Phylum Echinodermata ...explanation..classification.... examples best of luck Stay happy

2. • Spiny skin.
• sea-star, sea-urchins, sea-cucumbers, sand
dollars, sea-lilies.
• Larval stage bilateral.
• Adult stage Pentaradial.
• Arms are movable appendages radiating
around central disk.

3. Larva with bilateral symmetry Adult with radial symmetry

4. Skeleton:
• Internal
• Mesodermal in origin.
• Consist ossicles covered by epidermis.
• Ossicles enclosing other tissues in flexible and
tough covering.

5. Water Vascular System
• Contains series of water filled canals which are
connected to tube feet.
• Main elements of water vascular system.
1.Ring canal.
2.Radial canals.
3.Lateral canals.
4.Madreporite.
5.Tube feet.
6.Hemal system.

6. • Ring canal have
1.Tiedmann Bodies produce coelomocytes.
2.Polian Vesicles a fluid storage sac.
• Canal system ends in to tube feet.
• Tube feet are for feeding locomotion,
respiration.
• Valves and suction cups present in tube feet.
• Hemal system strand of tissues, it transport
large molecules, hormones and coelomocytes.

9. Functions of Water Vascular System
Water vascular system perform many functions
in echinoderms like:
• Locomotion.
• Respiration.
• Attachment.
• Feeding.
• Exchange to environment.

10. • No excretory organs.
• No respiratory system.
• No well developed head.
• Poorly developed brain.
• Complete digestive tract.
• Ability to regenerate.
• Reproduced asexually and sexually.

11. Phylum echinodermata is divided into five
classes:
1. Class Asteroidea (sea stars).
2. Class Ophiuroidea (brittle star).
3. Class Echinoidea (sea urchin).
4. Class Holothuroidea (sea cucumber).
5. Class Crinoidea (sea lilies, feather stars).

12. Class Asteroidea
• Common member sea-stars.
• Mostly marine, may live in sandy/muddy area.
• Pentagonal/star-shaped body plan.
• Large coelome.
• Oral surface oriented downward.
• Aboral surface directed upward.

14. • Ossicles provide skeletal support.
• Between ossicles dermal branchiae present for gas
exchange.
• Pedicellariae is organ of defense.
• Ambulacral groove to capture food.
• Five groove present, one on each arm.
• Move in stepping motion.
• All feet move in one direction, under the control of
nervous system.
• Suction cups will maintain the position of animals.

15. • Sea stars feed on snails, crustaceans, corals.
• Complete gut system.
Stomach divided into two parts:
1. Large cardiac stomach.
2. Smaller pyloric stomach.
• Pyloric cecae helps in digestion.
• Gas exchange, nutrients metabolic waste transported
in coelome by ciliary movement of body cavity.
• Nerve ring and radial nerve present.
• Sensory receptors are on the body surface.
• They respond to light, chemicals, mechanical stimuli.

16. • Sea stars can reproduced asexually by
regeneration.
• Sexually,they are dioecious.
• External fertilization.
• Fertilized egg first develop into bipinnaria
larva.
• Then brachiolaria larva form with
development of arms.
• Larva are bilateral.
• Have bands of cilia for swimming.

17. • Larva undergoes metamorphosis and grows
into adult.
• Left side of larva become oral surface of adult,
and faces down.
• Right side become aboral surface, faces
upward.
• Larva settled to sea floor.
• Adapt adult radial symmetry.

19. Sea Daisy
• Unusual group.
• Tiny animals.
• Upper surface made of scales lined by spines.
• Lacks arms.
• No internal digestive system.
• Thin membrane Velum cover the outer surface,
through which nutrients absorbed & digested.
• Internal pouch to hold embryo during development.
• Free swimming larval stage absent.

20. Sea Daisy

21. Class Ophiuroidea
• Include basket star, brittle star.
• All are marine.
• Brittle stars have unbranched arms.
• Basket stars have branched arms.
• Dermal branches, pedicellariae absent.
• Tube feet lacks suction cups.
• Madreporite present on oral surface.
• Arms & tube feet used to sweep food to mouth.

22. • Mouth located in centre and surrounded by
five jaws for chewing.
• Mouth lead to stomach.
• No other digestive part extended into arms.
• Reduced coelome.
• Ammonia is primary waste product.

24. Basket Star

25. Class Echinoidea
• Includes sea-urchins, sand dollars, heart
urchins.
• May be round/heart shaped/flat.
• Body of sea-urchin covered by rigid shell
called test.
• Test is made of interlocking plates of calcium
carbonate.
• Test is lined by spines.

26. Sea urchin
Heart urchin
Sand dollar

27. • Spines are sharp, hollow, contain venom.
• Pedicellariae may contain venom sac, injected
into predators.
• Water vascular system similar to others.
• Tube feet has suction cups.
• Echinoids move by using tube feet and spines.
• Special chewing organ is Aristotle’s Lantern.
• It is feeding organ consisting of 35 ossicles
and muscles.

30. • Large coelome present.
• Small gills present.
• Gas exchange through gills.
• They are dioecious.
• Coelome filled with gametes during breeding
season.
• Fertilization external.
• Early development lead to larval stage.
• Larva undergo metamorphosis and develop
into adult.

31. Class Holothuroidea
• They are sea cucumber.
• Arms absent.
• Tube feet modified into tentacles.
• Body wall thick, lacks spines and pedicellaries.
• Ossicles embedded in dermis.
• Ossicles may be microscopic or large.
• Large ossicles form calcareous ring around oral end
of digestive tract.
• Ring serve as attachment organ.
• Madreporite is internal.

33. • Water vascular system filled with coelomic fluid.
• Ring canal, radial canal lateral canals and an
additional canals for tentacles.
• Tube feet have suction cups.
• Three rows of tube feet used for attachment.
• Two other rows are reduced/absent.

35. Sea cucumber

36. Class Crionoidea
• Sea lilies with long stalk.
• Unattached end is Crown.
• Aboral end of crown has calyx.
• Five arms attached to calyx.
• Arms are branched giving feather like
appearance.

38. • Arms supported by ossicles.
• Tube feet present along each arm.
• Feather-star lack stalk.
• They have cirri for attachment.
• Gas exchange & excretion similar to
echinoderms.
• Trap prey by tube feet.
• Nerve ring absent.

41. • Cup-shaped nervous mass below calyx, which
give radial nerve, that control the movement of
tube feet.
• Dioecious/monoecious.
• External fertilization.
• Metamorphosis occurs.
• Larval stage develop to adult stage.
• They reproduced asexually by regeneration