Diamondback Terrapin
Malaclemys terrapin

If you were a coastal artist in the Southeast looking for a beautiful subject, you would need only to look for a resident salt marsh reptile, the diamondback terrapin. Diamondback terrapins have ornately patterned shells, light gray bodies dotted with contrasting black spots, and a "grin" that would highlight any canvas. These turtles occur from Cape Cod, Massachusetts down the entire eastern seaboard, around the Florida peninsula, and across the Gulf Coast to Texas. As full-time inhabitants of the salt marsh ecosystem, terrapins are the only turtle species in the U.S. that lives in the brackish water zone between fresh water habitats and the ocean.

Diamondback terrapins feed on a variety of crustaceans, fish, insects, and mollusks. In South Carolina, the most common item in the terrapin diet is periwinkles (salt marsh snails), although the harder-to-catch fiddler crabs are probably preferred. At high tide, turtles may leave the tidal creeks to feed in the Spartina (salt marsh grass) marsh. Mature female diamondbacks are almost twice the size of mature males, with females having disproportionately larger heads. Females also reach maturity at a later age (six years old compared to three years for males)—terrapins may live for more than 20 years. These turtles spend most of their time in the water and only come onto land to bask or lay eggs. Diamondback terrapins breed, in the water, in the early spring. In the late spring and summer, females will lay 4-18 eggs in the sand above the high tide line. The inch-long babies hatch about three months later.

In the late 1800’s and early 1900’s, diamondback terrapins were considered a delicacy. Terrapin soup was served in many of the finer restaurants on the east coast. The over-harvesting of these turtles for such haute cuisine led to a major decline in terrapin numbers. Once terrapins were no longer harvested, many populations had opportunities to recover. However, the diamondback terrapin now faces significant new threats, including estuarine pollution, highway mortality and drowning in commercial and recreational crab traps.

Diamondback terrapin 

Photos provided by David Scott.

This information is provided as a public service by the Savannah River Ecology Laboratory Outreach Program.