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Mollusks%20bivalves%3agastro[1]

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  • 1. Phylum Mollusca Class: Gastropoda Class: Bivalvia
  • 2. Characteristics of Mollusca• Protosome characteristics• Coelom surrounds heart• Open circulatory system (except cephalopods)
  • 3. Class GastropodaSnails, Limpets and Slugs
  • 4. Gastropoda• Planning on being rich and famous?• Wining and dining at the most expensive restaurants?• Romantic trips to Paris?• Ever wonder what Ceaser munched on after long hard days ruling the roman empire?• Than you should be familiar with ESCARGOT!!!!
  • 5. General Body Plan: Gastropod• 1. Head foot• Head: sensory nerves, mouth – Anterior: near the head/mouth• Foot: attachment and locomotion – Posterior: near the anus – Flattened w Cilia: locomotion
  • 6. That slimy foot…• Snail Slime: – Suction power: travel up and down trees – Escape: Emit a nasty tasting slime when threatened – Movement: Allows them to easily squeeze through tight spaces – Water Retention• Ecological Roles: – Skin regenerating – used in skin beauty products
  • 7. General Body Plan: Gastropod• 2. Visceral Mass – Organs of digestion – Circulation – Reproduction – Excretion – Dorsal to the head foot
  • 8. General Body Plan: Gastropod• Mantle (shell) – Attached to visceral mass • Encloses most of the body – Protection• Mantle Cavity: – Gas exchange – Elimination of digestive wastes – Release of reproductive products
  • 9. 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
  • 10. General Body Plan: Mollusca• Radula: Scraping mouth – Chitinous belt & curved teeth • Covers fleshy tongue • Muscles move it back and forth • Conveyor belt• Digestion – Scrape algae – Enzymes break down food in stomach
  • 11. • How do mollusks exchange gasses – Filter air through their gills• Where are these gills located? – The mantel• What is the structure called that scrapes up food? – A Radula• All mollusks have: – A visceral Mass – A head foot – A mantel
  • 12. Gastropoda• Marine, Freshwater, Terrestrial• Signifying feature: Torsion
  • 13. 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
  • 14. Torsion
  • 15. 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
  • 16. CFU• What is Torsion? – The 180 degree twisting of internal organs in snails• How is Torsion adaptive? – Pulls head in first, seals opening, locates all sensory nerves in the front
  • 17. Class BivalviaClams, Oysters, Mussles, Scallop s
  • 18. Bivalvia!• 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
  • 19. 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
  • 20. Foot• Most mollusks have foot that can be used differently – Attach mollusk to surface – Act as a lure to attract prey – Surround organs for safety
  • 21. Respiratory System• Respiration: Cilia in gills move water into mantel cavity – Water tubes exchange water to blood through diffusion – Water exits bivalve
  • 22. Digestive System• Food comes in through gills – Sorted – Digested – Waste forcibly pushed out of mantel cavity by valves shutting quickly
  • 23. Human Interaction• Many, many mollusks are threatened or endangered – Over harvesting – Pollution – Loss of habitat – Loss of water currents
  • 24. CFU• What is the technical term for the two halves of the shell? – Valves• What structure filters water in and out of the shell – Siphon• What is the function of the foot – Attach mollusk to substrate, act as lure• Why are bivalves important to humans? – Pearls, food source, pollution filter• How are humans affecting bivalves? – Over harvesting, pollution, loss of current
  • 25. Get ready for dissection!