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Mollusca

Mollusca. Soft bodied animals. Mollusca General Info. 150,000 known species Most mollusks are marine, but some live in fresh water environments Mollusks are soft-bodied animals that are sometimes protected by a hard shell. Symmetry in Mollusca.

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Mollusca

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  1. Mollusca Soft bodied animals

  2. Mollusca General Info • 150,000 known species • Most mollusks are marine, but some live in fresh water environments • Mollusks are soft-bodied animals that are sometimes protected by a hard shell

  3. Symmetry in Mollusca • In the beginning of the life cycle of a mollusk, bilateral symmetry is present, but this may be lost by adulthood as they have spiral development

  4. Body Development in Mollusks • 3 main parts: muscular foot, a visceral mass, and a mantle • The muscular foot is used for movement • The visceral mass contains most of the internal organs • The mantle is a fold of tissue that secretes the shell if present, covers the visceral mass • The shell secreted by the mantle is made of CaCO3

  5. Movement • In Polyplacophora, Gastropoda, and Bivalvia, a muscular foot is used for locomotion • In Cephalopods, siphon made from the mantle allows jet propulsion

  6. Germ Layers and Coelom • Open circulatory system, where the body cavity is a blood-filled hemocoel filled with hemophyll (blood and lymph between organs)

  7. Life Cycle/Reproduction • Starts with a ciliated larva, otherwise known as a trochophore • No true segmentation unlike Annelids • Normal sexual reproduction is present, although some are hermaphrodites • Most have external fertilization

  8. Specialized Tissue • The radula is a tongue-like structure that scrapes up food and is modified into a beak in the octopus • The mantle cavity is a water-filled chamber that houses the gills, anus, and excretory pores • Torsion is a process in Gastropoda where one set of muscles grows faster than the other, which creates the shell to grow in a spiral pattern

  9. Chiton (Polyplacophora) Octopus (Cephalopoda) Snail (Gastropoda) Squid (Cephalopoda) Scallops (Bivalvia)

  10. http://www.youtube.com/watch?v=nHVoV0MVwSc nudibranch http://www.youtube.com/watch?v=zsScH4TJ7NA chiton http://www.youtube.com/watch?v=5oExwxkuT_c octopus camoflauge, beak, and feeding Mollusk behavior http://www.youtube.com/watch?v=9-azBDt0kik&feature=PlayList&p=EF6646ECD09DBAB3&index=0&playnext=1 flexible octopus body http://www.youtube.com/watch?v=T8cf7tPoN5o&feature=PlayList&p=EF6646ECD09DBAB3&index=1&playnext=2&playnext_from=PL octopus intelligence http://www.youtube.com/watch?v=k_coXZq05xY swimming clam http://www.youtube.com/watch?v=UUNsrkV_KIY&feature=related burrowing clam http://www.youtube.com/watch?v=XbOwjE8EkSw&feature=PlayList&p=859B17D0EA1926B2&playnext=1&index=2 chambered Nautilus

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