What is a bivalve?

A bivalve is a type of mollusk with a two-halved shell. Though they look different, all of the species we are concerned with fall into the bivalve category. In fact, there are well over 10,000 species of bivalves, occurring in a variety of extreme habitats. In addition to their shells, they are characterized by their “foot,” the muscle that protrudes from the shell. Sometimes they have an  extremely pronounced foot, like geoducks, to bury deep into substrate. However, some species are stationary and  barely have any foot at all, like oysters.

Bivalve anatomy. Notice that the foot muscle makes up about a third of the volume. In geoducks it is much more!