Download Echinodermata

Echinodermata
- Are radially symmetric -not related to cnidarians,
because the bilaterally symmetic larval stage becomes
a radially symmetric organism. In this group, the
coelom forms three distinct spaces, found in all
deuterostomes including us. They are mobile but not
very fast.
Phylum Echinodermata
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!
Deuterostomia
!
(autapomorphies)
• Blastopore becomes the
anus
• Tripartite coelom
• Dipleurula larval stage
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Porifera
Placozoa
Cnidaria
Ctenophora
Platyhelminthes
Gastrotricha
Gnathostomulida
Cycliophora
Rotifera
Annelida
Mollusca
Sipuncula
Nemertea
Brachiopoda
Phoronida
Bryozoa
Arthropoda
Tardigrada
Onychophora
Nematomorpha
Nematoda
Priapulida
Kinorhyncha
Loricifera
Echinodermata
Hemichordata
Chordata
DEUSTEROSTOMIA
1- Blastopore becomes the anus:
2- Tripastite coelom: made of three separate coelomic
spaces: the anterior protocoel, the middle mesocoel and
the posterior metacoel. These 3 regions are often visible
as the : prosome, mesosome and metasome.
3- Dipleurula larval stage: an anscestral characteristic
for the deuterostomes.
- As you move up in specialiazition, you develop 2
epithelial layers (inner, out)- happened by
invagination, and the result is the 2 layers of the gut.
Blastopore (Gastrulation)
Ectoderm
Blastocoel
Endoderm
Blastopore
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Echinodermata
- In the deurostome line ALL of them have a
ENTEROCOELOUS COELOM- bubbles from the
gut expanded in the space in between
- Bryozoans have this, but are not deurostome.
- Blastopore becoming the mouth is not connected
with shizocoel.
Enterocoelous coelom
Ectoderm
Endoderm
Mesoderm
2135 Animal Form & Function
In BIO
deuterostomes,
the coelom typically forms
through enterocoelous development. In enterocoelous
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development,
the mesoderm of the gastrula forms as two outgrowths of the endoderm. As they grow
larger, the two mesodermal pouches grow toward each other. Eventually, they meet and merge. The
space between the mesodermal layers forms the embryonic coelom.
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Tripartite coelom
Mesocoel
Protocoel
Metacoel
Mouth
Anus
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- Proto, mesocoel and metacoel- bryozoans have this.
- In bryozoans the protocoel was reduced
-The tripartite coelom forms by enterocoelic
(Archenteric) pouching from the wall of the primitive
gut, the archenteron, which forms during gastrulation.
As the pouches pinch off from the gut and detach, they
are now mesodermal, and the opening in the centre
becomes the coelomic cavity. As its name suggests, the
still list thetripartite coelom is made of three separate
coelomic spaces: the anterior protocoel, the middle
mesocoel, and the posterior metacoel.
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- Ciliated band, for locomotion (propels the organism
fordward). Mouth in the middle
- The gastrula develops into a basic larval type called a
dipleurula larva, characterized by bilateral symmetry;
- This larvae undergoes metamorphosis to become
radially symmetrical
- characteristic larvae found in echinoderms
Dipleurula larva
Preoral lobe
Mouth
Ciliated band
Esophagous
Stomach
Anus
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ECHINODERMATA (sea stars)
Echinodermata
1)PENTARAMOUS SYMMETRY: radial symmetry based on 5s.
2)WATER VASCULAR SYSTEM: unique mechanism to move sea water into the body to use as a
hydrostatic skeleton to move their tube feet. The water in the system is the same as sea water plus
tideman's bodies which remove small Porifera
bacteria from water. No pumping system associated with W.V.S,
Placozoa
cilia around the walls slowly mix water
thorughout the system
Cnidaria
Ctenophora
Tube feet- locomotion, feeding, exchange surface for
Platyhelminthes
Gastrotricha
Gnathostomulida gases and nutrogenous wastes. Tube feet can be
Cycliophora
Spicule: needle like
hydrsotatically isolated fromthe rest of the system,
Rotifera
Annelida
structure
Mollusca
acting like a small hydrsotatic skeleton. Muscle
Sipuncula
Nemertea
contractions in the wall of the tube foot, and the
Brachiopoda
Phoronida
ampula, combined with suction cup action of the
Bryozoa
Arthropoda
podum allow each tube feet to pull the echinoderm
Tardigrada
! Echinodermata
Onychophora
along.
(Autapomorphies)
Nematomorpha
Nematoda
• Pentaramous symmetry
Priapulida
3)STEROM SPICULES: starfish secrete calcareous
• Stereom spicules
Kinorhyncha
• Water vascular system
Loricifera
secretions to make spongy spicules, and this forms the
! Echinodermata
• Mutable connective tissue
Hemichordata
Chordata
calcareous endoskeleton. These spicules is porous and
spongy. Spicules of calcite microcrystals formed from calcium carbonate are arranged in 3D hollow
arrays referred to as the stereom. Sclereocytes produce the original spicules
4) Mutable connective tissue:These spicules are connected with connective tissue, and the tissue that
holds it can change consistency (mechanical properties): from stiff to rigid and vice versa- this is under
Parazoa (1.2%)
Extantcontrol,
Animalia controls wether
nervous
Radiataits
(0.9%)loose or rigid NOT seen in anywhere in the word.
