Arthropoda
•*Arthropods
make up the largest phylum with over a million species. They are jointed legged
found in every habitat. Crustaceans are the dominant class of marine Arthropods
such as lobster, shrimp and barnacles. The bodies are divided into a cephalothorax and abdomen.
Animal Kingdom
Arthropoda
•*The success
of Arthropods is due to their segmentation, and jointed external covering,
which allows for great mobility and strength. Growth is accompanied by shedding
or molting of the exoskeleton because otherwise growth would be impossible and
therefore imposes limitations in terms of size and growth.
Arthropoda
•*The success
of crustaceans in the sea is bought about by the gills, walking legs, swimming
legs, and feeding appendages. Water striders and tide pool insects are the
representatives of insecta and the arachnids are the
sea spider (Class Pycnogonida) and horseshoe crabs (Limulus).
Arthropoda
•*Now in
addition to crabs and lobsters, crustaceans make up a major component of plankton.
Crustaceans bear 5 pairs of appendages, two pairs of antennae, mouth parts. One
major line of crustaceans have evolved with large
walking animals. Extensions of the body wall at the base of the legs are used
for gills.
Arthropoda
•*The blood
contains hemocyanin, a copper based respiratory
pigment like hemoglobin. Sexes are separate and they develop through a series
of larval stages increasing size and numbers of segments with their associated
limbs.
Arthropoda
•*The simplest
larva stage is the nauplius larva, with three pairs
of appendages.. 1st and 2nd pair of antennae and
mandibles and often swims and suspension feeds (different functions of
appendages in larva than adult.)..larger larva develop
from the nauplius according to the type of crustaceans.
Some do bypass the nauplius by developing within the
egg.
Arthropoda
•*Small
crustaceans are everywhere, plankton, bottom, among sediments, in and on other
animals and plants. These are the bugs, flies and mosquitoes of the sea.
Arthropoda
•*Copepods The class Copepoda includes minute
sea inhabitants which provide a major source of food for fish, mollusks,
crustaceans and other animals as major components of the plankton. Some are
parasitic, infesting invertebrates or vertebrates (fish lice) and the free
living are small and capable of rapid population turnover.
Arthropoda
•*The large
first antennae may be used for quick escape but more commonly are act as
parachutes against sinking. They can filter feed on phytoplankton but can't
survive on this alone all year round because of low phytoplankton levels, and
sometimes seize large prey items like other members of the zooplankton.
Arthropoda
•*Barnacles
•Barnacles are
sedimentary marine crustaceans permanently attached to the substratum. For
protection barnacles have carried calcification of the cuticle to an extreme
and have a shell resembling that of a mollusk. The shell is derived from the
cuticle of the barnacle head and enclosed the rest of the body.
Arthropoda
•*Class Cirripedia, feed with six pairs of thoracic legs (cirri)
which can protrude though the shell plates to filter food suspended in the
seawater.. They can filter fine material, including
phytoplankton and even bacteria. They are hermaphrodites and carry out cross
fertilization between neighbors.
Arthropoda
•*There are 6 nauplius stages increasing size which swim and filter
phytoplankton over a period of a month or so before giving rise to a
non-feeding larva--the cypris larva.
Arthropoda
Arthropoda
•*This is the
sediment stage of the life cycle , able to drift and
swim in the plankton before choosing a settlement site in response to
environmental factor which the larva detects by an array of sense organs.
Arthropoda
•* Barnacles
colonize a variety of substrata including living animals such as crabs, whales
turtles, sea snakes and with this moving host, the barnacle does not need to
use energy in beating its cirri.
Arthropoda
•*Beach fleas
and other Amphipods the most familiar being the beach fleas or sand hoppers
found on sandy shores. The Amphipods are mostly marine and scavengers of
detritus able to creep using the thoracic periopods
(legs) and swim with the abdominal ones.
Arthropoda
•*They can
feed by scraping sand grains or filtering phytoplankton. The head and tail
curve downwards and they commonly are found among debris washed ashore. Whale
lice belong to this group of 5,000 species.
•Isopods are
found in many of the same environments as Amphipods and can be recognized by
their flattened top to bottom form. Fish lice belong to this group.
