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C hapter 9 mollusks
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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• 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, Scallops
  • 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, otters, 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• 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• 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• LTWFnGmeg&feature=related&safe ty_mode=true&persist_safety_mod e=1&safe=active