1. Stage 8: Deuterstomes
Phyla Echinodermata

2. A. The Seastars
1. These animals… a. have a mouth that develops after the anus. b. have a pattern of radial cleavage when the embryonic cells divide and are modified radial as adults. c. develop an endoskeleton. 2. Taxonomy a. Phylum Echinodermata “echino” = spiny, “derm” = skin b. Classes: (1) Asteroidea (sea stars) (2) Ophiuroidea (brittle stars) (3) Echinodea (urchins) (4) Holothuroidea (sea cucumbers) (5) Crinoidea (sea lilies)

3. Sea Cucumbers Sea Lilies / Feather Stars
Seastars Brittle Stars Sea Urchins
Sea Cucumbers Sea Lilies / Feather Stars

4. B. Structure and Function
1. Plate of calcium carbonate project through the skin (endoskeleton). 2. Water vascular system a. Fluid-filled system of interconnected canals. b. Primarily used for locomotion and feeding. 3. External Organization a. “Top” = Aboral (Not Dorsal) b. “Bottom” = Oral (Not Ventral)

5. 4. Internal Organization
a. Many echinoderms are pentameral: they have five-fold symmetry.
b. Appendages radiate out from a central disk that contains structures previously seen in the thorax and abdomen.
c. All structures found in one section will be found in the other four. These sections will regenerate if lost or damaged.

6. C. Niche 1. Predators of other invertebrates.
2. Rarely preyed upon (too tough to eat).
3. Sea cucumbers produce a toxin
(holothurin) that suppresses tumor
growth.

7. D. Showcase System: Endocrine
1. The glands of the body that produce enzymes to speed up the chemical reactions (metabolic catalysts).
2. Glands are primarily found connected to the digestive, excretory and reproductive systems.
Watch a seastar feed…

8. E. Strange but true!
When scared, sea cucumbers puke up their stomachs and release sticky tubules from their anus.
The stuff tastes bad and confuses predators. (Don’t worry, they’ll regenerate more!)