~1,300,000 species
Protostomia (3.9%)
Platyzoa (2.2%)
Platyhelminthes (1.9%)
Others (0.3%)
Lophotrochozoa (9.8%)
Mollusca (8.5%)
It is not a big group
-Not a lot of them because it returned
to be radially symmetric
Annelida (0.9%)
Others
(0.5%)
- There was a huge advantage to be
bilaterally
symmetric, this group took a step back
Ecdysozoa (82.0%)
Crustecea (3.1%)
Chelicerata (7.6%)
Atelocerata(70.3%)
Others (1.1%)
Deuterostomia (4.0%)
Chordata (3.5%)
Others (0.4%)
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Star fish
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Echinodermata
Sea urchins
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Sand dollars
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- drops its arm, and regenerates
Brittle stars
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Echinodermata
- slow movement. Defense themselves by throwing
his gut out, so the predator is happy because it has
food.
Sea cucumber
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Ancient Echinoderms
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-This group returned to radial symmetry- secret is in
the fossils
- When the echinoderms appeard they were sessile,
arms pointing up, with their tube feet up catching
debree that fell from water colum and moving it to the
mouth in the center. This made them sucessful at the
time, because they could feed on that debree, and the
animals at the bottom (mollucs, etc) could not get a
hold on that food. This was their advantage, and in
order to do this and be effective they had to be
radially symmetric
- most of them are not stationary, they move by their
tube feet.
- They were first sessile, arms extending from the
outside, mouth facing up, tube feet extending from the
arms, used to propel food towards the central mouth
wen food fell down. They still have this architecture
but most have turned themselves upsidedown.
-Radially symmetric animal dont have dorsal ventral,-have ABORAL AND ORAL.
- When the echinoderm becomes mobile they detach
from the substrate and flip the other way (mouth
poiting down), and tube feet are used to pull the
echinoderm across the susbtrate
Ancestral echinoderms
FOSSIL
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Echinodermata
- Hundreds of tube feet- part of water vascular
system. Filled with sea water
Echinoderm surfaces
Tube feet and
ambulacral
groove
Aboral surface
Oral surface
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- tube feet are hydrostatic skeletons used for
locomotion.
Water vascular system
(Ambulacral system)
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- Cirulatory system: sea water that circulates in the
tube feet as a transport fluid, to move o2, wastes..
- Tube feet are thin- large S.A to V ratio to use for gas
exchange.
- Use simple ammonia as a metabolic waste because
of the high surface to volume ratio of the tube feet.
- this system locks them into the marine environment
(no metanephridia, etcc) .
Role of the water vascular system




Locomotion
Circulation
Respiration
Excretion
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Echinodermata
Water vascular system
Madreporite
Stone canal
Ring canal
Tiedemann’s
bodies
Polian
vesicles
Radial canal
Lateral canal
Tube feet
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-external opening- MADREPORITE is where sea
water comes in (regulates the water)
- Tidemann body add few cells to the water that eat
bacteria and keep it healthy
- Water is not being pumped in/out- ITS JUST A
GIGANT PUDDLE OF WATER, theres cilia moving
water around, but not pumped. It is not a circulatory
system, it just a passive reservoir of water (exam
question)
- This system is NOT a circulatory system because
the excretory and circulatory systems was lot in this
group (AKA no heart or functional anus)- just a
passve system that is 100% reliant on sea water.
- Purely sea water (most part), some cells- tie demanns
bodies that help with bacteria
- tube feet extend down- there are miniature
hydrostatic skeleton with a suckition cup
- tube feet extend through the body wall. Ampulla at
the top, muscles contract in there to extend the foot.
Tube feet
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Tube foot
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Ampulla
Lateral canal
Body wall
Tube foot
Retractor
muscles
Podial muscle
Sucker
ANATOMY OF TUBEFEET
- valve shuts and becomes an isolated hydrostatic
skeleton.
-Reservoir at the top- the AMPULLA
-at the bottom there are muscles, and when they
contract they change the direction
-At the base of the foot, theres a sucker that pulls the
base up. This allows for the tube feet to suck into the
substrate
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Echinodermata
- tube feet constatly being lifted and attach againt to
the susbtrate to move and capture prey.
- Not fast
- All the start fish are carnivorous- they chase after
other animals, like corals, clams, and other start fish.
When feeding upon a clam, tube feet attatch to it and
opens the clam with its arms, inverts its stomach and
releases digestive enzymes than then drinks.
- These are social animals, they are are socializing at
a very slow speed.
Movement of tube feet
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- covered in spines and cilia that sweeps away any
debris on the surface.
Body wall
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- Pedicellaria- in the surface of star fish
-prevents other animals to settle in the surface of the
star fish. They do this because they need this side for
gas exchange.
- the whole outer surface of the organisms is covered
in cilia, creating water movement to flush animals
away.
Pedicellaria
Spine
Pedicellaria
Dermal
branchia
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-Dermalbranchia: on the aboral side, thse are small
projections on the body wall used for gas exchange.
