1. Phylum Echinodermata

2. I. General Characteristics
Symmetry – Mostly Radial Sometimes Bilateral
Body has more than two cell layers, tissues and organs.
Eucoelomate
Deuterostome
Body shape varies
No head
Endoskeleton
Few Sense Organs

3. I. Nervous system - a circum-oesophageal ring.
J. Open circulatory system.
K. Has water vascular system, which hydraulically operates the tube feet or feeding tentacles.
L. Without excretory organs.
M. Normally possesses a epidermal system of calcareous plates
Reproduction –sexual; separate sexes;
external fertilization
O. Habitat - Marine Environments.

4. II. Classes of Echinodermata
Class Asteroidea
1. Have 5 arms usually
2. Mouth located in center of oral
surface pointing downward

5. 3. Has a Water Vascular System
a. Opening of the water vascular system the madreporite (=sieve plate)
b. Water enters the madreporite and goes through the stone canal to the ring canal
c. Water then passes through a radial canal extending into each arm
d. All along the length of these canals are lateral canals that terminate in a bulb- like structures called ampullae equipped with tube feet
e. Tube feet line the grooves on the oral surface - ambulacral grooves

7. 4. Has Mouth and Stomach
5. Has short intestine – extends from stomach
to anus.

8. 6. Endoskelton made up of calcareous plates. that penetrate the
6. Endoskelton made up of calcareous plates that penetrate the dermis as spines
7. Between the spines and plates are projections called papulae, which function in gas exchange and excretion
8. Other projections on the body wall include tiny jaw-like appendages called pedicellaria
9. Photoreceptors – respond to light
10. Examples: Starfish, Brittle stars

9. B. Class Ophiuroidea
1. Characteristics similar to class
Asteroidea
2. Main difference between starfish
and brittle stars is brittle stars
have much thinner arms.
3. Examples: Brittle stars

10. C. Class Echinoidea 2. Body is enclosed in a shell or test
1. No arms arms
2. Body is enclosed in a shell or test
3. Body surface is usually covered with moveable spines

11. 6. Use podia and spines during locomotion
4. Spherical body
5. Ambulacral plates bearing tube feet that radiate out toward the aboral surface
6. Use podia and spines during locomotion
7. The spines are moveable and articulate with the with the calcareous ossicles
8. Examples: Sea Urchins, Sand Dollars

12. 9. Feeding – Scrap algae off of rocks then
9. Feeding – Scrap algae off of rocks then using a chewing apparatus called Aristotle's lantern

13. 2. Endoskeleton is reduced to a few Ossicles on the surface
D. Class Holothuroidea
1. No arms
2. Endoskeleton is reduced
to a few Ossicles on the surface
3. Fairly soft-bodied
4. Locomotion – using
false feet and by
muscular contractions
5. Examples: Sea Cucumber

14. 6. Oral end of the body has a group of
6. Oral end of the body has a group of tentacles surrounding the mouth; used in feeding
7. Have a muscular cloaca that is partly used in gas exchange
8. Gas exchange
structures are
branching
structures
called
respiratory trees

15. E. Class Crinoidea 2. Oral surface is upward
1. Most primitive of echinoderms
2. Oral surface is upward
3. Has a stalk
4. Body portion attached to the stalk is the crown;
5. Has branches called pinnules
6. Ciliated around the mouth