs during diving and constricts the spleen as well as peripheral blood vessels. The plasma volume (PV) remains constant while the circulating red blood cell volume increases.

The increase in hematocrit (Hct.), or proportion of RBCs to plasma, correlates with the blood volume (BV) composing a larger percent of body weight (BW). View the diagram below for a graphical representation of what occurs to the spleen during diving. The release of red blood cells helps reduce carbon dioxide and lactate buildup as well as high nitrogen tenions while increasing the oxygen content of the blood for the first 10-12 minutes of a dive (Zapol et al., 1989).

Seals can dive for much longer than would be predicted by evaluation of oxygen stores only. The oxygen storage capacity is only one of may adaptations that seals have to help them dive for extended periods of time. Click on the following buttons to find out about the other responses marine mammals have that help them dive efficiently.

. Diving ability - respiratory and circulatory adjustments.

1. times and depths for various species – figure 12.2 p. 5
2. problems: depletion of O2, buildup of CO2 and lactic acid by-products, need for high amount of energy during dive.
3. apneustic breathing pattern - short breath, hold for long periods

· large whales can empty their lungs of 1500 liters of air and refill in 2 seconds!

· see fig. 12.23, p. 5

4. ability to remove 90% of O2 from air (compare to 20% for humans

5. avoid nitrogen poisoning (the bends)

a. lungs contract and collapse under pressure up to 250 atm
b. with no air in lungs, there is no risk of bubbles forming in blood during descent. This would be dangerous because it can cause paralysis

6. have lots of blood for extra O2 storage

· 21% of body weight is blood in sperm whale

7. extremely lowered heart rate – as low as 20% of normal

Aftermath of whaling (Table from Carwardine, 1999)

Whales and other marine mammals have special adaptations that allow them to hold their breath longer than a person. Believe or it not, though, breath holding isn’t the key -- oxygen conservation and storage is. Seals have so much oxygen in their body, you might be surprised to learn they actually exhale before they dive!

Some of the ways marine mammals conserve or store oxygen include:

Reduced heart rate: When a marine mammal dives its heart rate slows down to conserve oxygen. Some drop from 120 beats per minute to 4 to 6 beats.

Carrying oxygen: Marine mammals have a high concentration of oxygen-carrying cells in their muscles and blood.

More blood equals more oxygen: Marine mammals have two to three times more blood than a human. Other adaptations also include a network of spiral blood vessels that act as reservoirs for oxygen rich blood.

And, seals and sea lions store oxygenated blood in their extra-large spleen (which can be 45% of their body weight).

Recirculating the blood: For extended dives the blood is shunted or recirculated to only the most essential organs, like the heart, lungs, and brain. How long a marine mammal stays underwater depends on the species, where it lives, and what it eats.

Here are some examples of average diving times:

A male Northern elephant seal’s dive is about 20 to 35 minutes, a harbor seal -- 3 to 7 minutes, and a walrus -- 10 minutes. A bottlenose dolphin may stay under 8 minutes, a killer whale 10 minutes, an Amazon river dolphin can stay under only 2 minutes.

Tidbit: Seals’ diving capabilities are often underestimated. The breath holding ability of most seals is greater than most whales

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

•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.

Marine Mammals

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

•

Marine Mammals

•Eared seals use their front flippers for swimming and hind for walking on land.

•Marine mammals are warm-blooded and nourish their young on mothers milk.

•Blubber, a thick layer of fat insulates the body as well as providing buoyancy, padding and a source of energy when food is scarce

•The horzonital tails of the whales are adaptations that enable them to dive and surface easily.

Marine Mammals

•Eared seals use their front flippers for swimming and hind flippers for walking on land.

•True seals are usually found in cold water and eared seals in warmer water.

•Cetaceans can't survive on land because of their lightweight skeleton which can not support the body out of the water.

Sperm whales can dive to depths of 3000 feet and stay down for 90 minutes.

Marine Mammals

•Baleen whales feed on plankton

•Cetaceans have good eyesight but poor senses of smell and taste.

•The tusk of the walrus is not used to catch seals.

•Sea otters have no blubber and that is why they have thick fur.

•Baleen whales have no teeth and feed on plankton.

Marine Mammals

•Porpoises have a stubby-nose form and Dolphins have a long-beak form.

•The decrease of kelp beds is related to the increase of sea urchins and decrease of sea otters.

•The retia mirabilia only functions when the marine mammal is diving

•Baleen whales are an example of ____ nekton

Marine Mammals

•

•The statement that best describes the adaptation of the Cetaceans skull concerning its nostrilsis that the nostrils have migrated to the top of the skull and form a blowhole

Dolphins!!

life style of dolphins.

