The hard shell clam is also known as the quahog (also spelled quahaug) in New England and the Northeast. Based on the size of the shell, they are also called Little Necks and Cherrystones.
The quahog's scientific name is Mercenaria mercenaria. Like most commercial shellfish, the quahog is a bivalve mollusk. Mollusks comprise a group of soft-bodied animals that includes snails, clams, and sea slugs. Their most common characteristic is that of a soft body contained by a shell. They are classified as bivalve because they have hinged shells, or "valves."
Bivalves obtain their food by filter feeding. Water is taken in through a siphon and passed over the gills, which are specially adapted to filter out food (microscopic algae and other small organic particles). The filtered water is then expelled via another siphon. A large clam can filter about a gallon of water in one hour.
Quahogs are plentiful between Cape Cod and New Jersey, but their range is along the entire Atlantic seashore. Quahogs prefer low salinity and thus are largely found near bays and estuaries where the mixing of fresh and salt water provides ideal conditions.
In general, quahogs grow to legal size in 3 or 4 years. Like a cross-section of a tree, a quahog's age can be determined by counting the growth rings on its shell. As quahogs get older, they grow more slowly, making the rings difficult to determine. Researchers estimate that the largest quahogs are as much as 40 years old. According to NOAA, the species may live to be 200 years old.
Hard shell clams bury themselves and live in soft, sandy sediments. The principal gear used in the commercial fishery to harvest the clam is the hydraulic dredge, am apparatus that uses jets of water to reveal ocean quahogs from the sand. Most hard shell clams grow to be 3 to 5 inches wide.