- metacoel-made the water vascular system
-mesocoel- makes the body cavity.
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Echinodermata
Digestive system
Anus
Pyloric stomach
Cardiac stomach
Digestive gland
(Pyloric cecum)
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Sea star
Gonad
Anus
Pyloric stomach
Cardiac stomach
Mouth
Pyloric cecum
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- They have 2 pairs of glands that go into each arm.
-Pyloric cecae- digestive glands (where digestion
happens). Two digestive glands that extend to each
arm, here, there are big sacs that extend to each arm
where final digestion occurs.
- cardiac (outside) and pyloric stomach (inside).
- There is little waste, because food is very liquidly
and there is not hard waste so there is no functional
anus.
- When feeding the cardiac stomach can be
everted, wedged in btw of the crack of the clam, and
sends stomach inside. Releases digestive enzymes
inside the clam, and cilia causes a current to pull the
food into the stomach. Cilia carry it to the digestive
glands (pyloric cecum) to the digested.
- Food travels to the cardiac stomach, then to the pyloric
stomach and sends out to cecae , extended into both arms
-When this animal is reproductive, gonads poliferate,
expands and gonads then are sitting adjentitly to the
digestive gland. Digestive glands are within the arms
- cardiac stomach can be squeezed out, this is the major
way in how starfish feed.When starfish finds a meal,
turns the stomach insideout and digest the meal.
-Carnivorous- prey on corals and clams. Only predators
on animals that are sessile or move slower than them.
-type of digestion: extracorporal digestion. Spiders do
this.
Feeding
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Echinodermata
- Arms- digestive ceca, pyloric ceca, and gonads, and
tube feet.
Reproductive system
Gonad
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The metacoel creates the standard body cavity. Comes out as the little fingers of the dermal branchia.
Wraps around the ampulae of the tube feet, so theres 2 coelomic spaces re conneted to each other in
these of the emmbrane of the ampulae. So there is a big difussive surface, 2 coelomic cavities are all
involved in diffusive roles.
- Tube feet gets things from coelomic fluid, all of
them aer enlarged and SA is increased by dermal
branchia. Water vascular cavity is the mesocoel.
- Madreporite replenishes the sea water.
- The water vascular system prominent features are:
tube feet, ampulla, suction cups. This is the
metacoel
-The mesocoel, contains the digestive glands and
the gonads,
Sea star arm
Spine
Dermal branchia
Ossicle
Digestive gland
Coelom
Gonad
Tube foot
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- very long spines that helps them move across the
susbtrate
- Sea urchin fold all the fins upwards so that they
made a sphere there is one pore at the bottom.
- The starfish with oral side down and ambulacrual
groove and tube feet.
Echinoidea
Sea urchins
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Echinodermata
-Hervivore.
-Digestive track is lengthned.
- Digestive track is long because its a hervivore and
the food is poor in nutrients. So they keep the food
long enough to extract all the nutrients.
- inside: gigant digestive tract, and on top : gonads.
-5 pairs of gonads- food source, delicacy.
- same structures as starfish, but radial cannals are
projected upwards.
Echinoidea
Water vascular system
Madreporite
Axial organ
Ring canal
Radial canal
Tube feet
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- tube feet are long because have to extend along the
spines.
- Set of muscles tilt and tip the spines, coordinated by
the nervous system. It can crawl into a cavity and
spread its spines out and anchor them. Nothing can
pull it out to feed on.
Echinoid spines and pedicellaria
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FEEDING MECHANISM
- has 5 sets of little teeth, aligned with 5 row of tube
feet.
- In the very center of the membranoeus area is the
feedin strcuture. The tube feet are modified into
branched puffy structures called gills.
- Aristotles lantern
Echinoidea
Oral surface
“Gill”
Ambulacrum
Openings for
tube feet
Teeth of lantern
Peristomial
membrane
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Echinodermata
- Aristotle lantern: suspended by muscles that can push
the lantern up or back, or tilt. 5 pyramidal teeth that are
associated with the feeding apparatus can be pushes
back, in little spread apart and close (biting motions).
-the mouth is equipped with five teeth operated by a
complex system of plates and muscles called Aristotle’s
lantern.
Aristotle’s lantern
Epiphysis
Tooth
Pyramid
Lantern retractor
Lantern protractor
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- the pyramid part of the tooth has another tooth
inside of it. this little tooth does the cutting, and its
constantly regenerating.
- organism can process large amounts of plant material
Echinoidea
Aristotle’s
lantern
Tooth
Pyramid
Compass
Epiphysis
Dental sac that
forms tooth
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Echinoidea
Digestive system
Esophagus
Aboral intestine
Aristotle’s lantern
Siphon
Anus
Tube feet
Gonad
- Siphon:as the food enters into the oral intestine, water
is pulled out to concentrate the food to extract all the
nutrients.
-In the aboral intestine, water is put back into the
dehydrated food, so it doesnt tear the digestive tracktand now it can be excreted.
-aristotles lanthern shoves food into the intestine.
Spirals through the organism. Goes to the large
intestine.
Oral intestine
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(stomach)
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