Guide to Clams: How to Identify and Cook 8 Types of Clams

Clams are bivalve mollusks belonging to the Bivalvia class—a group of sea- and freshwater invertebrate animals that have a two-part hinged shell, including mussels, oysters, and scallops. Clams have two adductor muscles that hold their shells together and a burrowing foot that allows them to dig. They live most of their lives buried under sand or mud in oceans or rivers.

There are about 150 edible types of clams, but only a handful of them are commonly available commercially.

1. Hard Clams

Hard clams, also known as quahogs (a word that comes from the Narragansett word poquauhock), include two main varieties:

• Northern quahogs (Mercenaria mercenaria), also known as Atlantic hard-shell clams, live in intertidal zones on the Atlantic coast from the Gulf of St. Lawrence to the Gulf of Mexico. They have a grayish-white shell and are sold by different names depending on their size. Littleneck clams are the smallest northern quahog you can buy. They are named after Little Neck Bay on Long Island and are typically one and a half inches wide. Littlenecks are small, tender, and sweet. You can eat them raw on the half shell or steamed in pasta. Cherrystones are about two and a half inches wide. You can eat them grilled, raw, or stuffed and broiled. Chowder clams are the largest northern quahog—three inches and wider. Since they’re tough, they’re generally not eaten raw; instead, they’re cooked and chopped for chowders.
• Southern quahogs (M. campechiensis) can be up to six inches long and live in intertidal zones from the Chesapeake Bay to the West Indies. They have a heavy white shell and can be eaten in the same manner as northern quahogs.

2. Mahogany Clams

Mahogany clams (Arctica islandica) are also known as ocean quahogs, and they live in the North Atlantic, especially around Maine. They are hard-shell clams that are distinct from northern and southern quahogs; they have round, dark brown or black shells and live deeper in the ocean than hard clams. They have a slower life cycle than other clams: They take about six years to reach maturity and can live to be hundreds of years old. Mahogany clams have a stronger flavor than hard clams and are particularly suited to pasta dishes.

3. Geoducks

Geoducks, pronounced “gooey-ducks,” are popular in Asia and the Pacific Northwest. Their meat is chewy and crunchy with a briny flavor. There are two common species of geoduck.

• Pacific geoducks (Panopea generosa) live on the Pacific coast from southern Alaska to Baja California. With shells seven to nine inches long and outer siphons up to four feet long, they are the largest burrowing clam. (A single Pacific geoduck can weigh up to eight pounds.) They have a white oblong shell. The siphon is often served raw as sushi or ceviche, while the belly has a stronger flavor and is typically used in soups or stir-fried.
• Atlantic geoducks (P. bitruncata) live on the Atlantic coast from North Carolina to the Gulf of Mexico and are effectively indistinguishable from their Pacific relatives.

4. Soft-Shell Clams

Also known as steamers or longneck clams, soft-shell clams (Mya arenaria) are iconic in New England but live on both sides of the North Atlantic and on the Pacific coast. They are also known as Ipswich clams because Ipswich, Massachusetts, is a major processing center for soft-shell clams. Soft-shell clams have long siphons and grayish-white, oval-shaped shells that are usually one and a half to three inches long—but can grow up to six inches long. Their thin, brittle shells gape open, which can make them sandy, so you need to purge them before cooking. Serve smaller soft-shell clams either deep-fried or steamed and accompanied by the steaming liquid (to swish the clams to remove excess grit) and butter. Use larger clams for chowder.

5. Razor Clams

Clams in the Solenidae family, of the genera Ensis and Solen, are razor clams. Their shells are brittle and gape open. There are two common types of razor clams.

• Pacific razor clams (Siliqua patula) aka northern razor clam, are oval in shape and have a long, protruding siphon. They are common in the Pacific Northwest. Tender and sweet, they can be eaten raw or cooked.
• Atlantic razor clams (Ensis leei or Ensis directus), also known as Atlantic jackknife clams, are thinner and milder, and sweeter in flavor (and less common) than Pacific razor clams. Their shells are up to eight inches long and resemble a straight razor. Their shell is delicate and they can be difficult to clean. Atlantic razor clams can be steamed or grilled.

6. Manila Clams

Manila clams (Venerupis philippinarum or Ruditapes philippinarum) are a type of small, sweet hard-shell clam found in the Pacific ocean. On the West Coast of the United States, they’re known as steamer clams. They’re best eaten raw, steamed, or in pasta. They have a less briny flavor than other types of clams.

7. Surf Clams

Surf clams (Spisula solida) are large (up to six inches long) and are perfect for clam chowder. They account for almost one-third of the clam harvest in the United States, where they are mainly found in deep water off the coast of New Jersey.

8. Washington Clams

A Pacific coast clam of the genus Saxidomus, Washington clams are also known as butter clams for their melty mouthfeel. They are commonly steamed or grilled. There are two types:

• Northern Washington clams (S. giganteus) can be found from Alaska to San Francisco and are up to four inches in diameter.
• Southern Washington clams (S. nuttalli) are larger (up to seven inches) and have purple markings inside their shells. Confusingly, these clams are not found in Washington at all: They are harvested from Humboldt Bay in Northern California to Baja California in Mexico.

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