The genus Mercenaria includes the quahogs, consisting of Mercenaria mercenaria, the northern quahog or hard clam, and M. campechiensis, the southern quahog. These two species commonly hybridise where their ranges overlap.
Mercenaria mercenaria is further subdivided in the marketplace and thence in the kitchen by size: the largest being the quahog or chowder clam, then smaller cherrystones, and smallest littlenecks; some markets also differentiate top necks which are intermediate in size between cherrystones and littlenecks. The smaller clams are eaten raw throughout New England, New York, and New Jersey; the larger clams are more suited for cooking.
Other species within the genus include the venus clamM. stimpsoni found in north Pacific waters. All these species were formerly placed in the related genus Venus.
Several other species are known only from fossils. These mollusk lived from Oligocene to Quaternary (from 23.03 to 0.0 Ma). Fossil shells have been found in the sediments of Russia, Japan, Indonesia, United States and Brazil.
Fossil shell of Mercenaria permagna, Pleistocene of United States
A large quahog pearl and diamond ring, in platinum.A collection of quahog pearls, ranging in color from white to purple.
The northern quahog clam is known for producing very rare and collectible, non-nacreous pearls known for their purple color. Quahog pearls are often button-shaped, and can range in color from white to lavender, to purple.[4]
