Clams, mussels, oysters, and scallops are bivalve mollusks. This means they have shells that consist of two parts; or valves, which are hinged dorsally and free ventrally. The valves completely enclose the organisms' body. All shellfish are filter feeders which mean they extract food from the surrounding water in the form of tiny particles called plankton. They reproduce by discharging microscopic eggs and sperm into the surrounding water. Each mature female spawns millions of eggs per season.
Learn about the most common shellfish that can be found in New York's waters below:
Hard Clam
(Mercenaria mercenaria)
Hard clams are also known as "Chowder Clams", "Northern Quahogs" and "Round Clams". These clams have hard, thick shells that can grow to about four inches in length. The shell's color is pale brown with a distinctive purple stain on the interior. They have a muscular foot which they use to burrow deep into the sediment.
Hard clams are a commercially important species that are harvested both by commercial fishermen (baymen) and recreational clammers. They have an average lifespan of four to eight years, however specimens as old as 40 years of age have been found. Hard clams are also given common names based on their size:
- Littlenecks: Smallest hard clams able to harvest, 1" thickness (vertically). Often served raw on the half-shell.
- Middlenecks/Topnecks: Average 2" across the shell (horizontally). Can be served raw, steamed, or grilled.
- Cherrystones: Approximately 2.5" across. Versatile use for raw, cooked, and baked.
- Chowders: Larger than 3" across. Best used chopped and cooked in soups or as fried clams.
Habitat: East coast of the United States, ranging from the Gulf of St. Lawrence to the Gulf of Mexico. They are found in the sand and mud habitats of the intertidal and sheltered subtidal zones. The intertidal zone is the area of marine shoreline that is exposed to air at low tide and covered with seawater at high tide. The subtidal zone is the area of marine shoreline that is below the intertidal zone and is submerged most of the time, portions of this zone may be exposed briefly during extreme low tides around full and new moons. Hard clams can tolerate salinities ranging from 15 ppt to 35 ppt.
Soft Shell Clam
(Mya arenaria)
Soft-shelled clams are also known as "Long Necks" and "Steamers". They are thin, oval-shaped bivalves that can grow up to four inches long. The shells are chalky white with a thin, parchment-like covering that varies in color from brownish to yellowish or gray. They have two long siphons that are covered in a thick, black skin. The siphons are used to take in fresh seawater so they can breathe while the tide comes in, and because of this, the siphons may be the only part of the clam a beachgoer will see. Soft-shell clams also have a large muscular foot which they use to burrow into the sediment.
Habitat: East and West coast of the United States, ranging along the Atlantic coast of North America from Northern Canada to Cape Hatteras, North Carolina. They are also in the Pacific Coast regions of Alaska, California, Washington and found in Western Europe. They are found in the intertidal zone buried under sand or muddy sand along beaches and in bays. They can tolerate salinities ranging from 5 ppt to 30 ppt.
Ocean Quahog
(Arctica islandica)
Ocean quahogs are also known as "Black Clams" and "Mahogany Quahogs". They are thick and oval-shaped bivalves that can grow up to 4.3 inches long. The shells are a dull gray and have growth rings that can be used to determine their age. The interiors are white with a purple border. Quahogs bury themselves in the ocean floor and pump in oxygen-filled water and food particles through siphons which are extended above the surface of the ocean floor. Quahogs are very slow growing and extremely long-lived. Individual clams have been reported to be hundreds of years old.
Habitat: Western Atlantic as far south as Cape Hatteras, North Carolina. They burrow in a variety of sediments from sand to muddy sand that ranges from fine to coarse at water depths between 25 and 1,500 feet. They prefer salinities ranging from 31 ppt to 32.8 ppt.
Atlantic Bay Scallop
(Argopecten irradians)
Atlantic bay scallops are also known simply as "Bay Scallops". Their shells are ribbed and have a distinctive wing-like hinge. They can grow to approximately three inches in length. The shells vary in color and can be blue-black, orange, reddish-brown, or white. Within the shells is a single adductor muscle that closes the two shells tightly together. This muscle allows the scallop to clap its shells quickly and strongly which propels the animal through the water. It's the adductor muscle that is the only part of the scallop commonly eaten. Unlike most bivalves, the bay scallop does not have a muscular foot for digging or a siphon for water intake.
Along the edge of a bay scallop shell are 30 to 40 bright blue eyes. Each eye has a cornea, a lens, an optic nerve, and a retina which enables it to see movements and shadows. This allows them to detect predators. In addition to eyes they also have tentacles along the edge of their shells. The tentacles contain cells that are sensitive to chemicals in the water. These cells help the animal react to its environment. Bay scallops grow quickly, and rarely live past three years of age.
Habitat: East Coast from Cape Cod to the Gulf of Mexico. On Long Island, Bay Scallops are mostly found in the small bays and harbors, most notably in the Peconic Bay Estuary which lies on the eastern end of Long Island. Bay scallops have also been found in Great South Bay, Moriches Bay, and Shinnecock Bay. Their preferred habitats are within eelgrass beds on sandy and sandy-mud bottoms. Juvenile bay scallops use byssal threads to attach themselves to aquatic plants and rocks to keep them away from predators. They prefer salinities ranging from 31 ppt to 32.8 ppt.
Atlantic Sea Scallop
(Placopecten magellanicus)
Atlantic sea scallops are also known as "Giant Scallops". Their shells are smooth and lack the prominent ribbing that is characteristic of most other scallop shells. It is thought that the sea scallop's smooth shell is an adaptation to allow it to propel itself farther and faster. They can have very large shells- up to nine inches in length. The upper shell is usually brown or reddish-pink in color, and the lower shell is cream-colored or white. Like bay scallops, sea scallops shells are held together by an adductor muscle and their mantles contain hundreds of bright blue eyes. They do not have a muscular foot for digging or a siphon for water intake.