Arthropoda
•*The
giant isopod is the largest known member of the isopod family. It is a
carnivorous crustacean that spends its time scavenging the deep ocean floor.
Food is extremely scarce at these great depths, so the isopod has adapted to
eat what ever happens to fall to the ocean floor from above. It will also feed
on some of the small invertebrates that live at these depths.
Arthropoda
•*Giant
isopods are known to reach a size of over 16 inches in length and are one of
the largest members of the crustacean family. These animals are very
prehistoric in appearance. When threatened, the can roll themselves into a
tight ball where they are protected by their strong, armor-plated shells.
Arthropoda
•* They
have complex mouths that contain many components that work together to pierce,
shred, and disembowel live or dead prey. Giant isopods are all over the world
at depths of over 2000 feet.
Arthropoda
•*The eucarids...Krill and decapods
•The planktonic krill and decapods (shrimps lobsters, crabs) are
classified in the suborder Eucarida. they have a well developed carapace, fertilized eggs are
carried beneath the abdomen.
Arthropoda
•*Krill have
primitive features . All are marine, eggs hatch as nauplii, most have luminescent organs,
usually on the eyes, at the base of the 7th thoracic limbs and underside of the
abdomen. They are probably used for communication in swarming and reproduction.
Arthropoda
•*Krill are
pelagic and filter feed when phytoplankton conditions are suitable but
otherwise prey on larger planktonic organisms.
Phytoplankton rich seawater enters the tips of the legs and is strained as it
passes between the leg bases.
•Whale krill
reach 2 in. long and dominate the zooplankton of the Antarctic Ocean and is the
chief food of many baleen whales.
Arthropoda
•*In decopod, the first 3 pairs of thoracic appendages are
adapted as auxiliary mouthparts leaving 5 pairs of legs (decopods)
(and the 1st pair of these can be claws). Decopods
have been divided into swimmers (natantains) and
crawlers (reptantains) essentially, shrimps and
prawns ///and lobsters, crayfish and crabs.
Arthropoda
•*Now they are
divided morphologically into two sub-orders..shrimplike with many branched gills and planktonic eggs hatching as nauplius
larva (Dendrobranchiata) and Pleocyemata
which have gills lacking secondary branches and eggs carried on pleopods before hatching as zoeae.
Arthropoda
•*Prawns and
shrimp have no exact zoological definition and are interchangeable. The most
important shrimp families are the penaeids and sergestids. The first contain commercial shrimp. Most
pelagic shrimps are active predators feeding on crustaceans of the zooplankton,
such as krill and Copepods.
Arthropoda
•*Bottom
dwelling species are scavengers but range from carnivores to herbivores. Sexes
are distinct although some females pass through an earlier male stage
Arthropoda
•*Lobsters and
freshwater crayfish ...belong to a group known historically as macrurans (large tails) but now make up 3 infra-orders , Astacidea (lobsters, freshwater crays,
scampi) the Palinura (spiny and Spanish lobsters and Thalassinidae (mud lobsters and mud shrimps).
Arthropoda
•*Lobsters and
freshwater crays walk on the substratum on the four
pairs of back legs. The 1st pair is modified as a pincer. They are carnivorous
scavengers living in holes on rocky bottoms. The American lobster can reach
2'long (48 lbs) and live for 100 years. Fresh water crays
are omnivorous about 4 inch long.
Arthropoda
•*Squat lobsters
and hermit crabs are intermediate between lobsters and crabs. The abdomen is
variable in structure and hermit crabs probably evolved from ancestors that
lived in crevices and eventually specialized into using discarded gastropod
shells. Hermit crabs live as carnivorous scavengers on sea bottoms ranging from
bottom to sea shore and have a terrestrial existence in the tropics.
Arthropoda
•*Some
crustaceans that look somewhat like crabs belong to the Anomura.
They differ from true crabs by having at most only three pairs of walking legs
instead of four. Some anomurans are hermit crabs
which have a soft coiled abdomen protected by a snail shell. Most hermit crabs
are scavengers on dead plant or animal matter.
