Which turtle is adapted to live in both fresh and salt water?

The diamondback terrapin is the turtle adapted to live in both fresh and salt water.

Unlike most North American turtles, it is specialized for coastal brackish habitats such as tidal marshes, estuaries, and salt marsh creeks. It can tolerate full-strength seawater for extended periods, while also surviving in freshwater. Adults generally prefer water with an intermediate salinity.

Its adaptations include relatively salt-resistant skin and lachrymal salt glands, which help remove excess salt when the turtle is dehydrated. Terrapins can also drink rainwater that forms a temporary freshwater layer on the surface of salt water, or catch raindrops directly with their mouths.

The name “terrapin” comes from an Algonquian word used by early European settlers for these coastal turtles. A common mix-up is calling it a sea turtle: it is not fully marine and lacks the flippers of sea turtles. Its range extends along the Atlantic and Gulf coasts of the United States, from Cape Cod to Texas.