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Unformatted text preview: 1 Phylum Mollusca Phylum Mollusca snails, clams, squids, octopus, chitons & friends 2nd largest phylum > 150,000 extant species > 50,000 fossil species 7 Extant Classes Aplacophora Aplacophora- worm-like, predators Monoplacophora Monoplacophora- resemble general moll. Polyplacophora Polyplacophora- chitons Gastropoda Gastropoda- snails, slugs Bivalvia Bivalvia- clams, oysters, scallops Cephalopoda Cephalopoda- squid, octopus Scaphopoda Scaphopoda- tusk shells Gastropoda Snails and slugs Shell coiled - derived - cap like, vestigial, lost Patellogastropoda True Limpets Radula made of iron and silica, docoglossan form (few large teeth), no operculum, free spawn, lecithotrophic eggs Vetigastropoda Slit shells, keyholes, abalone, top shells Free spawn, can have hole or slit in shell, radula with many teeth, usually chitin, eat bryzoans, sponges, derived - herbivores and detritivores Neritimorpha Marine, terrestrial and freshwater includes freshwater nerites - adults in freshwater, but veliger larvae must develop in sea water. Migrate up streams once metamorphosed. 2 Caenogastropoda Majority of gastropods, all feeding types and life styles, generally separate sexes, internal fertilization (copulation), all developmental types, typically coiled shells (exception - slipper shells, tube-shaped vermetids, etc.), some extreme modifications of the radula, many specialized. I ncludes Neogastropoda Derived predators Specializations for prey capture Monopectinate gills, specialized radulae (2 or 3 teeth / row), siphonal canal in shell, large osprahdium, concentrated nervous system, separate sexes, copulate, most direct development with benthic egg capsules, nurse eggs, crawl away juveniles Subdue prey by consuming whole (e.g., olives), breaking shells (i.e., channeled and knobbed whelks), drilling (e.g., oyster drill, moon snail, tritons), or by injecting toxins...
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- Fall '10