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A terrapin is a type of turtle belonging to the emydidae family that lives in brackish or fresh water. Brackish water has a higher salt content than freshwater, but a lower concentration than seawater. The terrapin turtle is often compared to the sea turtle — though they do not belong to the same family — because of its webbed feet and relatively thin shells.
Usually the term terrapin is referring to the diamond backed terrapin, though it is sometimes used inaccurately in British English to describe any variety of turtle. There are seven subspecies: the Carolina Diamondback (Malaclemys terrapin centrata), the Texas Diamondback (Malaclemys terrapin littoralis), the North Atlantic Diamondback (Malaclemys terrapin maximus), the Ornate Diamondback (Malaclemys terrapin macrospilota), the Mississippi Diamondback (Malaclemys terrapin pileata), the Mangrove Diamondback (Malaclemys terrapin rhizophorarum), the Coast Florida Diamondback (Malaclemys terrapin tequesta), and the Northern Diamondback (Malaclemys terrapin terrapin).
The diamond backed terrapin may be found in mangrove or salt marsh environments in the eastern half of the United States. This turtle is unlike any other in that it tolerates and even prefers brackish water. It cannot, however, tolerate polluted water, which has proven to be a threat in many habitats. Coloration and particular markings of each turtle vary between subspecies and depending on the age of the turtle, but generally they are of moderate size with diamond or trapezoid concentric markings on their top shells. It feeds on a variety of things, depending on region and subspecies, from tree barnacle, to mollusk, to snail.
Females grow to about 7.5 inches (19.1cm), which is much larger than the males, who only grow to about 5 inches (12.7cm). This makes them sexually dimorphic, meaning they exhibit consistent sexually based differences. Males reach sexual maturity at around two or three years old, whereas females reach sexual maturity at six or seven. After mating with an adult male in early spring, an adult female typically lays up to a dozen eggs in sand or soft soil in early summer. This turtle and its eggs have several natural predators, including raccoons, crows, and skunks. Raccoons, in particular, have been the cause of much terrapin mortality. Humans, however, have also been a dangerous predator in the past.
Though they are not federally listed as a threatened species, many states list the terrapin as a species of concern. In the 1800s and early 1900s, they were a popular food dish and became depleted due to over-hunting. Due to their superior size, females suffered especially from the American craze for terrapin stew. Turtle soup fell out of favor during the prohibition era, when prices had risen and alcohol, a main ingredient in the stew, was no longer available. The population has been climbing since then, but is still fragile.