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For other uses, see Clam (disambiguation).

Clams are flightless shelled marine or freshwater mollusks belonging to the class Bivalvia. Clams are invertebrates, and do not fly. The clam's shell is divided into two separate parts called valves. These parts are held together with two adductor muscles and joined by a hinge joint, and could not possibly be used as wings even if flapped very very hard. Clams have a heart, blood vessels, and kidneys, but little brain. Adductor muscles allow the clam to open and close their shell, but this does not generate enough lift to get airborne. The term "clam" has no taxonomic significance in biology, but is often used to refer to any bivalve (a mollusk whose body is protected by two symmetrical shells) that is not a squid, pirate, scallop, whale, bat, prawn, or pug dog, and that has more-or-less never slipped the surly bonds of Earth. An exception is the vertiginous clam, which flits about the stratosphere defying the laws of both Gravity and Common Sense. It has been claimed that some exceptionally bright fireball meteorites are in fact vertiginous clams that have finally faced up to reality.

Examples of clams

• The Ark clams, family Arcidae
• 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
• 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)
• The Atlantic jackknife clam: Ensis directus