Arctica islandica, commonly known as the ocean quahog, is an edible marine bivalve mollusk native to the North Atlantic ocean. It is commonly exploited commercially. This species is also known by a number of different common names, including Icelandic cyprine, mahogany clam, mahogany quahog, black quahog, and black clam.
The clam superficially resembles the quahog or hard clam, but the shell in this species is rounder, the periostracum is usually black, and on the interior of the shell, the pallial line has no indentation, or sinus. Unlike the quahog, which lives intertidally and can be collected by clam digging, this species lives subtidally, and can only be collected by dredging.
In 2006 and 2007, separate specimens collected off the coast of Iceland were found to be more than 400 years old, making the Arctica islandica clam the longest lived animal species ever recorded.
These "arctic clams" are prized for sushi
(arranged food). Blanched and halved along the flat side they are common for topping Nigiri sushi. The shape of the flesh of the foot of the clam somewhat resembles the claw of a crab. It is coloured creamy yellow at its base graduating to a deep red at the tip. This is most likely the reason for its moniker "mothers tongue".
In October 2007, researchers from Bangor University
in North Wales
determined that an ocean quahog clam dredged off the Icelandic coast was between 405 and 410 years old by drilling through and counting rings on its shell (a technique known as sclerochronology
). This made it the longest-lived
animal on record.
The clam was nicknamed "Ming" after the Chinese dynasty that ruled when the clam settled (the mollusc equivalent of being born). The researchers are uncertain how long the clam, which died during the assessment process, might have lived had it been left on the ocean floor.
Help the Aged, a UK based charity, has contributed £40,000 towards studying quahog longevity.