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Clam Species Guide

Littlenecks, topnecks, steamers, mahoganies…the shellfish industry is filled with confusing terms for clams, some of which refer to the variety of clam, and some merely refer to the size of the clam. Here’s a quick and easy guide to help you sort them out.

Atlantic Clams


Mercenaria mercenaria

Synonyms: Atlantic Hard Shell Clams, Round Clam, Quahaug, various size names (see below)

Origin: Wild

Size: See Chart (below)

Ocean: Atlantic

The quintessential American hard-shell clam, quahogs are the clam most people think of when they think of clam chowder, clam strips, baked clams, spaghetti with clam sauce, etc. When in doubt, choose quahogs.

Quahogs are graded by size, with the different grades having different traditional names:

Littlenecks10-12 per pound
Middlenecks8-10 per pound
Topnecks5-7 per pound
CherrystonesAvg. 3 per pound
Chowders1-2 per pound

How They’re Prepared:

Small Quahog Clams (Littlenecks, Middlenecks & Topnecks)

A great choice for any dish where you want to serve whole clams. Pasta dishes, soups, stews, appetizers, simply steamed…whatever you’d like. Some people even like to enjoy littleneck clams raw.

Large Quahog Clams (Chowders & Cherrystones)

Usually chopped or ground before use. They’re an ideal choice for soups (usually chowders), fried clam strips and baked clams (aka “stuffies”).


Arctica islandica

Synonyms: Ocean Quahogs, Black Quahog, Black Clam, Mahogany Quahog

Origin: Wild

Size: Varies – Typically Commercially Available at 7-8 per lb

Ocean: Atlantic

Mahogany clams are a variety of dark colored Atlantic hard-shelled clam with a stronger, brinier flavor than the common quahog.

How They’re Prepared:

Mahogany clams cook similarly to the smaller quahogs. Their more pronounced flavor allows them to stand out in dishes with strong ingredients like bell peppers and tomatoes. Consider using them in Manhattan-style clam chowder, cioppino, and similar dishes.


Ensis directus

Synonyms: Razor Shells, Jackknife Clams, Bamboo Clams

Origin: Wild

Size: Up to 10” Long

Ocean: Atlantic

One of the rarer clam varieties, razor clams get their name from their long, thin shape that resembles a straight razor. In the US you can find both Atlantic and Pacific varieties of razor clam (there are also additional types in Europe). Atlantic razor clams are straighter, thinner, and more highly prized than Pacific razor clams. They dig quickly when threatened and can be very hard to catch – thus expensive and hard to find commercially.

How They’re Prepared:

Atlantic razor clam meat can be prepared similarly to other clams – steamed, fried, sauteed, etc. Because their shape is so distinctive, Atlantic razors are often served in the shell (whether they’ve been cooked in it or not).


Mya arenaria

Synonyms: Softshell Clams, Ipswich Clams, Longnecks, Sand Gapers, Belly Clams, Fryer Clams

Origin: Wild

Size: 12-15 clams per lb

Ocean: Atlantic

Steamer clams are an East Coast variety with softer shells and small, chewy necks. They never completely close, leaving room for the neck to protrude from the shell. Their flavor is sweeter and creamier than most other clam varieties.

How They’re Prepared:

Steamer clams are most often steamed or shucked, breaded and fried. Before cooking them the dark outer membrane around their “necks” should be removed.

Pacific Clams


Venerupis philippinarum

Synonyms: Asari, Japanese Cockle, Japanese Carpet Shell, Japanese Littleneck, Filipino Venus

Origin: Farmed

Size: Small Grade = 25-35 per lb

Ocean: Pacific

Originally Japanese in origin, manila clams were accidently introduced to the American west coast during the seeding of Japanese oyster varieties. They are a hard-shell variety with ridges and are prized for their cleaner, sweeter flavor.

How They’re Prepared:

Manila clams can be cooked similarly to smaller Atlantic Quahog Clams (littlenecks, middlenecks & topnecks) – steamed, shucked & fried or sauteed, etc. They can also be eaten raw.


Panopea generosa

Synonyms: Mirugai, Mud Duck, Elephant-Trunk Clam, King Clam

Origin: Farmed

Size: 1 ½ - 2lbs each

Ocean: Pacific

Extremely large, geoduck clams are unique to the coast of the American Pacific Northwest and Western Canada. They are considered a delicacy in Japan and some other parts of Asia. Because their shells don’t close completely or encompass the entire clam, geoducks are considered a soft shell clam.

Like Atlantic steamer clams, geoduck clams have two types of meat: siphon & body. Their siphon meat has a very mild flavor and a unique, crisp texture. Their body meat is crescent-shaped and wraps around their internal organs within the shell. It has a softer texture and a creamy, sweet, briny clam flavor.

Some cultures consider geoducks an aphrodisiac, likely because of their phallic appearance.

How They’re Prepared:

Geoduck siphon meat is often used in uncooked applications like sushi, sashimi, and ceviche. The stronger flavored body meat (aka belly meat) is typically cooked in soups, stir fry, steamed dishes, etc. The internal organs surrounded by the belly meat are edible, but are usually discarded.


Siliqua patula

Origin: Wild

Size: From 3” to 11” Long

Ocean: Pacific

When compared to Atlantic Razor Clams, the larger Pacific razor clam looks more like a stretched/elongated regular clam. They have tougher neck portions and more tender belly portions, somewhat akin to Atlantic Steamer Clams.

Pacific razor clam meat tends to be on the tough side compared to other varieties, but they are still quite tasty.

How They’re Prepared:

Pacific razor clams are often chopped or cooked for long periods in to make them tender. They can be broiled, baked, fried, stir fried, or turned into chowder.