Mythology

• The Roman and Greek Mythology put pictures of dolphins in their art

• Sailors always looked for dolphins for a smooth voyage and for good luck

Kinds and Names

• Wide sided, Bottle nosed, and common

• Males-Bulls

• Females-Cows

• Babies-Calves

• Herd-lots of dolphins

• Shark-Enemy

• Life expectency-25 years

Pregnancy and Babies

• Mate in spring

• Babies-Calves

• 10-12 months

• Babies born one at a time

• 1/3 as long their mother

• Males take no part in taking care for the babies after they are born

Bodies

• Torpedo Shaped bodies

• Paddle shaped flippers

• Tail-Flukes

• Lungs

• Blowhole

• Lots of teeth

• Dorsal fin on back

How They Move

• Slap flukes up and down

• Use flippers to make sharp turns and to stop

• Speeds- 20 to 25 miles per hour

Echolocation

• Use to know where objects are in the water

• Locates by clicking sounds

• The Melon, a part in the head, directs the noise forward

• Sounds reflecting off the object

• By listening to the sound they determine where the object is

Communication

• Whistles and Clicks {phonations}

• Blowhole

• Slapping there flukes on the surface of the water

Diving

• Most do not dive deep

• Some are trained to dive 1,000 feet

• When dive their lungs collapse and heart rate slows down

• These actions help the dolphin adjust to the pressure

Training

• Most are bottle nosed dolphins

• By watching others they invent their own behavior pattern

• Jump through hoops, throw balls through nets, walk backwards on their flukes

Hunters

• In 1972 passed law limiting killing

• Several nations kill them

• Most responsible are the tuna fishing people including Japan and Sri Lanka

• Accidents drown them, such as getting caught in fishing nets

• The hunters eat the meat

Objectives

• Taxonomy

• Anatomy

• Restraint and handling

• Training

• Physical exam

• Signs of illness

• Diagnostic modalities

TAXONOMY

• Carnivora

– Polar Bears

– Sea Otters

– Pinnipeds

• Sea Lions and Fur Seals – Otarids

• Seals - Phocids

• Walruses - Odobenids

• Sirenia

– Manatees

– Dugongs

• Cetaceans

– Untoothed Mysticetes - i.e. Gray whales

– Toothed Odontocetes – i.e. Whales, Dolphins, and Porpoises

No Pinnae!!

TAXONOMY

• Carnivora

– Polar Bears

– Sea Otters

– Pinnipeds

• Sea Lions and Fur Seals – Otarids

• Seals - Phocids

• Walruses - Odobenids

• Sirenia

– Manatees

– Dugongs

• Cetaceans

– Untoothed Mysticetes - i.e. Gray whales

– Toothed Odontocetes – i.e. Whales, Dolphins, and Porpoises

TAXONOMY

• Carnivora

– Polar Bears

– Sea Otters

– Pinnipeds

• Sea Lions and Fur Seals – Otarids

• Seals - Phocids

• Walruses - Odobenids

• Sirenia

– Manatees

– Dugongs

• Cetaceans

– Untoothed Mysticetes - i.e. Gray whales

– Toothed Odontocetes – i.e. Whales, Dolphins, and Porpoises

MAN and the OCEAN ENVIRONMENT

1. Marine Pollution

2. Low O2, high temp., dredging, wastes

3. Removal of marsh lands and wet lands

4. Benefits of the sea

5. Uses of ocean to man

Throughout history the ocean has played a vital role in the development and growth of civilization, and humans have considered the ocean to be an unlimited source of food and a bottomless garbage dump. With a population of 6.5 billion most fisheries are fully exploited and ocean dumping is causing measurable contamination of the food supply.

 Some negative influences of man...

1. The use of pesticides and other agricultural chemicals to help crop yield on land has harmed food production in the ocean.

2. A process called BIO-MAGNIFICATION, concentrates toxins such as DDT, PCB'S and mercury in tissues of consumer organisms...many of which are used for human consumption.

3. Alternates to ocean dumping must be sought to prevent further contamination of the food supply.

4. Economic and ethical issues of commercial whaling works these animals toward extinction.

5. Destruction of marshlands by draining and dredging and attempts to control beach erosion in spite of a world wide rise in sea level.

The London Convention discourages dumping at sea
The London Convention is a nickname for a United Nations administered agreement on preventing pollution produced by dumping wastes and other harmful substances at sea. This treaty classifies materials according to potential harm to marine life and humans. It bans dumping some substances and regulates dumping others §.

Currently the U.S. dumps only dredged materials, although other countries still dump sewage sludge and non-toxic industrial waste §. The U.S. and other parties to the London Convention are observing a moratorium on dumping low-level radioactive waste

 POLLUTION

For the past 100 years, contaminants like oil, PCB, DDT, heavy metals, radioactive wastes, sewage sludge and garbage is introduced into the sea .

OIL due to tanker accidents, oil rig blowouts, daily oil washed off roadways into sewers and into water, ships pumping waste oil from bilges/ballast, seepage from garbage dumps and

natural seepage from the ocean bottom. (the largest discovered off Trinidad at 100m /100m thick and contains 1 megaton of oil)

Oil harms the environment by

1. covering or poisoning

2. birds die of starvation because they can't fly and no insulation

3. ingest oil from feathers while trying to clean

4. damage the liver and vital organs

 Crude oil released into the sea usually floats although some sinks .

Oil in intertidal zones...tides bring a new blanket of oil to cover oysters, clams, mussels etc interfering with feeding and breathing. The devastation usually occurs initially but recovery usually occurs with time. More serious than the oil itself has been the various chemicals used such as detergents used to break it up or disperse the oil into

the water.. The Tory Canyon disaster in 1967 the chemicals were shown to cause more mortality to marine organisms than the oil itself.

.

When it comes to mixing oil and water, oceans suffer from far more than an occasional devastating spill. Disasters make headlines, but hundreds of millions of gallons of oil quietly end up in the seas every year, mostly from non-accidental sources §

The graph below shows how many millions of gallons of oil each source puts into the oceans worldwide each year

Down the Drain: 363 Million Gallons

Used engine oil can end up in waterways. An average oil change uses five quarts; one change can contaminate a million gallons of fresh water. Much oil in runoff from land and municipal and industrial wastes ends up in the oceans. 363 million gallons §

Road runoff adds up
Every year oily road runoff from a city of 5 million could contain as much oil as one large tanker spill §.

Routine Maintenance: 137 Million Gallons

Every year, bilge cleaning and other ship operations release millions of gallons of oil into navigable waters, in thousands of discharges of just a few gallons each. 137 million gallons §

Up in Smoke: 92 Million Gallons

Air pollution, mainly from cars and industry, places hundreds of tons of hydrocarbons into the oceans each year. Particles settle, and rain washes hydrocarbons from the air into the oceans §.

