Mussels
Mussels comprise a family of shellfish that contains over 250 different species. They are found in the low to mid intertidal region of the shore and are often found in thick mats, called mussel beds. Examples of mussels include blue mussels, or Mytilus edulis, which are carefully cultivated for sustainability, and the California mussel, Mytilus californianus, which can reach over 7 inches in length.
Clams
There are in excess of 2,000 species of clam, and some species are commercially farmed for consumption. Edible clams usually come in two varieties, typified by shell hardness: soft-shelled clams, also known as Ipswich clams, have thinner, more brittle shells, while hard-shelled clams have thicker shells. Soft-shelled clams, scientific name Mya arenaria, are found in tidal mudflats and are one of the most typical types of clam used in cooking. Hard-shelled clams are more tolerant of saline conditions and are found to a greater depth than Ipswich clams. Examples of hard-shelled clams include quahog, which are used in chowder, cherry stone, which are eaten raw or steamed, and geoduck, which are used in sashimi or stir-fried.
Scallops
Scallops are a shellfish whose taste more closely resembles that of fish. The primary part of the scallop consumed is the abductor muscle, which opens and closes its shell. Examples of scallops include sea scallops, a large species of scallop and the one most commonly found off the North American coast; spiny scallops, which are found off the Washington Coast and are a little larger than sea scallops; calico scallops, which are a small species found in the Gulf of Mexico; and Bay scallops, which are the smallest North American species and rarer than the other three, thus commanding a higher price.
Oysters
Oysters are thought to have originated during the Triassic Period, approximately 200 million years ago, according to thenibble.com. While there are many species of oysters, only three are primarily farmed in U.S. waters and consumed in large quantities. The Kumamoto oyster is originally from Japan and is farmed in the Bay area. The Pacific or Japanese oyster also originates in Japan and has become the most widely cultivated oyster species in the world. Finally, the Virginia oyster is found from Nova Scotia all the way south to South America, and their meat is both briny and sweet.