A clam is a generic term for many kinds of bivalve molluscs, some of which are edible.

Clams, like most molluscs, also have open circulatory systems, which means that their organs are surrounded by watery blood that contains nutrients and oxygen. They feed on plankton by filter feeding. Clams filter feed by drawing in water containing food using an incurrent siphon. The food is then filtered out of the water by the gills and swept toward the mouth on a layer of mucus. The water is then expelled from the animal by an ex-current siphon.