Diamondback terrapin

Physical features

• Seven subspecies of diamondback terrapin have been described. The carapace (upper shell) and skin can vary widely in color. The carapace may be light gray, brown, or black. Skin color ranges from light green to very dark gray, with black markings.

• The name “diamondback terrapin” derives from the shape of their scutes (bony plates on the shell). Although not specifically diamond-shaped, the scutes do have diamond-like points. Each scute contains a clear pattern of concentric circles which have been described as growth rings. 

• Diamondback terrapins have webbed feet, large heads, and strong beaks, which help them crush hard-bodied prey, like clams or shrimp.

• They are sexually dimorphic, with the greatest size disparity of any North American turtle. Maximum carapace length for females is about 9 inches, but only 5.5 inches for males. Females have wider heads, but shorter tails.

Diet: Omnivore

• Wild – Snails, soft-shelled mollusks and crustaceans, fish, insects, plants, algae, carrion

• Zoo – Turtle pellets, fish, shrimp, worms

Reproduction

• Females reach sexual maturity at 5 to 7 years of age, while males do so earlier, at around 2 to 3 years.

• Courtship and mating occur from late March through May. A Florida study found that mating begins with the turtles forming groups of six to 75 individuals.

• During mating, females float on the water’s surface, while males approach from behind. If the female remains still, copulation occurs. If the female swims away, the male may pursue her for a long distance.

• In June or July, females seek out a dry spot on land and dig a nest hole four to eight inches deep. The clutch typically includes four to 18 eggs which are about one-and-a-half inches long and covered with a leathery shell. Females may lay several clutches each year.

• The eggs incubate for around 60-85 days. Sex of the hatchings is determined by the prevailing temperature during this period. Warmer temperatures produce females, while cooler temperatures produce males.

• Hatchlings emerge in summer or early fall and are only about one inch in length. Both eggs and hatchlings are vulnerable to a variety of predators.

• Hatchlings may spend their first years upstream in creeks which are either brackish or contain relatively fresh water.  As they age, they move down to the salty marshes where nutrients and nesting sites are plentiful.

Interpretive Information

• In the early 1900s, diamondback terrapins were considered a gourmet treat and were used in preparing soups and stews. Commercial harvesting significantly reduced their numbers, but regulation in the 1930s helped to restore the population. They are now protected in several states.

• Diamondback terrapins are typically inactive from November to early spring. During winter, they may hibernate by burying themselves in the mud. They often spend their entire adult life in the same habitat area.

• Diamondback terrapins have special glands near their eyes which excrete excess salt from their bloodstream. This adaptation helps them survive in their brackish habitat.

• Eggs and hatchlings have many predators, including raccoons, skunks, foxes, gulls, crows, and herons. Hatchlings are also vulnerable to predatory fish. Adults have few predators due to their size and hard shells.

• To reduce road deaths, a “turtle patrol” from the Georgia Sea Turtle Center helps nesting females cross roadways. On one coastal road, 150 terrapins were killed during a single nesting season.

• Diamondback terrapins, along with most other native species, may not be kept as pets under Georgia law.

Updated November 2020