The bivalves

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The bivalves

  1. 1. The BivalvesPhylum Mollusca
  2. 2. Anatomy• Two shells (valves) held together tightly by adductor muscles• No head, brain is a set of nerve cells (ganglia)• Gills to take oxygen from water• Mantle secretes the shell• Bilateral symmetry
  3. 3. Class Bivalvia – The Bivalves(clams, mussesls, scallops, oysters)
  4. 4. Habitat• Benthic – Most Sessile, few motile – Infauna – most burrow down – Epifauna – some live on seafloor • Mussels attach with byssal threads • Scallops swim by clapping shells together
  5. 5. -Most are planktivores-Incurrent & excurrentSiphons Feeding-Important filterfeeders-up to 25gallons of water/day
  6. 6. Bivalve Reproduction -Separate sexes -External fertilization and development
  7. 7. Pearl Formation• Mostly in oysters• Protection against parasites or grains of sand• Often not round• Natural pearls are more costly• Cultured pearls are made by inserting an object in the oyster
  8. 8. Clam Internal Anatomy

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