2. Echinoderms: Main Characteristics
⢠Spiny Skin
â Endoskeleton
â Musculoskeletal
⢠5 part radial symmetry
â Penta-radial
â What was the advantage of
radial symmetry
⢠Tube feet: Movement
â Water-vascular system
⢠Benthic organisms
5. Class Asteroidea: Sea Stars
⢠Aster = star, oides = in
the form of
⢠Large Coelome
⢠Circulatory system:
â use diffusion & cilia to
move gas, nutrients and
waste
⢠Respiratory system:
â Dermal branchi on skin
7. Asteroidea
⢠Digestive System:
â Mouth on underside
â Opens into cardiac
stomach
⢠Folds out of body into prey
to secrete enzymes
â Opens into the pyloric
system
⢠Nutrients diffuse out of the
pyloric stomach
⢠Eat:
â mollusks, crustaceans,
polychaetes, coral, detritus
8.
9. The Water Vascular System
⢠Who can explain how hydraulics work?
⢠Water Vascular System:
â Made up of a series of water-filled canals that run
down the arms from a canal ring in the center
⢠Radial canal â ampullae â tubed feet
11. Asteroidea vs. Ophiuroidea
⢠Sea Star vs. Brittle Star
â Both can regenerate
arms
⢠Sea Stars:
â Arms attached to arms
â Carnivores: Active
Predators
⢠Brittle Star
â Arms NOT attached to
arms
â Not active predators: eat
plankton
12. Echinoidea: Sea Urchins
⢠Same structure, longer
spines than starfish
â Move by means of tube
feet
⢠Feeding
â Herbivores, feed on
algae and marine plants
â Grazers
â Scrape food
⢠Roles:
â Control algae
13. Sea Cucumbers
⢠Elongated Body Plan
â Long sea urchin
⢠Tube feet to move
⢠Separate sexes
⢠Take organic nutrients out
of sand
â Use oral tentacles
⢠Defense:
â release internal organs
â Tubules called cuvierian
tubules: sticky and
poisonous