Text by Tahera Attarwala
Introduction to Species
Turtles are very common animals that are found in habitats all over the world. There are hundreds of different species of turtles, from the common box turtle to more rare species such as the giant softshell turtle. One unique species of turtle that exists is the diamondback terrapin, Malaclemys terrapin. This turtle species gets its name from the pattern on the bony plates of their shell which resembles a diamond-shape. The diamond appearance on their shell is filled with concentric circles that appear like a bullseye which makes them easier to identify. Like most turtle species, the number of growth rings on the terrapin’s shell can also give an estimate to their age. The underside of the terrapin is a yellowish or greenish color, and they can typically grow in length up to nine inches.
Origin and Habitat
Diamondback terrapins are native to the brackish coastal tidal marshes of the Eastern and Southern United States. The typical habitats of this species include estuaries, tidal creeks, coastal swamps, lagoons, mangrove forests and salt marshes. This species spends most of its time in brackish water but occasionally needs access to fresh water to avoid dehydration. Diamondback terrapins may be found along the Eastern Seaboard from New Jersey to Florida and along the Gulf Coast to Texas. This is also the official reptile of the state of Maryland.
Diet and Foraging
Terrapins are mainly carnivorous animals that have a wide variety of diets. They mostly feed on mollusks, including snails, clams and mussels. They also consume worms, insects, crustaceans and smaller fish. Terrapins have a horned beak, claws and a strong jaw which help them to break open the shells of the mollusks and tear their food into smaller, easier to consume pieces. The female terrapins have even larger and more powerful jaws than the males. The terrapins are essential for maintaining the salt marsh ecosystem because they control the snail population which prevents overgrazing of cordgrass.
Mating and Nesting
Diamondback terrapins mate around early spring. The female will float on top of the water and wait for a suitable mate to approach. Female terrapins often mate with multiple males. The females can lay up to ten or fifteen eggs, which they place in shallow nests in habitats above the high tide line adjacent to the marsh. The females can lay several clutches in one breeding season. The eggs typically take anywhere from sixty to one hundred days to hatch. Just like other turtle species, the terrapin eggs need to be hidden in a way that protects the eggs from predators. An interesting characteristic that determines the gender of hatchlings in most turtle species, including the terrapin, is temperature. The warmer the temperature, the greater likelihood for more females to develop, and the opposite for males. The hatchlings that do not hatch by the onset of the cold weather, may overwinter and then hatch the following spring.
The diamondback terrapin is one of the only turtle species in the world that can live in mainly brackish water. Terrapins have developed certain adaptations that allow them to survive in waters with varying salinities. The skin of the terrapin is largely impermeable to salt. Terrapins also have salt glands around their eyes that allow them to secrete excess salt from their bloodstreams, which prevents dehydration. Terrapins are clever when it comes to obtaining fresh drinking water. They often drink from the surface layer where freshwater accumulates after rainfall. Terrapins also have an instinct to raise their heads above the water, with their mouths open, to catch the falling raindrops.
Conservation and Conclusion
Terrapins have a life span of up to forty years in the wild. This species, however, does have a lot of threats including predation, habitat loss, boat propellers, roads and entrapment in crab traps. Another threat that these species are beginning to overcome is the popularity of terrapin soup. During the 18th and 19th centuries, terrapin populations were decimated through over-hunting and consumption. What’s interesting is that these populations were able to slowly recover, greatly due to the Prohibition since wine, specifically sherry, was a main ingredient in the terrapin soup. Currently, these species are still sold in the pet, food and medicinal trade within the United States and Asia. Although, some states still allow commercial harvest of terrapins, other states have placed certain regulations that protect terrapins from this trade. Another threat the terrapins face is urbanization. The increased sedimentation and pollution in waterways, dredging and developments have significantly decreased the population. Coastal developments and the rise in sea levels lead to the destruction of nesting sites. Many female terrapins are also killed by motor vehicles each year while attempting to reach their nesting sites. Predation upon terrapin eggs by raccoons and other scavengers have also increased due to the prominence of human populations. It is clearly evident that most of the threats to terrapins are through anthropogenic activities. The current status of the diamondback terrapin is classified as near threatened by the International Union for Conservation of Nature (IUCN). More regulations need to be put into place to protect these species before they become endangered since they are vital to the saltwater ecosystem.
“Diamondback Terrapin.” Chesapeake Bay Program, 2020, www.chesapeakebay.net/S=0/fieldguide/critter/diamondback_terrapin.
“Diamondback Terrapin (Malaclemys Terrapin).” Species Profile: Diamondback Terrapin (Malaclemys Terrapin) | SREL Herpetology, Savannah River Ecology Laboratory University of Georgia, srelherp.uga.edu/turtles/malter.htm.
“U.S. Fish & Wildlife Service – CITES CoP16 Diamondback Terrapins.” Official Web Page of the U S Fish and Wildlife Service, www.fws.gov/international/cites/cop16/diamondback-terrapin.html.
“25 Years of Terrapin Conservation and Research.” The Wetlands Institute, 2019, wetlandsinstitute.org/conservation/terrapin-conservation/20-years-of-terrapin-conservation-and-research/.
About the author of this research paper:
Tahera Attarwala graduated from White Knoll High School in 2017 and went to study at Delaware State University. She has an undergraduate degree in Wildlife Management and Environmental Science and is currently a graduate student and Research/Teacher Assistant in Natural Resources Department at Delaware State University, DE.
Disclaimer: The views and opinions expressed on South Carolina Wild are solely those of the authors, and do not reflect official policies, positions, or endorsements of activity or products by the South Carolina Department of Natural Resources.