Natural Seeps: 62 Million Gallons

Some ocean oil "pollution" is natural. Seepage from the ocean bottom and eroding sedimentary rocks releases oil.

Big Spills: 37 Million Gallons

Only about 5 percent of oil pollution in oceans is due to major tanker accidents, but one big spill can disrupt sea and shore life for miles §. 37 million gallons §

Crude oil from a tanker that ran aground
Kill Van Kull Channel, between Staten Island and New Jersey, 1991

Offshore Drilling: 15 Million Gallons

Offshore oil production can cause ocean oil pollution, from spills and operational discharges.

Pelagic...eggs and larva drift in oil slicks, they can't swim and there is less photosynthesis.

Pelagic tar...some components evaporate or dissolve but lots sink to the bottom to be trapped in sediments.

Right whales ingest floating tar and sperm whales feed off bottom sediments (complete with tar!)

 Sewage and Garbage

The discharge of human sewage and garbage into the coastal waters is practiced throughout the world. The sewage may or may not have had some treatment before discharge. It adds a large volume of small particles to the water and also large amounts of nutrients.

In small volumes and with adequate diffusing pipes, it is difficult to detect long-term effect on the communities of the open coast. In large volumes and in semi enclosed embayments, the effect can be devastating.

Two examples...

Southern California..LA area discharges 330 million of sewage per day at the Whites Point outfall off the Palos Verdes Penn.

Studies around the outfall and others in the area revealed that sewage has caused significant degradation in benthic invertebrate communities in areas near the outfall, kelp beds disappeared near the outfall, more urchins, diseased fish more prevalent and about 4.6% of the Southern Cal. mainland shelf has been changed or degraded as a result of sewage discharge from 4 major outfalls.

Hawaii-Kaneohe Bay on Oahu's east side was subjected to a 10-fold increase in population and the bay was subjected to massive domestic sewage discharges, siltation from runoff during storms and resulted in the total destruction of the once beautiful coral reefs of this shallow bay. Once the discharges were eliminated from the bay, a remarkable recovery of corals and water clarity was reported!

In addition to sewage, large amounts of garbage are dumped into the ocean every year.

And then there is New York. The city dumps dredge spoils, sewage, chemicals, garbage, construction materials, which are dumped in such large numbers its visible from satellites. Sewage alone the 127 municipal discharges contribute 2.6 x 10⁹ or 2,600,000,000 billion gallons per day.

The dumping has dropped O2 levels near zero over extensive bottom areas off New Jersey, led to massive fish and shellfish mortalities, and even though most are dumped many miles offshore, some returns to contaminate bathing beaches (needles).

CHEMICALS

Worse than oil or sewage, which are at least visible, are various toxic chemicals produced by the industrialized nations which find their way into the oceans ecosystems.These chemicals are often transferred through the food chains in the sea and exert their effects in animals and places removed in time and space from its source.

Certain marine organisms also enhance the toxic effects of many chemicals because of their ability to accumulate the substances in their bodies far above that found in the surrounding water. Another factor that tends to increase the effects of chemicals on living systems is biomagnification in which the chemical increases in concentration in the bodies of organisms with succeeding tropic level

....this can lead to very high concentrations in the top predator. ..sometimes man!

Example..in the late 1930's, the Chisso Corp. of Japan established a factory on the shores of Minimata Bay to produce vinyl chloride and formaldehyde. By-products from the plant contained mercury and were discharged into the bay. Through biomagnification, the marine fishes and shellfish accumulated high concentrations of the toxic compound methyl-mercury chloride.

The fishes and shell fish were in turn consumed by the inhabitants of the area. About 15 years after the dumping of the mercury into the bay began, a strange permanently disabling neurological disorder began to appear among the inhabitants, especially the children. It was called Minimata Disease. The cause was diagnosed as mercury poisoning in 1959 but it took until the early 60's to discover the source from the factories.

and until the 1970's before Japan to stop dumping mercury into the sea.

DDT and Pelicans etc Radioactive wastes 

Biomagnification: how DDT becomes concentrated as it passes through a food chain

The figure shows how DDT becomes concentrated in the tissues of organisms representing four successive trophic levels in a food chain.

The concentration effect occurs because DDT is metabolized and excreted much more slowly than the nutrients that are passed from one trophic level to the next. So DDT accumulates in the bodies (especially in fat). Thus most of the DDT ingested as part of gross production is still present in the net production that remains at that trophic level.

This is why the hazard of DDT to nontarget animals is particularly acute for those species living at the top of food chains.

For example,

•spraying a marsh to control mosquitoes will cause trace amounts of DDT to accumulate in the cells of microscopic aquatic organisms, the plankton, in the marsh.

•In feeding on the plankton, filter-feeders, like clams and some fish, harvest DDT as well as food. (Concentrations of DDT 10 times greater than those in the plankton have been measured in clams.)

•The process of concentration goes right on up the food chain from one trophic level to the next. Gulls, which feed on clams, may accumulate DDT to 40 or more times the concentration in their prey.

•This represents a 400-fold increase in concentration along the length of this short food chain.

There is abundant evidence that some carnivores at the ends of longer food chains (e.g. ospreys, pelicans, falcons, and eagles) suffered serious declines in fecundity and hence in population size because of this phenomenon in the years before use of DDT was banned (1972) in the United States.

Channel Dredging

Channels are dredged deeper and wider so boats won't run into each other or run aground and until the day comes when

(1) no more boats are built, (2) they don't increase in length, beam and draft or (3) moving water stop dumping silt into channels, they will continue to be dredged.