Arthropoda
•*Hermit crabs
are divided into families partly on which of the two claws is bigger. Other anomurans are the false crabs, flat and with similar sized chelipeds. The abdomen is a short flap tucked under the
thorax and there are only three pairs of walking legs.
Arthropoda
•*What is squat lobster? Technically,
it is a Pleuroncodes planipes.
Actually it refers to a whole family of lobster which has many many species.
•The name is will known in Europe as squat
lobsters and are regularly fished and marketed from the North Sea. It is one of
the smallest of commercial lobster species and is perhaps the most abundant.
Arthropoda
•*True crabs.
•These crabs
all possess a reduced abdomen held permanently flexed beneath the cephalothorax The reduction of the
abdomen has brought the center of gravity of the body directly over the walking
legs making locomotion very efficient and rapid. The sideways gait assists
this.
Arthropoda
•* The crab
shape is therefore the ultimate shape in efficient crustacean walking. They
live beyond the top of the shore to the deep sea to the hydrothermal vents 1.6
miles deep and on the other hand the ghost and fiddler crabs live at the top of
sandy and muddy shores up rivers and into fresh water.
Arthropoda
•*Most crabs
burrow to escape their predators descending back-first into the sediment . Some can swim using the last pair of legs as
paddles, run rapidly (ghost crabs) , pea crabs live in
the mantle cavity of bivalves and the female coral gall crabs become imprisoned
by surrounding coral growth with a small opening left for plankton and the
small male for reproduction
Arthropoda
•*Most crabs
are scavengers although terrestrial ones can eat plant material.
•
•Economically
the crustaceans are important as a food source for man and as plankton for the
organisms of the sea. Crayfish--over a million pounds a year are caught and
another 2 million reared artificially.
Arthropoda
•*Horseshoe
crabs and Sea Spiders..Chelicerated
Arthropods...no jaws, no antennae
•CLASS
MEROSTOMATA
•Chelicerated
Arthropods with abdominal gills and a long spikelike telson. The class contains Limulus the horseshoe crab and
fossil sea scorpions called eurypterids.
Arthropoda
•*This genus
appeared 175 million years ago and not undergone any evolutionary change since.
It also occupies a unique place in Arthropods. Like spiders it possesses
chelicerae, claws instead of chewing jaws, lacks antennae and has 6 pair of
appendages.
Arthropoda
•*Horseshoe
crabs or king crabs have a protective hinged carapace which covers the crab
with a long caudal spine protruding behind. There are compound eyes on the
carapace and median simple eyes. Beneath the carapace lie the chelicerae and 5
pairs of walking legs (comparable in evolution to the chelicerae, pedipalps and 4pr of walking legs in spiders.
Arthropoda
•*They live on
sandy or muddy bottoms in the sea, plowing their way through the upper surface
of the sediment. During burrowing, the spine levers the body down while the 5th
pair of walking legs acts as shovels.
Arthropoda
•*The carapace
form helps move through sand and the spine is used to right itself if it gets
turned over. They are scavenging carnivores and have jawlike
extensions on the bases of their walking legs used to trap and macerate prey
such as clams and worms before it passes to the mouth.
Arthropoda
•*The last
pair of legs use the bases to crack open bivalves. The appendages at the rear
are modified and each is expanded into 150 gill lamella resembling leaves of a
book and appendage movement maintains a current over the gills. Small horse shoe crabs can swim upside down using their gills as
paddles.
Arthropoda
•*
Reproduction occurs at night when they congregate in intertidal
zones, the female laying 2-300 eggs which get fertilized by the clasping male.
Eggs hatch into larva which mature in 3 years
Arthropoda
•*Class Pycnogonida
•500 species
about an inch long...except giant sea spider. The
abdomen is reduced to a knob. The intestines extend into the legs as well as
gonads located in legs. Between palps and 1st pair of
legs are an extra set of legs with which the male carries the eggs. It has 4
eyes near the anterior end of the animal and has no respiratory or excretory
system.
Arthropoda
•*Sea Spiders
are exclusively marine found in the intertidal zone and deep sea. They are able to grip the
substratum with their claws and sway from one individual to another They feed by either sucking up the preys body tissues or
cutting of pieces with their chelicerae and eating them.
Arthropoda
•*Colors are
usually white/transparent but red in the deep sea species. Economic importance
seems to be nothing.
