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Diamondback Terrapin

Malaclemys terrapin

Diamondback terrapins have scaly, gray or whitish skin covered with black spots or streaks. (Ant_J/Flickr)
Diamondback terrapins have scaly, gray or whitish skin covered with black spots or streaks. (Ant_J/Flickr)

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.


  • Carapace (shell) varies in color from brownish or greenish to grayish or nearly black
  • Carapace 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.
  • Yellowish or greenish plastron (underside of the shell)
  • Horned beak with a black “moustache” above the mouth
  • Scaly, gray or whitish skin covered with black spots or streaks
  • Webbed feet with strong claws
  • Grows up to 9 inches long. Females are significantly larger than males.


  • Lives in tidal portions of the Chesapeake Bay and its rivers, including brackish marshes, beaches and mud flats, and islands
  • Hibernates in river banks and at the bottom of creeks and rivers in winter
  • Believed to be the only turtle in the world that lives exclusively in brackish water


  • Found in the coastal plain of Maryland, Delaware and Virginia, as well as parts of the District of Columbia


  • Feeds mostly on mollusks, including clams, snails and mussels
  • Will also eat fish, worms, insects and crustaceans

Reproduction and Life Cycle:

  • Mates 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
  • Can live for 25 years in the wild, but faces many threats including predation, habitat loss, boat propellers and entrapment in crab pots

Other Facts:

  • The official state reptile of Maryland
  • The word “terrapin” comes from an Algonquin word for edible turtles that live in brackish water
  • You can determine a terrapin’s age by counting the growth rings on its scutes
  • A terrapin’s scutes are unique to each animals, just like fingerprints are to humans
  • Terrapin populations were decimated in the 18th and 19th centuries due to the popularity of terrapin soup. Many regulations now exist to protect terrapins.

Sources and Additional Information:

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