Dredging can damage by tearing up marine habitat by releasing silt which smothers shellfish and cuts down sunlight penetration into the water, changes water current patterns,,

creates deep holes in an otherwise shallow and even bottom and the holes can collect detritus and form low oxygen conditions and the worse is the dredged material is usually dumped on the protective marshlands. Deeper channels can also allow denser salt water to travel further up the estuary increasing the salinities and bringing predators to an otherwise low salinity environment which can then feed of the oysters etc.

Sand, Gravel, and Coral

Island nations, with limited inland sources of building materials, turn to coastal sand and

Collecting coral to process for lime, Solomon Islands, 1988 Mining coral removes habitat of local marine species, and weakens coastal storm defenses. Rebuilding coral takes time because colonies of tiny coral animals grow slowly. Mined or dredged areas take a very long time to recover

Mining sand for landfill, Belize Sand and gravel are in demand as fill, and as an ingredient of concrete. Mining near shores may lead directly to beach erosion. Removing sand from river beds may also cause beach loss, because floods would have eventually brought that sand to beaches

Mariculture...farming the sea can add to world food production. (growing aquatic is aquaculture).

History...The Japanese/Chinese raised fish and Japan raised fish and the Japanese grew seaweed on ropes but the main problem with mariculture is

1. lack of suitable domestic organisms

2. gaps in knowledge of nutritional requirements and life cycles (larva stages)

3. need to duplicate the natural environment

4. lack of knowledge in relation to diseases of marine organisms.

Instead of trying to find all these, a way around it is to work out some, which can be done by interrupting the natural stages and leave the rest to nature.

There are 2 broad types of mariculture.

1. Duplicate environment artificially

2. Grow more effectively in the natural environment

1. Artificial settings are used in growing lobsters, shrimp, fish.

2. Ranching--rear young from artificially fertilized eggs and release 3 year old fish to ocean.

(most mortality occurs during 1st year of life)

Manganese and Other Metals Deep ocean basins are strewn with metallic nodules §. Composed mostly of manganese, they also contain nickel, copper, and cobalt. Pipelines running to ships or platforms could "vacuum" up these nodules, but no country or consortium is yet mining them, in part because of high costs compared to land-based mining §.

Mysterious manganese "marbles" lie strewn on the abyssal mud of the ocean's deepest basins. Most are larger than golf balls §. Each appears to have grown, pearl-like, around some nucleus-- perhaps a shark's tooth.

Maximum sustainable yield

In fisheries science, maximum sustainable yield or MSY is the largest long-term average yield/catch that can be taken from a stock of fish without depressing the species' ability to reproduce.

A typical MSY is about 80% of the total population biomass of the mature fish capable of reproduction. The maximum sustainable yield is usually higher than the optimum sustainable yield.

•Practical Considerations:

•Obtaining realistic values for fishing effort and catch per unit effort is not as straight forward as one would like. Catch is made up of:

•that retained for its value and eventually marketed

•that discarded at sea or dockside (typically 30-40%).

•portions of commercial species having little value (heads and guts)

• species with no commercial value

• undersized individuals

• restricted take individuals

• Catch is often lumped by fishers or processors into broad market categories including several species.

• Effort includes both gear and time.

• Effort may be simple: feet of gill netting or number of hooks on a long line per day or hour

• but it may also be complex, needing to account for:

• varying mesh size

• otter board size

• horsepower of boat

• use of electric "ticklers" to cause bottom fish to swim up into a trawl

• whether the boat uses a sonar fish locator and how up-to-date it is

• how experienced the captain is

• Even time can be complicated. Fisheries which involve pelagic schooling fish have both a search component and a fishing component. Employment of spotter planes will shorten the search time but not the fishing time.

• Obviously commercial records by themselves are inadequate, the fisheries manager must conduct additional surveys, sampling, and perhaps even covert observation to accurately determine both catch and effort.

•Data from the commercial catch should always be supplemented from fishery-independent data. Complicated statistical analysis is essential.

•Fatal Flaws:

•For years we have been managing commercial fisheries based largely on CPUE data. New reports of failed fisheries surface almost daily. Obviously fisheries management has been less than a sterling success. There are three main categories of reasons.

• Technical
Fisherpersons continually upgrade their gear, adding the latest gimmicks if they think they will help them turn a profit. Nets have become stronger and lighter; boat motors more powerful; refrigeration better so the fleets can remain out longer; fish-locators and navigational aids and record keeping vastly more accurate and afordable. We have been basing catch per unit effort on an effort component which has become subtly but vastly more efficient.

Political
Every management decision has a political component. Whenever a fishing restriction creates a real or imagined hardship for people, they protest, sometimes violently. Considering the tenuous data available, the efficacy of almost any management recommendation can be questioned. Politicians and bureaucrats tend to err on the side of people rather than fish (fish rarely complain).

High seas fisheries are governed by international treaties. Often the effect on the fish population is secondary to some other bargining point.

• Biological

• CPUE and Sustainable Yield are based on the assumption that an unexploited population will behave in a predictable fashion. An unexploited population is a fallacy. The process of evolution produced something to exploit any available resource.

• Much of our historic success at harvesting huge quantities from the sea resulted from the co-harvest of the other species that naturally exploited the species we were harvesting. We virtually eliminated most marine mammals and the largest species of fish very early on. That, of course, left their food supply for us to exploit and as we reduced them, we began to harvest their food supply. The history of our exploitation of the sea has been one of migration down the food chain.

• Predator species can't recover, even if we would let them, because we are taking all their food. Imagine trying to balance a MSY for anchovetta and tuna at the same time.

• Ecosystem destruction has resulted from many technological innovations including fish harvest techniques.

