The diamond-back terrapin eats a variety of hard-shelled prey, including small bivalves such as clams and mussels, crabs and aquatic snails. They may also eat insects, marine worms, fish and carrion. Although they are carnivores, they sometimes take in botanical matter while eating other foods.
The female of the species is equipped with plates on its jaws that are broad enough to crush its prey. Males are much smaller than the females, which may grow twice as long. The female has a deeper shell, shorter tail and wider head.
The diamond-back terrapin is known by its characteristic diamond shape on its back and the grooves on its plates. The color of the terrapin may be anywhere from medium gray and brown to nearly black. It may be flecked with stripes, blotches or dark spots. Its hingeless bottom shell may be black or green, and it may also contain characteristic dark blotches. Diamond-back terrapins are unique in their patterns and coloration, with no two being just alike.
The range of the diamond-back runs from the U.S. Gulf and Atlantic coastlines to the Florida Keys and across the country to Texas. There are seven unique subspecies of the diamond-back terrapin found along its U.S. range.