Most bivalves are filter feeders, using their gills to capture plankton and tiny particles of food from the water. Some are scavengers, some parasites and a few are predators, sucking in small crustaceans and worms. In burrowing species, there may be long siphons stretching from the body to the surface, one for drawing in and the other for pushing out water.
Predators of bivalves include sea stars, eels, gastropds (e.g. whelks), octopuses, oystercatchers (birds) and humans.
Bivalves use their muscular foot to attach itself to a surface or to burrow. Scallops using jet propulsion. The rapid closing of the valves squirts water out of the mantle cavity, and the animal moves in the opposite direction.
Unlike other molluscs, bivalves do not have a brain and have poorly developed senses with only Scallops having complex eyes. The mantle forms a thin sheet (membrane) which surrounds the body and secretes the valves, ligament (opens the shell) and teeth. The major component of the shell, like other Molluscs, is calcium carbonate.
Bivalves are usually male or female but some are hermaphrodites. Fertilisation is external and there are a number of larval stages before they bvecome adults.
Many bivalves (e.g clams and oysters) are important food sources all over the world.