• Dams and diversions have disrupted life cycles of anadromous species,

• Dredging and filling to create residential, commercial, and agricultural properties has eliminated or damaged nursery grounds for many coastal species.

• Bottom trawls crisscrossing the most productive parts of the ocean floor have destroyed the substratum on which fish and their foods depended.

• Untold quantities of myriad industrial, agricultural, and medical chemicals have entered the ocean and potentially concentrated in biological systems where their effects include reproductive dysfunction.

HYRACOIDEA & SIRENIA:
Remnants of the Subungulate Radiation

.

Character states: Proboscidea Hyracoidea Sirenia

Carpal & tarsal bones x x x

Short, hoof-like nails 5/4 or 4/3 4 /3 4/

No clavicle x x x

Pectoral mammaries x x x

Abdominal testes x x x

“Horizontal molariform

tooth replacement x x x

SIRENIA: Unique among all orders?

• Habitat and diet ________ & _________

• A mere remnant of a once diverse group (20 genera) of the Miocene

• Distribution: Dugongidae & Trichechidae

• Four extant & one recently extinct species

SIRENIA: Unique among all orders?

• Habitat and diet ________ & _________

• A mere remnant of a once diverse group (20 genera) of the Miocene

• Dugongidae & Trichechidae compared

• Dugongidae (with forked tails): one species Dugong of Indonesia (Stellar’s sea cow: extinct)

• Trichechidae: Distribution of 3 species: W. African, Amazonian,

and West Indian or Florida Manatee

West Indian Manatee

• One of four species in a declining, endangered (?) order

• Characteristics of endangered species

• Physical characteristics and distribution

• Habitat requirements & Feeding behavior

• Reproduction: 5-15% of population in 1^st year calves

• Major causes of mortality

• Conservation: Recovery Plan & recent issues

• Current status: n ~ 1900, ~ 8% annual mortality

Characteristics of Endangered Species :

• Adapted to stable, undisturbed communities

• Low natality and low natural mortality

• Specialized, narrow habitat or environmental requirements

• Historically restricted in distribution, on periphery of range or low in density

Natural History of Manatees

• 2-3 meters long, 350-450 kg, no hind limbs

• Former range reduced to Florida & Puerto Rico

• Habitat: Shallow, warm fresh to marine waters with abundant aquatic vegetation

• Feed 4-6 hrs/day, consuming 25-35 kg/day

• Reproduction: Polygynous,

- 1^st breed at 4-6 yrs, every 3-4 years thereafter

- single calf, 390 day gestation, nurse ~1 year

• Is this characteristic of an endangered species?

. HISTORICAL EXTINCTION EVENTS

Some survivors from the Pleistocene have been driven to extinction during historical times by over-exploitation:

Sea Cow

This was heavy, slow-swimming marine mammal related to the manatee and dugong (Sirenians), but much larger (25-30 feet long). It was discovered in 1741 in the ocean around the Pribilof Islands in Bering Sea (far north Pacific Ocean).

. It was used as food by visiting sea-otter hunters, and was extinct by 1768, 27 years after its discovery.

Surviving relatives

A smaller (12 feet long) relative of the sea cow that is endangered by human activities is the Manatee (West Indian or Florida Manatee), a slow-swimming, friendly marine mammal that feeds on sea grass and lives in the coastal waterways of Florida and in other coastal

. areas around the Caribbean. There are about 2,000 animals in the population, but at least 200 die each year, mainly from collisions with speedboats. Florida's response to this problem has been to post "go-slow" signs on the waterways, and to rely mainly on voluntary compliance. They have also established some very small sanctuaries. These efforts are not working very well. The death rate has not declined; in fact collisions with boats

. killed a record number of 95 manatees in 2002. Save the Manatee Club is now filing lawsuits to try to get the government agencies to better enforce the laws protecting manatees.

. Despite the manatee's precarious situation, a consortium of Florida business interests is lobbying to get the mammal removed from the federal Endangered Species list.

The other surviving relative of the sea cow, the dugong, is also in serious trouble. Dugongs are found in a huge area from the Red Sea to the Pacific Coast of Australia and the Solomon Islands. They are so dispersed that accurate population counts have not been possible. The population at the southern end of the Great Barrier Reef was estimated at ~50,000 in the 1960's, but the number has fallen to about 4,000

. since then, due to habitat loss, entanglement in fishing nets and nets used to protect swimming areas from sharks . The Great Barrier Reef Marine Park Authority has established a chain of dugong sanctuaries to try to protect the remaining animals.

.

Dugongs, or sea cows as they are sometimes called, are marine animals which can grow to about three metres in length and weigh as much as 400 kilograms. They are the only marine mammals in Australia that live mainly on plants. The name sea cow refers to the fact that they graze on the seagrasses, which form meadows in sheltered coastal waters. As dugongs feed, whole plants are uprooted and a telltale-feeding trail is left.

. Relatives

Dugongs are more closely related to elephants than to marine mammals such as whales and dolphins, but their closest living aquatic relatives are the manatees. Manatees are aquatic mammals that live in freshwater rivers and coastal waters of West Africa, the Caribbean, South America and the southern United States (Florida). Another close relative was Steller’s sea

. cow, previously found in the northern Pacific. It was hunted to extinction in the 1700s by sealers for its meat. It grew almost three times as long as the dugong and fed on large algae (kelp).

Distribution

Dugongs inhabit shallow, tropical waters throughout the Indo-Pacific region. Most of the world’s population of dugongs is now found in northern Australian waters between Shark Bay in

. Western Australia and Moreton Bay in Queensland.