Echinodermata
Phylum
Echinodermata...spiny skin because most members of
the group have defensive spines on the outside of their body.
They are found only in the sea and as adults are either attached or can crawl
around on the bottom. The 5 different groups include 1 sea lilies (attached)2. starfish, 3. brittle
stars, 4. sea urchins, 5. sea
cucumbers.
Echinodermata
*For
animals relatively high on the evolutionary scale, it is remarkable that a head
has never been developed.. Their weird symmetry is
called pentamerism, a form of radial symmetry with
the body arranged around the mouth.
Echinodermata
*This 5
point symmetry is displayed by most of the modern day echinoderms possibly
making a stronger skeletal framework, but their larva have bilateral symmetry.(so did their primitive ancestors).
Echinodermata
*The
skeleton is made up of many crystals of calcite (calcium carbonate). It
supports the body wall or test and the reinforced structure may be soft, sea
cucumbers or hard, sea urchins but is not a shell because it is covered by
living tissue (sand dollar).
Echinodermata
*The
drifting larva also has a skeleton which serve to support their delicate
swimming processes and another feature is their water vascular system
Echinodermata
*Water
Vascular System
The branched
tentacles, tube feet are arranged in a double row along the upper side of each
arm bounding a food groove and along the branched arms (pinnules).
The tube feet can be extended by hydraulic pressure from within the animal and
much of the water vascular system is internal.
Echinodermata
*They are
supplied with fluid from a radial water canal which runs down the center of
each arm just below the food groove and which sends a branch into each pinnule. The radial water canal of each arm connects with
that of its fellows via a circular canal running along the gullet of the
animal.
Echinodermata
*Pressure is
generated inside the system by the contractions of some of the tube feet and
also by special muscles in the canal itself which generate local pressure
increases to distend the neighboring tube feet.
Echinodermata
*The
activities of the tube feet relate to gas exchange and food gathering. The feet
are equipped with mucus glands and when a small fragment of drifting food
collides with one, the fragment sticks to the foot which flicks it to the food
groove and passes to the central mouth. The double rows ensure efficient
feeding..
Echinodermata
*Some
echinoderms also use the tube feet for locomotion (stars, urchins and
cucumbers).
Suckered tube
feet occur in all sea urchins and many sea cucumbers. Sea stars inhabiting hard
substrates also have these feet and use them for locomotion and catching prey.
Echinodermata
*The fluid
in the water vascular system is essentially sea water mixed with cellular and
organic material.
Apart from
driving the tube feet, the fluid is responsible for transporting food and wastes,
transporting CO2 and O2 and contains many cells,
Echinodermata
*amoeboid coelomocytes which play a role in excretion, wound healing,
and repair and regeneration.
No excretory
organs have been identified in echinoderms.
Echinodermata
*The
nervous system is strange, as there is no head or aggregation of nerve organs,
the only real sense organs are the rudimentary eyes of starfish, chemosensory
receptors of sea urchins, and balance organs(stratocysts)
in sea cucumbers, and that's it!
Echinodermata
*There are
simple receptor cells widely spread over the surface of the animal responsive
to touch and chemicals in solution. There is a nerve cord running down each arm
close to the radial canal and control the tube feet and body wall muscles.
Echinoderms are sensitive to gravity and respond when turned upside down.
Echinodermata
*Prey The common European star feeds on mussels and oysters while
the crown of thorn is well known for its selection of certain reef building
coral. Some burrowing stars ingest their prey whole while invert their stomachs
into the prey and digest it within the bivalve. ..Explain how it pulls open
prey.
Description
of Crinoidea (feather stars)
These
echinoderms have long, branched arms and a regular arrangement of small side appendages
that are known as pinnules. For mobility, sea lilies
are sessile and are limited to bending movements of the stalk and flexion and
extension of the arms. The stalkless comatulids can
move freely, being able to swim and crawl.
In terms of
habitats, crinoids prefer the tropics in coral reefs, in marine environments.
Some species live in cooler temperate waters among rocky reef and seaweed.
These creatures tend to be inconspicuous during the day and fully display
themselves at night to feed.
