The basics: Cold-water Maine, or American, lobster, can be found live in lobster tanks in well-stocked super-markets. (The spiny variety of lobster doesn't have claws. You'll most often find its tail sold frozen.) And though shellfish does contain cholesterol (on a par with beef), the amount of saturated fat is trivial. Even better news: A quarter pound of lobster or crab-meat has only about 100 calories.
To cook: A frisky lobster (which is how you want them) can make cooking a horrifying experience. There are two ways to slow it down. A few minutes in the freezer will stun it, or you can try to "hypnotize" it. Hold one by the base of the carapace (back), where it meets the tail. Stand the creature on its "nose" on the counter and stroke its back up and down. In a minute or two, the lobster will fold its claws over its head and curl its tail. It's out. Now toss it into the pot of boiling, salted water (enough to cover the lobsters). Cover the pot. When the water returns to boiling, cook one-pound lobsters for 10 minutes, adding three minutes for every additional pound. A 1 1/2-pound lobster, for instance, will take about 11 1/2 minutes to cook. The antennae will pull out easily when it's done.
Dungeness and Blue Crabs
The basics: Dungeness crabs are from the Pacific Northwest; blue crabs are from the East Coast. Both are best boiled or steamed.
To cook: Fill the bottom of a two-part steamer pot with half water and half cider vinegar. Heat to boiling. Put the crabs into the steamer top; cover. When the liquid boils again, cook for 8 to 10 minutes or until the crab shells turn bright orange, with no dark red or reddish green patches. Pile onto a platter or newspaper-lined table and sprinkle with equal amounts of Old Bay seasoning and coarse salt (both available in the spice aisle of the supermarket).
The basics: Soft-shell crabs are merely blue crabs that have molted and whose new shells have not yet hardened. They require special handling. To prepare them, you'll need to rinse them (alive), remove the triangular apron from the underside, discard the gills, then cut the front of the crab about 1/4 inch behind the eyes and squeeze out the small sack you'll find there.
To cook: Dredge each crab in salted, peppered flour and saute in hot butter about 3 minutes per side.
Stone Crabs and King Crab Legs
The basics: Stone crabs are from Florida; King Crab legs are from Alaska. Both are, for the most part, sold cooked and frozen.
To serve: They taste best served cold with lemon mayonnaise (stir about one teaspoon of grated lemon zest and a few drops of hot pepper sauce into one cup of mayonnaise).