1. Echinoderms
Section 29.1

2. Animal Classification
Sponges
Cnidarians
Worms
Mollusks
Arthropods
Enchinoderms
Invertebrates
Echinoderms
Animals
Fishes
Amphibians
Reptiles
Ectotherms
(cold-blooded)
Vertebrates
Birds
Mammals
Endotherms
(warm-blooded)

3. What is an Echinoderm? Echinoderm (Greek word)
“echinos” – spiny
“derma” – skin
Rays – long, tapering arms that are covered with short, rounded spines

4. What is an Echinoderm?
Pedicellariae (PEH dih sih LAHR ee ee) – modified spines into pincerlike appendages
Echinoderms have radial symmetry

5. Water Vascular System
Water vascular system – a hydraulic system that operates under water pressure
Water enters and leaves the water vascular system of a sea star through the madreporite

6. Water Vascular System
Madreporite (mah druh POHR ite) – a sievelike, disk-shaped opening on the upper surface of an echinoderm’s body

7. Water Vascular System
Tube feet – hollow, thin-walled tubes that end in a suction cup
Tube feet look somewhat like miniature droppers

8. Water Vascular System
Ampulla – the round, muscular structure works like the bulb of a dropper
Tube feet also function in gas exchange and excretion

10. Varied Nutrition Sea stars are carnivorous and prey on worms and clams
Brittle stars and sea cucumbers feed on dead and decaying matter that drifts down to the ocean floor

11. Simple Nervous System
Echinoderms have no head or brain, but they do have a central nerve ring
Each radial nerve branches into a nerve net that provides sensory information to the animal

12. Simple Nervous System
Sea stars have eyespots located at the tip of each arm

13. Diversity of Echinoderms
Sea stars
Most species of sea stars have five rays, but some can have up to 40 rays

14. Diversity of Echinoderms
Brittle stars
Brittle stars are extremely fragile
This adaptation helps the brittle star to distract a predator

15. Diversity of Echinoderms
Sea urchins
Globe-shaped
Do not have rays
Look like pin cushions
Sand dollars
Disk-shaped
Do not have rays
A living sand dollar is covered with hair-like spines

16. Diversity of Echinoderms
Sea cucumbers
When threatened, they may expel their organs (intestines) through the anus
The organs may rupture and is regenerated in a few weeks