In the food
chain, crinoids feed by trapping small planktonic
organisms using modified tube feet. This food is passed down the crinoid's arms
in mucus strings along a ciliated food groove that leads to the mouth
Echinodermata
*Sea
urchins browse on algae on the surface and irregular urchins, sand dollars are
more specialized and live partially buried in the sand using modified spines
and tube feet to collect particles of detritus for food.
Echinodermata
*Sea
cucumbers use their specialized tube feet around the mouth and sweep the
surface of the mud for detritus.
Sexes are
separate with a few being hermaphrodite, passing through a male stage before
becoming functional females
Chordata
*Phylum Chordata
These are
higher animals possessing a single hollow, dorsal nerve cord and body cavity
(vertebrates, ) However a number of lowly chordates
display the phylums characteristics and are aquatic.
The two sub-phlya are Urochordata
(sea squirts) and Cephalochordata( lancelets).
Chordata
*Sea squirts
are bottom dwellers growing attached to rocks or other organisms, and are
encased in a thick protective tunic composed of a kind of cellulose or tunic
(thus Lamarck's name, tunicate). The tubular heart
pulses first in 1 direction and then in an opposite direction, changing every
few minutes.
Chordata
*At the
top is the inhalant siphon and on the side the exhalant siphon. There is no
head. Water is pumped through the body, the gill collecting respiratory material
and acts like a filter for food particles.
Chordata
*Wastes
are liberated from the anus near the external siphon. They may be solitary or
colonial. Larva have an important role in selecting a
settlement point and distributes the species. It is also the larva which
displays the chordate notocord characteristic.
Chordata
*Economically
they are important as fouling organisms as well as evolutionary and zoological
interest. They are the 1st animals in which alternation of generations was
discovered.
Chordata
*Another
interesting, but unproven theory, (no fossils), is that vertebrates arose from
tunicate tadpoles swimming up rivers where they could exploit the rich organic
detritus coming down the river after the freshwater and land plants had become
established.
Chordata
*In such
an environment the development of a backbone to aid in swimming would confer a
great advantage. A mutation which produced NEOTENY (attaining sexual maturity
in the larval stage) would eliminate the sessile adult.
Chordata
*Three
classes occur...Ascidiacea are sessile, living singly
or in complex colonial aggregations attached to submerged rocks, wharfs, ships
etc. Some resemble black, velvety bananas, others are rounded and pink called
sea peaches, others look like scarlet thumbs while others have the appearance
of gnarled potatoes.
Chordata
•One
species, Botryllus, grows as a glistening black or
purple mat studded with rosettes of yellow and pink openings like the petals of
a flower.
Chordata
*The
second class is Thaliacea comprising pelagic, usually
glass clear animals, more or less barrel shaped. The third class
the Larvacea are minute animals with long
tails.
Chordata
*Lancelets
have an elongated fish like blade form and the notocord
extended into the head. There is no well developed brain, eyes or other sense
organs. The adults live in shallow water inshore and are commonly burrowers.
11
Bivalvia
12. Cephalopoda.
13. muscles.
14. pearls
15. collect food as well as O2
16. gastropod
17 food
particles
c 18.
d 19
c 20.
A21.
e 22.
b 23.
e 24.
25-30 on your own!
\
c 37. Crustacea
a 38. Merostomata
b 39. Pycnogonida
40. lancelet
41. Crustacea
42. on beaches usually under decaying seaweed
43 Pentamerous Radial Symmetry
44Sea cucumber
45. Water vascular
system
46
Chordata
47. Urochordata
48. Tunicates
49. they flip their stomach
inside out and extrude it into a clamshell, digesting the meat externally
50. " spiny skin
51. nauplius larva
52. cypris larva
53.
leverage
54 Chaetognatha
55
copepods.
All
False---Make them true!
f
56. Radial symmetry in starfish indicates that they are among the most
primitive animal groups
b57. Echinoderms have an
exoskeleton composed of chitin
f 58 Echinoderms have a separate brain for each
portion of the radial body.
b 59 Molluscs and annelids produce similar planktonic
larvae called trochophores.
B 60
The Portugese man-of-war is a type of scyphozoan
cnidarian with a gas float.