1. II. Echinoderms; Phylum name describes the spiny skin of the animals.
A. Adults have radial symmetry, but larvae are bilaterally symmetrical.
B. Echinoderms have an endoskeleton made of calcium.
1. The skeletal structure is made of plates are called ossicles, and are joined together by “catch connective tissue”
2. The catch connective tissue allows the animal to change, from flexible to stiff and rigid.

2. C. Water vascular system; operates by changes in water pressure.
1. allows an exchange of gases (CO2 and O2).
2. helps them capture food
3. excretes wastes
4. allows the animal to move
5. Works as a part of the circulatory system;
they have an open circulatory system

4. D. Reproduction is usually sexual, but in asteroidea
(sea stars) regeneration can produce a new individual.
E. Nervous systems vary greatly.
There is no head or brain, but there is a central nerve ring. Most do not have any sensory organs.
1. All can detect light and touch.
2. Sea stars have a sensory organ called an eyespot that is located at the tips of the rays.
They use the eyespot to detect light intensity.

5. F. Six Classes;
1. Sea stars- commonly called starfish.
a. Use the tube feet on their rays for locomotion
b. commonly feed on bivalve mollusks by pushing stomach through the mouth and partly digesting food outside the body.
c. usually regenerate damaged rays
2. brittle stars-
a. do not use tube feet for locomotion, but slither on flexible rays.
b. rays are easily broken off, but will regenerate.

9. 3. sea urchins and sand dollars
a. do not have rays.
b. have very small tube feet
4. sea cucumbers
a. locomotion occurs because of combined use of tube feet and muscle action.
b. defense- expulsion of internal organs, which will later be regenerated.

14. 5. sea lilies and feather stars
a. mobility-
*sea lilies are sessile.
* feather stars are sessile in their larval state, but use their feathery arms to swim, as an adult.
6. sea daisies
a. tube feet are located along the outside edge of their disk shaped body.
b. Only 2 species currently known.

15. ← Sea Lily
Feather Star ↓