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Chapter 7

http://www.zsm.mwn.de/mol/e/. Chapter 7. ucmp.berkeley.edu. Xaxor.com. Phylum Mollusca Class Bivalvia Class Gastropoda Class Cephalopoda. seawater.no. ucmp.berkeley.edu. Phylum Mollusca. Characteristics: More than 200,000 species Name means "soft body ”

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Chapter 7

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  1. http://www.zsm.mwn.de/mol/e/ Chapter 7 ucmp.berkeley.edu Xaxor.com Phylum Mollusca Class Bivalvia Class Gastropoda Class Cephalopoda seawater.no ucmp.berkeley.edu

  2. Phylum Mollusca • Characteristics: • More than 200,000 species • Name means "soft body” • Basic body plan – head, muscular foot and visceral mass in most species home.sandiego.edu

  3. General Anatomy of Molluscs • Mantle- secretes shell, waste disposal, sensory reception, respiration • Many have a shell of calcium carbonate • Radula for grazing is unique to this group • Some are deposit feeders, others carnivores, some use radula for scraping algae, encrusting animals, etc. off substrates • Well developed nervous system • Open circulatory system • Complete digestive system • Sexual reproduction - trochophore larvae develops into a planktonic veliger larvae complete with shell (miniature version of adult)

  4. General Reproduction fao.org

  5. Class Polyplacophora • Chitons • 800 species • All marine • Dorsal shell of 8 plates • Ventral muscular foot • Ventral mouth with radula shells.tricity.wsu.edu

  6. Class Polyplacophora • Chitons • Mostly found in shallow water, coastal environments of hard substrate • Many graze on algae & small animals in marine intertidal zone (area between high and low tides)

  7. Class Bivalvia • Clams, oysters, scallops, mussels, etc. • Two shells or “valves” • Oldest part of the shell is called the umbo • Shell grows out from the umbo in concentric rings • No head present • No radula present • Adductor muscles secure valves together • Muscular foot used for burrowing in bottom and other locomotion • Water circulated with siphons • Gills for respiration & food gathering (filter feeding) • Some species burrow, others attach to hard substrates via byssal threads, or grow attached to each other

  8. Class Bivalvia

  9. Class Bivalvia • Italy’s Giant Mussels • Giant Clam • Geoduck Clams Byssal Threads

  10. Class Gastropoda

  11. Class Gastropoda • Largest class of molluscs, about 75,000 species • Name means "belly-footed” • Coiled shell on most species • No shell on sea slugs (nudibranchs) • Radula for grazing on plants in most, some are deposit feeders • Some species are carnivorous and use radula for prey capture (some will even prey on members of the same species) • Cone snail Berkley.edu

  12. A few Bahamian molluscs

  13. A few Bahamian molluscs Tide Pool Gastropods Coral Reef Flamingo Tongue

  14. Class Cephalopoda • Squid, octopus, nautilus, & cuttlefish • All 650 species marine • Fast swimming predators due to water jet propulsion • Well developed eyes • Thick mantle covers the body • Use beak-like jaws and radula to crush or rip prey • Adapted tentacles

  15. Class CephalopodaOctopuses

  16. Class Cephalopoda • Shell internal or absent in most • Most advanced invertebrates (smart octopus) • In octopus, the shell has been replaced by a beak-like jaw which can deliver a powerful bite • Some octopus have toxic bites • Ink sac is also seen in octopus to allow escape from predators • A stiff internal “pen” is seen in squid is a modified shell; cuttlebone in cuttlefish

  17. Class CephalopodaSquid and Cuttlefish

  18. Class Cephalopoda • How smart is an octopus?

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