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  1. 1. Echinoderms “spiny skin”
  2. 2. Echinoderms: Main Characteristics• Spiny Skin – Endoskeleton – Musculoskeletal• 5 part radial symmetry – Penta-radial – What was the advantage of radial symmetry• Tube feet: Movement – Water-vascular system• Benthic organisms
  3. 3. Classes• Asteroidea: Sea Stars• Ophiuroidea: brittle stars• Echinoidea: sea urchins and sand dollars• Holothuroidea: Sea cucumbers• Crinoidea: Sea Lilies and feather stars
  4. 4. 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
  5. 5. Diagram the arm of the starfish
  6. 6. 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, crustaceans, polychaetes, coral, detritus
  7. 7. 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
  8. 8. Water Vascular System
  9. 9. Asteroidea vs. Ophiuroidea• Sea Star vs. Brittle Star – Both can regenerate arms• Sea Stars: – Arms attached to arms – Carnivores: Active Predators• Brittle Star – Arms NOT attached to arms – Not active predators: eat plankton
  10. 10. 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• Roles: – Control algae
  11. 11. 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
  12. 12. Work on Study Packet