BIVALVIA
General information:
- The class bivalvia has the 2nd biggest molluscan class with about 30,000 species
- bivalves includes the clams, oysters, mussels, and scallopes
- they have a sheet-like mantle and a shell consisting of 2 valves which cover these laterally compressed animals
- many bivalves are edible and some of them have pears
- since bivalves are filter feeders, they are valuable in removing bacteria from polluted water
Shell and Associated Structures:
- the two convex halves of the shell are called valves
- the oldest part of the shell id called the Umbo, a swollen area near the shell's anterior margin
- the shells form as a single structure embryonically
- the mantle in the region of the hinge , secretes relatively greater quantities of protein and relatively little calcium carbonate. the result is an elastic hinge ligament
- adductor muscles at either end of the dorsal half of the shell close the shell
- the bivalve mantle attaches to the shell around the adductor muscles and near the shell marigin
gas exchange, filter feeding, and digestion