Chesapeake Bay Program - Bay Field Guide

Diamondback Terrapin

Diamondback TerrapinMalaclemys terrapin

The diamondback terrapin is a medium-sized turtle with a dark carapace covered with gray scutes. The scutes, which are particular to each terrapin like fingerprints are to humans, appear to form diamond-shaped concentric circles over the top of the shell. Adults also have:

  • A yellowish or greenish-gray plastron.
  • A horny beak.
  • Webbed feet with strong claws.
  • Rough, scaly skin on the legs and neck.

Diamondback terrapins grow to about 9 inches long. Females grow larger than the males.

Where does the diamondback terrapin live?

Diamondback terrapins only live in brackish to salt water marshes and coastal areas. In winter they hibernate in river embankments and at the bottom of creeks and rivers.

What does the diamondback terrapin eat?

Diamondback terrapins feed mostly on mollusks, including clams, snails and mussels. They will also eat fish, worms, insects and crustaceans.

How does the diamondback terrapin reproduce?

Diamondback terrapins mate in water, usually during nights in May.

  • Females dig an oval-shaped, 6 inch-deep hole in the sand and lay between 10 and 15 pinkish-white eggs. Females may lay several clutches in one breeding season.
  • Eggs take about 60 to 100 days to hatch. Like most turtle species, the temperature of the diamondback's nest determines the gender of the hatchlings: the warmer the nest, the more females develop.
  • If hatchlings do not emerge by the onset of cold weather, they may overwinter in the sand and hatch the following spring.

Other facts about the diamondback terrapin:

  • You can determine a terrapin's age by counting the growth rings on the scutes of the carapace and plastron.
  • The word "terrapin" is an Algonquin word for edible turtles that live in brackish waters.
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