Class Asteroidea: Sea Stars• Aster = star, oides = in the form of• Large Coelome• Circulatory system: – use diffusion & cilia to move gas, nutrients and waste• Respiratory system: – Dermal branchi on skin
Asteroidea• Digestive System: – Mouth on underside – Opens into cardiac stomach • Folds out of body into prey to secrete enzymes – Opens into the pyloric system • Nutrients diffuse out of the pyloric stomach• Eat: – mollusks, crustacheans, polychaetes, coral, detritus
The Water Vascular System• Who can explain how hydraulics work?• Water Vascular System: – Made up of a series of water-filled canals that run down the arms from a canal ring in the center • Radial canal – ampullae – tubed feet
Asteroidea vs. Ophiuroidea• Sea Star vs. Brittle Star• Sea Stars: – Arms attached to arms – Carnivores: Active Predators• Brittle Star – Arms NOT attached to arms – Not active predators: eat plankton
Echinoidea: Sea Urchins• Same structure, longer spines than starfish – Move by means of tube feet• Feeding – Herbivores, feed on algae and marine plants – Grazers – Scrape food using ARISTOTLES LANTERN!• Roles: – Control algae
Sea Cucumbers• Elongated Body Plan – Long sea urchin• Tube feet to move• Separate sexes• Take organic nutrients out of sand – Use oral tentacles• Defense: – release internal organs – Tubules called cuvierian tubules: sticky and poisonous
CFU• What is the etymology of Echinoderm• What is the organ called that extends and contracts echinoderm’s tube feet?• What kind of symmetry are Echinoderms?• What is a major difference between the feeding habits of starfish and sea urchins?• What is the major difference between sea stars and brittle stars• Explain how sea cucumbers defend themselves. Why are they able to do this?