Life in the sea

Dugongs swim using their whale-like fluked tail and they use their front flippers for balance and turning. Their movements are often slow and graceful. Early explorers and sailors believed that they were mermaids because of their streamlined bodies and the large teats at the base of their flippers.

. They have a rounded head with small eyes and a large snout. The nostrils are at the top of the snout and, like mammals, dugongs must surface to breathe. However, unlike other aquatic mammals such as some whales, dolphins and porpoises, dugongs cannot hold their breath under water for very long. It is generally for only a few minutes, especially if they are swimming fast.

Dugongs have poor eyesight but acute hearing. They find and grasp seagrass with the aid of coarse, sensitive bristles, which cover the upper lip of their large and fleshy snout. Small tusks can be seen in adult males and some old females. During the mating season, male dugongs use their tusks to fight each other.

Life history Dugong list history is made of finely balanced population parameters.

.

. The slow breeding rate and long life span mean that dugongs are particularly susceptible to factors that threaten their survival. Throughout their worldwide range they are threatened by human impacts, particularly on their habitat.

. Declining numbers

Dugong numbers have declined dramatically in the past 40 years in the southern part of the Great Barrier Reef World Heritage Area south of Cooktown. Surveys indicate that numbers now appear to be fluctuating around a level that is far less than in the early 1960’s, and probably before. Whether the southern Great Barrier Reef population is continuing to decline

. , or is stable, or increasing, and at what rate, will not be known for many years but the species undoubtedly faces the threat of disappearing from the southern Great Barrier Reef. The Great Barrier Reef Ministerial Council, comprising the Commonwealth and Queensland Ministers for the Environment and for Tourism, is concerned about the decline and has instigated a number of actions to

. reverse the trend. Government departments, community groups and industry organisations are working to minimise the number of dugong deaths from human-related causes

. Experts consider that the decline in dugong numbers is due to unsustainable mortality from human-related causes such as habitat loss or degradation, commercial mesh nets (fish nets), shark nets set for bather protection, indigenous hunting, boat strikes, defence activities and illegal take.

•1999 surveys showed that numbers in the southern Area were back at 1986-87 levels (3993 ± 644),

. Sea Otters

When the Russian traders had exhausted the terrestrial fur-bearing animals they turned their attention to the sea otters that were discovered in 1741 in the north Pacific, on the Russian and Alaskan coasts.  At that time, there were between 150,000 and 300,000 otters living along the north American coast from Alaska to Baja California.

. From 1750 to 1790 most of the animals were killed by hunters, then they were too scarce to be worth hunting (they had reached "commercial extinction") and the trade collapsed. By 1911, when the otters received some protection through the International Fur Seal Treaty, there were only 1-2,000 animals left throughout their range. The population recovered well and the Alaskan (Aleutian Island) population

. reached a peak in the mid-1970s of about 50,000-100,000 animals. But from 1992 to 2000 it declined by 95% and now as few as 6,000 otters may remain in the entire Aleutian chain. This is just one part of a catastrophic ecosystem collapse that is occurring in the area.

Another population of about 2,400 sea otters survives along the California coast between Point Conception and Monterey Bay. 

. They are coming into increasing conflict with inshore fisheries for sea urchins.

. SEAL HUNTING

Fur seals.  The loss of furs from other sources was a major incentive leading to massive hunts for various types of seal. The animals were usually clubbed to death when they came ashore to breed. The pattern was familiar - the discovery of large populations of target species, the development of intensive hunting leading to extermination or depletion,

. the move to a new area. The first phase (1780-1820) was directed at the southern fur seal in many areas of the southern hemisphere and was carried out by sealers from Europe, Russia, Canada and the U.S. Each of the following areas was the site of a fur seal hunt until the population was either commercially extinct (depleted to the level where it was not profitable to hunt) or really extinct: 

. Off the west coast of Namibia in Africa, 40- 50,000 cape fur seal are taken each year.  This is about 10% of the world's sealing activity, and much of the profit comes from the sale of penises for the aphrodisiac trade in Asia.  Most of the seals are being killed by clubbing to death, which is claimed to be a humane method.  

. In the North Pacific, the northern fur seal was hunted on the Pribilof Islands in the Bering Sea, first by the Russians using Inuit labor after they had wiped out the sea otters. The slaughter went from 127,000 in 1791 down to 7,000 a year in the 1820's after 2.5 million had been killed. The population recovered after the Russian hunters moved to other areas, but after Alaska was sold to the U.S. in 1867 the hunting level

. went back up to 250,000 per year. This reduced the population again so that in the 1890's the number killed was down to 17,000 a year. It is now illegal to hunt fur seals, except for an exemption allowing Indians, Aleuts, and Eskimos to continue to hunt at a subsistence level (about 2000 a year).

Harp seal.  A massive seal hunt also developed in the North Atlantic

. , taking advantage of the huge harp seal population that breeds on the pack ice in winter around Labrador and Newfoundland. The sealers, from Newfoundland, focused on the newborn seals with pure white fur, although adults were also taken for their oil as well as fur. The Newfoundland sealing industry began in the early 19th century and peaked at about 600,000 animals per year in the 1850's. This ultimately

. led to reduction in the size of the herd to about one fifth of its original size, and the industry went into decline in the early 20th century. A 1998 study shows that the current level of hunting (350,000 animals killed in one season) is not sustainable, and 12 members of Congress have written to Secretary of State Madeleine Albright declaring their opposition to this hunt.  Again in 1999 Canada is being criticized for

. allowing 275,000 of these animals to be killed in spite of public opinion against it.  The adult harp seals are also hunted on a subsistence level further north by Inuit hunters, who use the meat for food but also sell the skins in order to pay for the snowmobiles, rifles, gasoline and ammunition that are used in their hunting activities.