Atlantic Sea Scallops are the largest wild scallop fishery off northeastern United States and eastern Canada. Most of the rest of the world's production of scallops are from Japan (wild, enhanced, and aquaculture), and China (mostly cultured Atlantic Bay Scallops). They can live up to 20 years.
Habitat: Northwest Atlantic Ocean; from Newfoundland to Cape Hatteras, North Carolina, though they are found in saltwater environments worldwide. Their habitat ranges from the intertidal zone to the deep sea. Most prefer beds of seagrass amid shallow sandy bottoms, although some attach themselves to rocks or other substrates. They inhabit waters with salinities characteristic of oceanic waters.
Eastern Oyster
(Crassostrea virginica)
Eastern oysters are also known as "American Oysters", "Atlantic Oysters", and "American Cupped Oysters". They have thick, deeply cupped elongated shells that are bumpy and rough. They are a pale gray to white in color and can grow up to eight inches long. Oysters are reef building organisms which means they attach themselves to rocks, shells or other oysters and over time, the accumulation forms a reef. Juvenile oysters, called spat, also attach to these substrates.
Like many other oysters, the eastern oyster makes pearls. Pearls are formed when a sand grain or other irritating particle gets stuck inside the oyster's shell. To get rid of this irritant the oyster covers the sand grain with a smooth substance called nacre; a form of calcium carbonate that is similar to the material of its own shell. After receiving several layers of nacre, the sand grain eventually becomes a pearl. Eastern oysters can live up to approximately 20 years.
Habitat: East Coast of the United States from Canada to the Gulf of Mexico. They are surface-dwelling mollusks that thrive on reeds and inhabit intertidal and subtidal areas in water depths between eight and twenty-five feet. They can tolerate salinities ranging from 5 ppt to 30 ppt.
Atlantic Surfclam
(Spisula solidissima)
The Atlantic surfclam is also known as the "Beach Clam" or "Skimmer Clam". Surfclams have a relatively strong shell that is somewhat triangular in shape. Shells are smooth and are white or yellowish in color. They can grow up to nine inches long. Offshore populations are typically larger and older than those found inshore. Surfclams are the most common shells found on ocean beaches south of Cape Cod. They may live to about 30 years of age.
Habitat: East coast from Nova Scotia to Cape Hatteras, North Carolina. Surfclams are found in sand and muddy seabeds from subtidal areas to waters roughly 100 feet in depth. Adults prefer salinities above 14 ppt and 16ppts for larvae.
Blue Mussel
(Mytilus edulis)
The blue mussel is also known as the "Edible Mussel". They are shaped like rounded triangles and are blue black to brown in color with a shiny violet interior. Shells have a slender brownish foot, which houses the byssus gland that produces a strong, thread-like fiber called the byssal threads that allows the mussels to attach themselves to substrates. The threads harden upon contact with the water and are quite tough, however they are not permanent. They use byssal threads to attach to docks, pilings, rocks, and most any solid object. They live in close proximity to other Blue Mussels and together they form dense beds that host a rich community of benthic invertebrates including crustaceans and marine worms. Beds often break up during major storms.
Blue mussels can grow up to four inches long, and possess two short siphons inside their shell and direct the flow of water. They are known to have significant water filtering capacity and readily absorb water-borne toxins. Many organizations use them as indications of harmful algal blooms (HABs). DEC conducts a Marine Biotoxin Monitoring Program from spring through fall to identify waters where any HABs may be occurring. This is done to protect human health because toxins accumulate in the tissues of animals that unknowingly filter the harmful toxins. If you were to eat a shellfish that has consumed harmful biotoxins, it poses a serious threat to both your gastrointestinal and neurologic health.
Habitat: Coastal areas of the northern Atlantic Ocean, including North America, Europe, and the northern Palearctic. Found in intertidal shallow water along the shoreline attached to a number of solid objects. They prefer cool water, hard substrates such as gravel and shell beds, rocks, and submerged human-made structures with good water flow, but they are also able to withstand great extremes, including drought, excessive heat, and freezing temperatures. If blue mussels are left exposed to air when the tide goes out, they survive by passing air over their damp gills to breathe. They prefer areas of high salinity.
Bank (Ribbed) Mussel
(Geukensia demissa)
Ribbed musses are oval in shape with dark glossy, ribbed shells ranging from olive or yellowish-brown to black in color. The interior is silvery white with purplish tints. They can grow up to four inches in length. Like most bivalves, this species has a muscular foot which allows the animal to slowly move through sediment. The foot can also secrete byssal threads.
Although ribbed mussels are edible, they are not as commonly eaten as blue mussels. The meat is rubbery, tough to chew, and can also possess organic bacteria which gives it a slightly metallic taste. It is important to harvest ribbed mussels at high tide, not low. At low tide, the mussels tightly close their shells which traps in waste products that can be toxic to humans.
Habitat: Atlantic coast of North America, from the southern Gulf of St. Lawrence, Canada to northeastern Florida and along the Gulf of Mexico from Florida to Yucatan. They live partially embedded in marsh sediment in aggregations of individuals attached together by byssal threads. These clumps of Atlantic Ribbed Mussels help contain erosion in wetlands because they exist tightly packed together among plant roots. This helps trap wetland sediments which build a secure marshy coastline.
The mussels are most abundant at the lower elevations within the marsh, especially at the marsh edge and along creek banks. They can survive in extreme water temperatures from freezing to excessive heat and can tolerate salinities from 5 to 70 ppt.