c hapter 9 mollusks

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  • 1. Phylum Mollusca Class: Gastropoda Class: BivalviaClass: Cephalopoda
  • 2. Class GastropodaSnails, Limpets and Slugs
  • 3. General Body Plan: Gastropod Characteristics 1. Head foot Head: sensory nerves, mouth Foot: attachment and locomotion
  • 4. General Body Plan: Gastropod2. Visceral Mass Organs of digestion Circulation Reproduction Excretion Dorsal to the head foot
  • 5. General Body Plan: Gastropod3. Mantle (shell) Attached to visceral mass Encloses most of the body Protection4. Mantle Cavity: Gas exchange Elimination of digestive wastes Release of reproductive products
  • 6. That slimy foot Snail Slime: Escape Movement Water Retention Ecological Roles: Skin regenerating used in skin beauty products http://www.youtube.com/watc h?v=JhRwcPRy6l4&safety_ mode=true&persist_safety_ mode=1&safe=active
  • 7. Respiration One Gill in mantle cavity Oxygen is taken in Diffused through the cells Open Circulatory System Pushes blood in to expand Pulls it out to contract
  • 8. Digestion Scrape algae Enzymes break down food in stomach Radula: Scraping mouth Chitinous belt & curved teeth Covers fleshy tongue Muscles move it back and forth Conveyor belt
  • 9. Torsion Benefits Head enters first: protection Operculum seals opening to prevent drying out Allows clean water to enter mantle cavity Makes snail more sensitive to stimuli coming from the front
  • 10. Reproduction Monoecious: can be whatever sex they want! Internal cross fertilization One snail acts as female one acts as male Deposit eggs in gelationous strings
  • 11. Class BivalviaClams, Oysters, Mussles, Scallop s
  • 12. Structure Two halves of a shell: Valves Adductor muscles hold valves shut Visceral Mass Mantel Cavity Gills Cilia Siphon: filters water in and out of shell
  • 13. Foot Attach mollusk to surface Act as a lure to attract prey Surround organs for safety
  • 14. Ecological Roles Edible Commercial value: Form Pearls Valuable in removing bacteria from polluted water! Rely on water currents to get food Filter in nutrients, filter out clean water Valuable food source: humans, raccoons, otter s, birds
  • 15. Digestive System Food comes in through gills Sorted Digested Waste forcibly pushed out of mantle cavity by valves shutting quickly
  • 16. Respiratory System Respiration: Cilia in gills move water into mantel cavity Water tubes exchange water to blood through diffusion Water exits bivalve
  • 17. Human Interaction Many, many mollusks are threatened or endangered Over harvesting Pollution Loss of habitat Loss of water currents
  • 18. Mollusks: Cephalopods Octopus, Squid, Cuttlefish
  • 19. Physical Characteristics Anterior Tentacles and jet propulsion Mantle (Shell) Nautilus: only cephalopod w external shell Fills it with gasses to help w buoyancy Squid: internal shell, helps with structure Octopus: NO SHELL
  • 20. Locomotion Jet like propulsion out of mantle Squid: uses it for catching prey Up to 25 mph! Octopus: escape method
  • 21. ECOLOGICAL ROLE Fierce Predators Large brains Complex sensory structures Rapid locomotion Grasping tentacles http://www.youtube.com/watch?v=p9A- oxUMAy8&safety_mode=true&persist_saf ety_mode=1&safe=active
  • 22. Digestion Enzymes digest food in stomach Moves to anus Expelled during jet propulsion
  • 23. Giant Squid Dissection http://www.youtube.com/watch?v=d83n SFEoz2A&safety_mode=true&persist_s afety_mode=1&safe=active
  • 24. Predator Adaptations Locate prey by sight capture prey w tentacles/ suction cups Tentacles reinforced w protein Eat using a radula Cuttlefish: small invertebrates Octopus: Nocturnal: snails, fish, crustations
  • 25. Predator Adaptations Chromatophores Cells that can change colors Tiny muscles contract or expand and chromatophores quickly change color Alarm response Defensive Blend in w environment Courtship Bioluminescence http://www.youtube.com/watch?v=t- LTWFnGmeg&feature=related&safe ty_mode=true&persist_safety_mod e=1&safe=active