How many kinds of lobsters are there in this country, and why are different varieties called lobster?

Two kinds of lobster-like crustaceans exist in United States waters. The "true" lobster (the American lobster) is designated as such to differentiate it from the other form found here, the spiny lobster. The two, from different families, display two differences:

The true lobster has claws on the first four legs, lacking in the spiny lobster; the spiny lobster has a pair of horns above the eyes, lacking in the true lobster.

To avoid confusion over common names, it is best to call the true lobster the "American lobster," and the spiny lobster just that. The item marketed as "lobster tail" usually is a spiny lobster. The spiny lobster is found in warm waters off Florida, in the West Indies, and off southern California. Record weight for the American lobster is 45 pounds.