|Edible clams in the family Veneridae|
Clam is a word which can be used for all, some, or only a few species of bivalve mollusks; the word is a common name which has no real taxonomic significance in biology. It is however quite widely used as part of the common names of bivalves, and also has significance in fisheries and cuisine.
The word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.
In October 2007 an Arctica islandica clam, caught off the coast of Iceland, was discovered to be at least 405 years old, and was declared the world's oldest living animal by researchers from Bangor University, see Ming (clam).
In regard to the concept of edible clams, most species of bivalves are at least potentially edible, but some are too small to be useful, and not all species are considered palatable.
A clam's shell consists of two (usually equal) valves, which are connected by a hinge joint and a ligament which can be external or internal.
In most clams, two adductor muscles contract to close the shells. The clam has no head, and usually has no eyes, (scallops are a notable exception), but a clam does have kidneys, a heart, a mouth, and an anus. For more information see bivalve and pseudofeces.
A clam does not have any of the five senses so they cannot smell, taste, feel, hear or see. The shell has 3 layers. The top one is called mother-of-pearl because it is a coating of pearl material.
Clams have a burrowing foot that they use to dig down into the sand or mud to hide. If you go to the beach and see little holes that appear in the sand each times the waves go away, it is probable that clams made them. Scientists classify clams by how far down they dig and what kind of surface they dig into. Some burrow less than an inch under the sand, while others dig several inches below the surface.
As food items
Clams can be eaten raw, steamed, boiled, baked or fried; the method of preparation depends partly on the size and species. They can also be made into clam chowder (a popular soup in the U.S. and Canada) or they can be cooked using hot rocks and seaweed in a New England clam bake.
In an aquarium
The Maxima clam Tridacna maxima, a species of giant clam, is a popular species with saltwater aquarium hobbyists. A living freshwater clam can work like a filter in fish tanks to keep the water clean.
Images for kids
A clam shell (species Spisula solidissima) at Sandy Hook, New Jersey
Clam Facts for Kids. Kiddle Encyclopedia.