BIOL 321 Lecture Notes - Lecture 18: Bivalvia, Anatomical Terms Of Location, Mollusca
18 Nov 2016
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Document Summary
The bivalve body is adapted to burrowing into soft substrates whereas chitons are adapted to cling to rocky substrates. Hinge and adductor muscles- proteinaceous hinge that holds the two shell valves together. Reduction in number of dorso-ventral muscles (compared to a chiton). Two adductor muscles (posterior and anterior) and a hinge ligament. Contraction of adductor muscles pulls the two shell valves together. The opening of the shell is entirely due to the hinge ligament. Shell secretion- shell is in the form of two shell valves that are hinged dorsally. There are sensory structures around the edge of the mantle margin. Have two siphons (excurrent and incurrent), and a foot that projects out (is laterally flattened) Have spacious lateral mantle cavities to host the ctenidia. Feeding- groups are based on what their ctenidium look like: protobranch- deposit feeding using palp tentacles. They are buried in the substrate and have a long pair of siphons extending to the surface of the sand.
