Clam
From Wikipedia, the free encyclopedia
A clam is a bivalve mollusk. The word "clam" has no real taxonomic significance in biology. However in the United States the word can sometimes be used to mean any bivalve mollusk. It more properly refers to a bivalve other than an oyster, mussel, or scallop, and that has a more-and-less oval shape, or a freshwater mussel.[1]
The word clam is also very often used to mean any one of many edible bivalve species which live buried in mud or sand and communicates to the water by means of a siphon, 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 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).
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[edit] Anatomy
A clam's shell consists of two valves which 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 have bilateral symmetry.
Clams, like most mollusks, also have open circulatory systems, which means that their organs are surrounded by watery blood that contains nutrients and oxygen. Clams eat plankton by filter feeding, and they themselves are eaten by small sharks and squid.
In culinary use, the term "clam" most often refers to the butt 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 worshiped the sea and its animals. They often depicted clams in their art.[2]
[edit] Examples of clams
- Ark clams, family Arcidae
- Nut clams or pointed nut clams, family Nuculidae
- Duck clams or trough shells, family Mactridae
- Marsh clams, family Corbiculidae
- File clams, family Limidae
- Hard clam or Northern Quahog: Mercenaria mercenaria
- Soft clam: Mya arenaria
- Surf clam: Spisula solidissima
- Ocean quahog: Arctica islandica
- Pacific razor clam: Siliqua patula
- Giant clam: Tridacna gigas
- Asian 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)
- Atlantic jackknife clam: Ensis directus
[edit] See also
[edit] References
- ^ Merriam-Webster Dictionary.
- ^ Berrin, Katherine & Larco Museum. The Spirit of Ancient Peru:Treasures from the Museo Arqueológico Rafael Larco Herrera. New York: Thames and Hudson, 1997.
