1. Class Asteroidea Pedicellariae
Tiny pincher-like organs on the aboral side keep the surface clean
Most sea stars are predators of bivalves, snails, or other attached or slow moving animals

2. Class Ophiuroidea Includes: Brittle Stars
Legs proportionally longer and thinner than sea stars
Allows for better movement
Organs in central disc
Tube feet lack suckers

3. Class Ophiuroidea
Eat organic matter and small animals they find on the bottom

4. Class Echinoidea Includes: Sea Urchins & Sand Dollars
Body structure forms a round, rigid body with movable spines and pedicellariae
Locomotion achieved by movable spines

5. Class Echinoidea
Body plan of sea stars repeated by moving arms upward and connecting them at the tips
Mouth is on the bottom, anus on the top
Spines: sharp, hollow and sometime contain venom

6. Plates:
10 plates
Alternating abulacral (have openings for tube feet) and interambulacral (bumps for spines)

7. Class Echinoidea
The mouth has an intricate system of jaws and muscles called Aristotle’s Lantern
Used to bite off algae and other bits of food from the bottom

8. Class Echinoidea
Heart Urchins and Sand Dollars are adapted for the soft bottom of the ocean
Flat bodies and short spines

10. Class Holothuroidea Sea Cucumbers
Similar body plan to a sea urchin, just stretched out from mouth to anus
Lies on sides, oral and aboral surfaces are at the ends

11. Class Holothuroidea
Most have five rows of tube foot that run mouth to anus
Some excrete toxic substance as defense mechanism
Some expulse gut and other internal organs out of the mouth or anus, called evisceration
Believe that they grow the organs back