Another herd of harp seals, at Jan Mayen Island in the Arctic ocean, was

. wiped out by a rapid boom and bust between 1840 and 1860.

Elephant Seals were hunted in the Pacific in the 1800s by whalers who wanted to supplement their catch. They were hunted for their oil rather than their fur or skin. Hundreds of thousands of these animals were killed in the southern ocean and along the coast of California. The southern population (a distinct subspecies) was

. saved when the Kerguelen and Macquarie Islands were turned into nature reserves, but in 1884 it appeared that the northern subspecies had been lost. However, a small colony of about 50-100 had survived on Guadalupe Island off the coast of Baja California.  The species was given protection by the Mexican and U.S. governments in the 1920s and the stock is now doing quite well. Today, there are

. approximately 160,000 northern elephant seals!  A large breeding population (~2000) now congregates on the beach at Ano Nuevo, fifty-five miles south of San Francisco, every winter. Seals and sea lions may have had many more breeding colonies on the mainland before they were eliminated by prehistoric hunting.

Walruses were killed for three centuries for their oil, skin, and ivory

. from their tusks. They were once abundant in the North Pacific, North Atlantic and the Arctic Oceans, but like the other seals, walruses were hunted almost to extinction. They are now protected in this country and the walrus population appears stable at about 200,000 individuals. 

.

Marine Mammal review and man and env rev

Marine Mammal Review-all correct!

1. Baleen whales are an example of Planktivorous nekton

2 How does a cetacean adapted to determine sound direction underwater? receive sound through the jaw

3 How is breathing similar in cetaceans and pinnipeds? both require a conscience effort

4.Mammals have all of the following characteristics except: they are ectotherms

5.Seals, sea lions, and walruses, which have blubber, flippers, and breed on land, belong to what order Pinnipedia

6. The largest group of pinnipeds is the: Seals

7Manatees and dugongs are related to what land animal? elephants

8.What order spends all of its life in the water? Cetacea

9. Baleen whales lack: teeth

10. Small, toothed whales are often referred to as: dolphins or porpoises

11. Marine mammals have many adaptations that allow them to spend much time

underwater. All of the following are examples of these underwater adaptations except for:Blood flow is shifted from the brain and heart to the gut and extremities.

12. Echolocation is a sense based on: sound waves

13. The spermaceti organ in sperm whales is thought to regulate buoyancy and: focus and direct sound waves

14 Breaching in whales is: leaping into the air and loudly crashing on the surface

15 Delayed implantation of the embryo allows pinnipeds to time the birth of pups with the arrival of the pregnant female in breeding areas

16. Immediately after their birth, the young of cetaceans: swim to the surface of the water

17. The tail of cetaceans ends in a pair of flukes

18 Evidence of cetaceans' terrestrial ancestry is found in small, useless rear-limb bones.

19 Fossils of the earliest whales do not have blowholes.

20 Sirenians are the only strict vegetarians among marine mammals.

· The pleated throat of many baleen whales is used like an expanding accordion to draw in large amounts of water and food.

· Cetaceans move their tails up and down while fishes move theirs side to side.

· Though they are air breathers, some seals have been recorded diving under water for over an hour.

· The blowhole of cetaceans not only allows for breathing air while most of the body is submerged, but also allows for breathing and swallowing simultaneously.

· Echolocation is used not only by most toothed whales, but also by some pinnipeds and probably some baleen whales.

· It is thought that cetaceans produce a mental " picture" of objects using echolocation sounds, since they can recognize objects by sight previously only sensed by sound.

· Breaching may serve as a warning signal or as a means of getting rid of external parasites.

· Most cetacean calves are born head-first in order for the newborn to quickly gulp in air at the surface.

· Pinnipeds often exhibit harem breeding with a dominant male mating with many females and fighting off other males.

· Eared seals use their front flippers for swimming and hind for walking on land.

· Blubber, a thick layer of fat insulates the body as well as providing buoyancy, padding and a source of energy when food is scarce

· . True seals are usually found in cold water and eared seals in warmer water.

· . The longest migration by a bird is 20,000 miles.

· Cetaceans can't survive on land because of their lightweight skeleton which can not support the body out of the water.

· Sperm whales can dive to depths of 3000 feet and stay down for 90 minutes.

· Cetaceans have good eyesight but poor senses of smell and taste.

· . Baleen whales have no teeth and feed on plankton.

· The decrease of kelp beds is related to the increase of sea urchins and decrease of sea otters.

· The retia mirabilia only functions when the marine mammal is diving.

· The tusk of the walrus is used to catch shellfish.

· Sea otters have no blubber

· Baleen whales feed on plankton.

· Birds have fat reserves because they feed constantly.

· The horziontal tails of the whales are adaptations that enable them to dive and surface easily.

· Eared seals use their front flippers for swimming and hind flippers for walking on land.

· Marine mammals are warm blooded and nourish their young on mothers milk.

· Gray whales migrate to Baja California in the winter to breed in the rich tropical waters, then to their summer breeding areas in the northern polar waters.

· The rounded fatty forehead structure, the melon, of toothed whales is thought to receive the sounds for echolocation.

· To dive deeply while breath-holding, all marine mammals rely mainly on a collapsible

· The bends condition is caused by nitrogen bubbles forming in the blood due to pressure changes in diving.

· Marine mammals avoid the bends because they don’t breath at pressures of the deep.

E 19 The following is true concerning whaling by humans:

A) Though most whale species in the Northern Hemisphere are endangered, the species around Antarctica are still plentiful due to their great distance from developed countries.

B) The International Whaling Commission has succeeded in banning all whaling in the world except for that by a few traditional tribal fishers.

C) American boycotts of tuna caught by nets that kill dolphins have succeeded in eliminating most net-caused dolphin deaths around the world.

