Clam

For other uses, see Clam (disambiguation).

Littleneck clams; the pictured molluscs are of the species Mercenaria mercenaria.

Maxima clam (Tridacna maxima).

File:Shelllarcomuseum.jpg

Moche Clam. 200 C.E. Larco Museum Collection Lima, Peru.

A clam is a kind of mollusc that has a shell divided into two pieces called valves, in other words, a clam is a bivalve mollusc.

The word "clam" has no real taxonomic significance in biology. However in the USA the word can sometimes be used to mean any bivalve mollusc. It can also be used to mean a bivalve other than an oyster, mussel, or scallop, and that has a more-or-less oval shape, or a freshwater mussel (Merriam-Webster Dictionary.). The word clam is also often used to mean any one of many edible bivalve species which live buried in sand, hence, "digging for clams" or clam digging.

Not all edible clams are round or oval in shape: the razor clam has an elongated shell whose shape suggests a straight razor.

In October 2007 an Arctica islandica clam 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.

Anatomy

A clam's shell or two valves are connected by a hinge joint and a ligament that can be external or internal. Two adductor muscles 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.

Clams, like most molluscs, also have open circulatory systems, which means that their organs are surrounded by watery blood that contains nutrients and oxygen. Clams eat plankton, and they themselves are eaten by small sharks and squid.

In culinary use, the term "clam" most often refers to the hard clam Mercenaria mercenaria but it may refer to several other species such as the soft-shell clam Mya arenaria. Clams can be eaten raw, steamed, boiled, baked or fried; the method of preparation depends partly on size and species. Clam chowder is a popular soup in the U.S. and Canada. In Italy, clams are often an ingredient of mixed seafood dishes, or are eaten together with pasta.

The Maxima clam Tridacna maxima, a species of giant clam, is popular with saltwater aquarium hobbyists.

The Moche people of ancient Peru worshipped the sea and its animals. They often depicted clams in their art.

Examples of clams

• The ark clams, family Arcidae
• The nut clams, family Nuculidae
• The pointed nut clams, family Nuculanidae
• The duck clams or trough shells, family Mactridae
• The marsh clams, family Corbiculidaess
• The file clams, family Limidae
• The hard clam or Northern Quahog: Mercenaria mercenaria
• The Soft clam: Mya arenaria
• The surf clam: Spisula solidissima
• The ocean quahog: Arctica islandica
• The Pacific razor clam: Siliqua patula
• The giant clam: Tridacna gigas
• Chink or Asiatic clam: genus Corbicula
• Peppery furrow shell: Scrobicularia plana
• Pismo clam: Tivela stultorum (8 inch shell on display in the Pismo Beach Chamber of Commerce)
• Geoduck clam: Panopea abrupta or Panope generosa (largest burrowing clam in the world)
• The Atlantic jackknife clam: Ensis directus

See also

Wikimedia Commons has media related to:

Bivalvia

• Clam bake
• Clam boil

References

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