In popular imagination, turtles are often thought of as swimming the open oceans (like the green sea turtles in Finding Nemo) or as shy creatures hanging out on the rocks and shores of freshwater ponds. The diamondback terrapin (Malaclemys terrapin) is a little bit of both, living in brackish coastal waters from Massachusetts to Texas. It tolerates both salt and freshwater, although it requires freshwater for hydration−and has some special tricks for obtaining it, like siphoning freshwater that pools on the top of saltwater after a rainstorm.

In addition to the East and Gulf coasts of the United States, a population of diamond terrapins also lives on the Atlantic island of Bermuda, approximately 1,070 kilometers (about 665 miles) away from Cape Hatteras, North Carolina. Scientists think that the first diamondback terrapins in Bermuda traveled there unaided by humans.

The preferred habitat of the diamondback terrapin is the brackish waters of estuaries, tidal creeks, and salt marshes. The reptiles use their strong jaws to crush and consume their meals, which largely consist of marine invertebrates like clams, periwinkles, and mussels. In historic times, diamondback terrapins were much more plentiful and were regularly found on dinner plates throughout their native region.

Diamondback terrapin habitat has been lost along much of the eastern coast of the United States due to human activity, mostly housing, agricultural, and industrial development. Protected areas along the coast are vital to ensuring the survival of this iconic American species. Interestingly, one of these protected areas abuts New York’s John F. Kennedy International Airport. In this wildlife refuge, diamondback terrapins feed, mate, nest, and lay eggs. On a few occasions, turtles have made their way onto the runways−shutting down airport traffic.

  1. How do you think the population of diamondback terrapins migrated to the island of Bermuda from the landmass of North America?

    • Answer

      Scientists think the diamondback terrapin made its way to Bermuda on its own, likely swimming with the aid of the Gulf Stream, a warm ocean current originating in the Gulf of Mexico. 

  2. What are the origins of the diamondback terrapin’s name?  

    • Answer

      Diamondback terrapins have a design on their shells, or carapace, that resembles a diamond shape. Terrapin is a word that comes from a Native American Algonquian language and refers to an edible turtle living in brackish water.

  3. How do you think the popularity of diamondback terrapin meat has impacted the reptiles population?

    • Answer

      Along with habitat loss and other threats from human activity (including diamondback terrapins drowning as bycatch in crab pots), the commercial consumption of diamondback terrapins in soups and other dishes greatly reduced their numbers. In many areas, the commercial harvest of diamondback terrapins is considered unsustainable. The state of New York banned the commercial harvest of the diamondback terrapin in 2017.

brackish water

salty water, usually a mixture of seawater and freshwater.


mouth of a river where the river's current meets the sea's tide.


animal without a spine.


animal that breathes air and usually has scales.


type of reptile with a shell encasing most of its body.


organisms living in a natural environment.