D) All of the above.

E) None of the above.

Last Lecture review questions

1 A Mangrove forests in the tropics are being destroyed for human uses such as shrimp farming.

2 B Coral bleaching occurs primarily when coral polyps and their zooxanthellae are dead.

3 B Increased atmospheric carbon dioxide may be increasing the earth's temperature because this gas absorbs more infrared radiation from space coming from the sun.

4 A A great drop in atmospheric ozone levels, thought to be caused by CFCs, currently occurs over Antarctica.

5 B Eutrophication occurs when excess nutrients enter the ocean and feed decay bacteria, which deplete oxygen.

6 B Dumping of sludge (treated sewage) in the oceans has relatively little effect on marine life compared to dumping of raw sewage.

7 A Oil spilled in the ocean may last for years, but not forever because some of it evaporates and natural bacteria break down the rest.

8 A Oil spills can kill seabirds and some marine mammals by reducing their

9 B Most of the polluting oil in North America comes from tanker and pipeline spills.

10 B As chlorinated hydrocarbon pesticides enter a marine food chain, about 80-90% are degraded or lost at each trophic step (similar to the loss in production).

11 A One major result of the use of DDT as a pesticide was a large reduction in the reproduction rate of some marine birds due to weakened eggshell production.

12 B The use of DDT and other chlorinated hydrocarbon pesticides has been banned worldwide, and the problems they caused are now gone.

13 PCBs can evaporate, condense upon cooling, then get carried to the surface by precipitation, so that these toxins now are found in high concentrations in polar regions.

14 A The heavy metal mercury is more dangerous as an organic compound than as a metal.

15 B Radioactive waste must be ingested to have effects on marine life.

16 B Though marine thermal pollution is detrimental in the tropics, it is not much of a problem in colder regions because the increase in heat boosts ocean productivity.

17 A The European green crab is an example of a widespread alien species since now it is found in non-native habitats on both coasts of North America and in the southern hemisphere.

18 UNANSWERED One of the major contributors to the spread of exotic or alien species is ship ballast water.

19 A Threatened or endangered species include some whales, some sea turtles, and some shark species.

20 A Sustainable development refers to human use of resources that meet today's needs without affecting the ability of future generations to meet their needs.

21 A Planting vegetation that helps stabilize sand is a way to control beach erosion.

22 D Ccoral reefs are being threatened and destroyed by

A) dynamite and cyanide fishing.

B) clearing of terrestrial forests for agriculture.

C) an increase in bacterial and fungal diseases.

D) all of the above

E) both a and b

23 C The term endangered species is defined as

A) a species in decline due to human activities.

B) a species not in immediate danger of extinction, but potentially becoming so.

C) a species in immediate danger of extinction.

D) a species with a low number of individuals. answer for each question is indicated by a .

1 B The largest volume of seaborne trade is for food transport.

2 B Side-scan sonar can profile underwater archaeological sites covered with sediment.

3 B Virtually all maritime cultures now have adapted modern methods including powered boats and large nets.

4 B Tourism has greatly reduced harm to marine environments, since beautiful marine sites generally are preserved for tourists rather than being exploited for food or materials.

5 B The establishment of exclusive economic zones requires that foreign ships remain 200 miles away from the coast of a particular country.

6 A The United Nations Conference on Environment and Development in 1992 led to an agreement to protect the earth's biodiversity and the interests of traditional fisheries of native peoples.

1 B Food from the sea represents nearly half of all food eaten by humans.

2 B Most of the world's fishing people are employed in high-tech fishing fleets.

3 a Much of the clupeoid catch of the world is not eaten directly but rather converted into fish meal for use as animal feed.

4 A Cods of the Grand and Georges Banks off eastern Canada and the northeastern United States once provided one of the richest fisheries in the world but now are nearly gone.

5 Aa Purseseines are nets used to surround and trap large schools of fishes.

6 B The maximum sustainable yield for a fishery usually occurs when the harvested species population is at its highest possible level.

7 B Recent studies have shown that around 90% of the original stocks of large-size marine fishes remain.

8 A The term by-catch refers to currently underutilized species of marine animals caught when valuable species of animals are caught.

9 B Peru is one of the top fisheries countries because the Peruvian anchovy fisheries have been well managed since the 1950s.

10 B Unlike most harvested marine animals, the large numbers of krill around Antarctica are continuing to provide an increasing harvest each year.

11 A Open mariculture refers to the practice of raising marine organisms in enclosures that are open to more-or-less natural conditions.

12 A Salmon ranching relies on the ability of salmon to return to the site where they were hatched after maturing at sea.

13 A Medically useful compounds are being found in soft, immobile marine animals because these animals often defend themselves with noxious biochemicals.

14 B Manganese nodules are mounds of minerals created at the hydrothermal vents when hot water encounters cold seawater, triggering mineral precipitation.

15 A Manganese nodules on the seafloor may be economically useful because they contain not only manganese but other metals such as copper and cobalt.

16 A Evaporation of seawater to concentrate its minerals has been a technique used for centuries to obtain NaCl.

17 B Construction of devices to capture the renewable energy of the tides has no significant negative effects on the environment.

18 A Ocean thermal energy conversion is a technique that works best if the surface waters are much warmer than deeper waters, such as where there is a strong thermocline.

19 D The most important group of demersal fish caught for human use are the

A) clupeoids.

B) tunas and relatives.

C) salmon.

D) cods and relatives.

20 D The maximum sustainable yield of a harvested fish population depends on

A) the size and age of fish caught.

B) the reproductive and growth rates and lifespans of the fish.

C) interactions with competing species.

D) all of the above

E) both a and b