Clam, common name for any bivalve (hinged shell) mollusc, referring especially to those of economic significance burrowing in beaches or the seafloor. In Canada numerous species are fished for human consumption. On the West Coast butter and littleneck clams (Saxidomus giganteus, Protothaca staminea respectively) are most important, but the accidentally introduced Manila clam (Tapes philippinarum) is also taken. Recently, an important fishery for the geoduck (Panope abrupta, formerly P. generosa) has developed. It is the largest clam of the North Pacific, with a body weight up to 5 kg and a lifespan of up to 150 years. On the East Coast, the soft-shell clam (Mya arenaria) and the ocean quahog (Arctica islandica) are commercially important.