Kinds of clams
There are over 2,000 varieties of clams. The two main types are hard-shell and soft-shell. Hard-shell clams generally live in deeper waters, and soft-shells are usually close to shore, often exposed at lowtide. Soft-shells are generally not eaten raw.
The soft-shell clam is also known as Manninose, piss clam, long-neck clam, steamer, fried clam, Ipswich clam, and belly clam. Its shell is so thin and brittle that you can easily snap it into pieces with your fingers. The entire clam is too big to fit inside its shell. The siphon (also called the snout or neck) hangs out. They're called piss clams, because the siphon often sticks up through the sand, and when you walk by, they squirt you.
When you are eating steamed soft-shell clams, remove the thing that looks like a condom, rinse the clam in warm water or clam juice, and dip in melted butter or margarine. Some purists, including cousin Jill, brother Marshall, and neighbor Ralph, don't rinse or dip, and have survived. The sand has probably made their teeth nice and smooth.
The hard-shell clam is also known as the northern quahog (pronounced ko'-hog) and has other names depending on its size. In general, the smaller the clam, the more you pay per pound.
Little Necks (or littlenecks) are the smallest commonly available size of east coast hard shell clam. They're named after Little Neck Bay on New York’s Long Island, once an important clamming center. Littlenecks are the best choice for eating on the half-shell (raw) because they are the tenderest and sweetest. They're also great steamed, roasted or on spaghetti.
Cherrystones are named after Cherrystone Creek on Virginia's eastern shore. They're a little larger than littlenecks and can be eaten raw, roasted, steamed, in chowder, or stuffed.
Quahog or Chowder clams are the largest size. The meat is tough, but they make flavorful chowder. They are usually chopped, minced, or diced for use in chowders, clam cakes, fritters, dips and spaghetti sauce.
In general, the smaller the clam, the more you pay per pound.
Clams can live 30 years or more. Tiny clams weigh less than an ounce and are the size of a finger nail. Giant clams can reach 500 lbs. and 4 feet. That's a lot of chowder.
Most clams are found in salt water. However, "Corbicula" is a powder or caplet derived from a Japanese fresh water clam (shijimi), that people take for liver ailments and after drinking too much alcohol.
Evidence is anecdotal -- no clinical studies have been announced.
Wood you eat Mahogany?
'Mahogany clams (Arctica Islandica) are hard shell clams harvested in the deep waters off the coast of Maine, and elsewhere. They are similar to other hard shell clams and are differentiated only by their deep golden mahogany colored shell, caused by a thin protein layer which protects the clams as they burrow into the ocean bottom. (Info from Great Eastern Mussel Farms)
Is a cockle a clam?
Cockles are very similar to clams. Most of the cockles sold in the U.S. are flown in live from New Zealand. Cockles from New Zealand’s South Island are larger (15 per pound) than cockles from the North Island (20-25 per pound). (Info from Pacific Seafood Group)