14. Mollusca III Oct 19

14. Mollusca III Oct 19 - Phylum Mollusca snails, clams,...

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1 Phylum Mollusca Phylum Mollusca 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 - chitons Gastropoda Gastropoda - snails, slugs Bivalvia Bivalvia - clams, oysters, scallops Cephalopoda - squid, octopus Scaphopoda Scaphopoda - tusk shells Gastropoda Snails and slugs Shell coiled - derived - cap like, vestigial, lost vestigial lost cap-shaped shell Shells Coiled some features phylogenetic other convergent Know parts of shell, including opercula, described in lab text and hand out. Identify these parts and types of coiling.
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Secreted by Mantle Secreted by Mantle Multilayered periostracum - outer organic covering prismatic - middle, crystalline, calcite nacreous - inner, sheet like crystal calcite Mantle secretes, repairs shell covers viscera Mantle Cavity external mantle lined space with gills = ctenidia ducts Ctenidia - Physiological role - respiration Morphological role - divide mantle cavity inhalant and exhalent area See in your dissections Primitively - bipectinate, axis carries afferent blood vessel (leaving heart) Stiffened with skeletal rod Perpendicular to axis Perpendicular to axis - Filaments or Lamellae Filaments or Lamellae Primitive - 2 bipectinate Lose one Monopectinate Circulatory System Heart Arteries Haemocoel Transport Oxygen, nutrients, waste Hydrostatic Skeleton body support extend tentacles antagonize muscles Body Axis Torsion Torsion - 180º Counter clockwise rotation of viscera relative to the in Veliger larva Asymmetries in many body parts
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This note was uploaded on 01/27/2010 for the course BIO 37282 taught by Professor Padilla during the Fall '10 term at SUNY Stony Brook.

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14. Mollusca III Oct 19 - Phylum Mollusca snails, clams,...

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