1. Phylum Echinodermata Introduction

2. Echinodermata
About 6000 species, all marine

3. Echinodermata Major characteristics
secondary pentamerous radial symmetry internal skeleton
water vascular system

4. Water Vascular System Madreporite stone canal ring canal radial canal
lateral canals
Ampulae
tube feet

5. CLASSIFICATION OF ECHINODERMATA
Class Asteroidea
Class Ophiuroidea
Class Echinoidea
Class Holothuroidea
Class Crinoidea

6. Class Asteroidea True Starfishes

7. Class Asteroidea True Starfishes
arms not sharply delineated from central disc
tube feet with suckers; used for
Locomotion
obtaining food
madreporite and anus aborally located
some have pedicellariae - jawlike appendages of epidermis

8. Class Asteroidea True Starfishes
Feeding
Mouth
cardiac stomach- can be extruded
pyloric stomach
pyloric caecae
Anus
feed primarily on sessile organisms

9. Class Asteroidea Systems
Circulation
poorly developed with fluid filled chambers;
no heart; coelom ciliated for fluid movement
Excretion
no special organs
general diffusion across body surfaces like tube feet
Respiration
across body membranes
Nervous System
associated with epidermis
circular oral nerve ring with branches into arms

10. Asteroidea Body wall Epidermis- outer surface; includes mucous cells
epithelium
Pedicellariae- jawlike appendages of the epidermis
can open and close
used to clean body of debris or put debris on body
Dermis- includes
nerve cells
connective tissue
Skeleton- below dermis
made of ossicles
lattice like connections
Calcium carbonate
with spines and tubercles
Muscle layer- below dermis
Peritoneum that lines coelom

11. Asteroidea Reproduction
are dioecious; external fertilization
usually 10 gonads; 2 in each arm
have fissiparity- division of central disc into two animals

12. Asteroidea Reproduction
free living larvae
bipinnaria- first larval form develops into
brachiolaria - shows development of arms

13. Class Ophiuroidea Brittle Starfishes

14. Class Ophiuroidea Brittle Starfishes and Basket Stars
5 arms usually
central disc well marked off, no branches of gut in arms

15. Class Ophiuroidea Brittle Starfishes and Basket Stars
no anus, no ambulacral groove
madreporite on oral surface
no suckers on tube feet, no ampullae (have a valve to control pressure)
no pedicellariae
able to move quickly and snake like hence their class name

16. Class Echinoidea sea urchins, sea bisquits, sand dollars

17. Class Echinoidea no arms skeleton is fused into a solid test
tube feet have suckers
covered with moveable spines and pedicellariae

18. Class Echinoidea
specialized mouth structures - Aristotle's Lantern

19. Class Holothuroidea Sea cucumbers

20. Class Holothuroidea Sea cucumbers
body elongated in oral-aboral axis
skeletal system reduced or absent
no spines or pedicellariae
mouth and anus at opposite ends of body

21. Class Holothuroidea Sea cucumbers
no external madreporite
tube feet with suckers
respiration through anal respiratory tree
dioecious; single gonad
suspension or detritus feeders
commensal relationship with pearl fish

22. Class Crinoidea Sea Lillies

23. Class Crinoidea Sea Lillies
most are extinct
most primative
all sessile, with stalk that attaches to substrate
have branched arms for filter feeding
no suckers on tube feet
no madreporite
no pedicellariae