Echinoderms

1. Echinoderms Chapter 16

2. Phylum Echinodermata Phylum Echinodermata 400-million years old 12-18 classes have gone extinct Sea stars, sea urchins, sand dollars, and sea cucumbers

3. Phylum Echinodermata Characteristics 7,000 species All are marine Most are pentaradial, but some have reverted back to bilateral symmetry

4. Phylum Echinodermata Calcareous endoskeleton Series of ossicles or calcium carbonate plates May be the reason for pentaradial symmetry

5. Phylum Echinodermata Water-vascular system A series of water-filled canals Tube feet - extension of the water vascular system Usually has a suction cup at the end

6. Phylum Echinodermata Ring canal Five branches come from this canal Opening is called the madreporite Brings water in or out for water loss or to equalize pressure Tiedeman bodies and Pollian vessicles

7. Phylum Echinodermata Tube Feet Extension of the canal system Suction cup externally Ampulla Is a pump like structure that forces water into the tube feet

8. Phylum Echinodermata Complete digestive tract Complete nervous system Contains nerve net, nerve ring, and radial nerves

9. Phylum Echinodermata Hemal system Strands of tissue that encircle the echinoderm These strands use cilia to circulate fluid

10. Class Asteroidea Class Asteroidea 1,500 species Sea stars or starfish Eat snails, bivalves, crustaceans, polychaetes, corals, and others.

11. Class Asteroidea Many sea stars digest their prey whole Some pry open bivalves Once the bivalve is open 0.1 mm digestion begins Pyloric ceca

12. Class Asteroidea Regeneration Can regenerate any part of a broken arm Some can regenerate an entire sea star Dioecious External fertilization Embryos are planktonic Goes through two larval stages before metamorphosis

13. Class Concentricycloidea Class Concentricycloidea Sea daisies Highly modified member of Astroidea Lack arms < 1 cm in diameter Lack internal digestion

14. Class Ophiuroidea Class Ophiuroidea Brittle and basket stars > 2,000 species Tube feet do not contain suction disks Madreporite is located on the mouth

15. Class Ophiuroidea Water-vascular system is not used for locomotion Very flexible compared to starfish Snake-like arms are used to wrap around objects

16. Class Ophiuroidea Predators and scavengers No intestine, short digestive tract Bursae release nitrogenous waste through the tube feet Autotomy - used for defense arms fall off Dioecious

17. Class Echinoidea Class Echinoidea Sea urchins, sand dollars, and heart urchins 1,000 species All marine environments

18. Class Echinoidea Sea Urchins Sea urchins live in crevices Rounded in shape Skeleton is called a test Ten sets of plates Pedicellariae � contains two to three jaws Some contain venom which can also be injected into the predator

19. Class Echinoidea Types of Pedicellariae Forceps type (A), Scissors type (B, C), Tridactyl (B, D), Globiferous (E)

22. Class Echinoidea Oral end faces toward the surface Eat algae, bryozoans, coral polyps, and dead animals Aristotle�s Lantern is used for chewing

23. Class Echinoidea Sand dollars Burrow under the sand Dioecious External fertilization Larvae live in plankton

24. Echinoderms Echinoderm larvae Asteroids (A, B), Ophiuroids (C), Echinoids (D), Holothuroids (E), Crinoids (F)

25. Class Holothuroidea Class Holothuroidea 1,500 species Sea cucumbers All depths and all oceans

26. Class Holothuroidea No arms Elongated body Tube feet or tentacles surround the mouth Arrangement of 10-30 tube feet Range in size from 10-30 cm

27. Class Holothuroidea Thick body wall with no spines Move by worm-like crawling, some swim Respiratory trees circulate water and nitrogenous waste Madreporite is internal

28. Class Holothuroidea Many defense mechanisms Body wall toxins Everting tubules of respiratory tree (Cuverian tubules) Evisceration Dioecious External Fertilization Planktonic larvae

30. Class Crinoidea Class Crinoidea Sea lilies and feather stars 630 species Most ancient of echinoderms

31. Class Crinoidea Sea lilies attach permanently to the substrate Attached segment bears projections called cirri Unattached end is called the crown Feather stars swim and crawl

32. Class Crinoidea Suspension feeders Lack nerve ring Most are dioecious, but some are monoecious Protandry Regeneration can occur