Bivalve mollusks (e.g., clams, oysters, mussels, scallops) have an external covering that is a two-part hinged shell that contains a soft-bodied invertebrate. … An internal organ called the mantle secretes calcium carbonate so that as the inner invertebrate grows, the outer shell provides a roomier home.

How do you identify a bivalve?

The bivalve shell is composed of two valves (“bi-valves”). The valves are joined by a hinge composed of tiny “teeth” and usually also an elastic ligament. The number, size and shape of the teeth as well as the position of the ligament are important characters for the identification of bivalves.

What is the main characteristic of bivalve molluscs?

Discover the characteristics of bivalves Clams, cockles, mussels, oysters, scallops, and shipworms are bivalves. Most are completely enclosed by the shell, the two valves of which are joined by an elastic ligament, and by two sheets of tissue called the mantle. Bivalves have no head.