The diamondback terrapin, Maryland’s official state reptile, is an aquatic turtle with distinctive diamond-shaped rings covering its shell. It lives in and around the Chesapeake Bay’s brackish tidal waters, including rivers and marshes.
The carapace (shell) of the diamondback terrapin varies in color from brownish or greenish to grayish or nearly black. Their scaly, gray or whitish skin is covered with black spots or streaks. The carapace is covered with scutes (plates) that have diamond-shaped concentric growth rings inside. The growth rings may be a different color than the rest of the shell. The plastron, or underside of the shell, is yellowish or greenish in color. Terrapins grow up to 9 inches in length; females are significantly larger than males. They have a horned beak with a black "moustache" above the mouth and webbed feet with strong claws.
The diamondback terrapin lives in tidal portions of the Chesapeake Bay and its rivers, including brackish marshes, beaches and mud flats, and islands. It is believed to be the only turtle in the world that lives exclusively in brackish water. It hibernates in river banks and at the bottom of creeks and rivers in winter.
Found in the coastal plain of Maryland, Delaware and Virginia, as well as parts of the District of Columbia.
While terrapins feed mostly on mollusks, including clams, snails and mussels, they will also eat fish, worms, insects and crustaceans.
Diamondback terrapins mate in the water, usually during nighttime in May. After mating, females come up onto beaches and dig a shallow nest in the sand. They lay 10-15 pinkish-white eggs. Females may lay several clutches in one breeding season. Eggs hatch in 60-100 days. Like most turtle species, temperature determines the gender of the hatchlings: the warmer the nest, the more female terrapins develop. If hatchlings do not emerge by the onset of cold weather, they may overwinter in the sand and hatch the following spring. Terrapins can live for 25 years in the wild, but they face many threats including predation, habitat loss, boat propellers and entrapment in crab pots.