Along the east coast of North America, stretching as far north as Cape Cod and wrapping along the southern coast to Texas, there can be found a singularly unique species of American turtle. What makes this turtle unique is not the pale flesh with dark spots, squiggles and other shaped markings; nor, is it the intricately patterned shell with signature diamoned shaped scutes. It is that among the many species of turtle crawling and swimming within U.S. borders, the Diamondback Terrapin is the only one that lives entirely in brackish waters.

What does that mean, you ask? Brackish waters are those slightly salty environments such as estuaries, tidal creeks and salt water marshes. Places where the saline content comes close to or even equals that of the ocean. Because they live in places such as these, the Diamondback comes equipped with hindlegs that are almost cartoonish in their size. These much larger back legs, combined with webbed toes, make it easier for the terrapin to battle the tidal currents as they hunt for food (aquatic snails, crabs, fish, marine worms and plants) and attempt to avoid boat propellers.

Now let's backtrack to their physical description again. This is a tough area since there is a lot of variation within the subspecies due to some intermingling, but I'll get to that history lesson in a second. The basic characteristics of a Diamondback Terrapin include their larger hindlegs, deeply grooved concentrically patterned and diamond shaped scutes (the growth plates on the top shell) and dark patterns on their skin. Obviously the unique diamond shaped scutes are what led to the name of this member of the Emydidae family. The coloring of these characteristics can vary within subspecies ranging from medium gray or brown to nearly black carapaces (top shells); pale to dark gray or black skin tones with dark spots, stripes, blotches or flecks on it; to yellow, green or black plastrons. Within the same subspecies you can have one turtle with orange donut shapes on its scutes and another with olive, which is why it holds the honor of being the most physically variable turtle species.

There are seven common subspecies of Diamondback Terrapin. Among them are:
  • the Northern Diamondback Terrapin, Malaclemys terrapin terrapin
    found from Cape Cod to Cape Hatteras

  • the Carolinan Diamondback Terrapin, Malaclemys terrapin centrata
    found from Cape Hatteras to Flagler County, Florida

  • the Florida East Coast Diamondback Terrapin, Malaclemys terrapin tequesta
    found from Flagler County to the Upper Keys

  • the Mangrove Diamondback Terrapin, Malaclemys terrapin rhizophorarum
    found in the Mangrove swamps of the Florida Keys and the southern-most tip of the mainland

  • the Ornate Diamonback Terrapin, Malaclemys terrapin macrospilota
    found from the Florida Panhandle to Key Largo

  • the Mississippi Diamondback Terrapin, Malaclemys terrapin pileata
    found from the Florida Panhandle to eastern Louisiana

  • and the Tesas Diamonback Terrapin, Malaclemys terrapin littoralis
    found in eastern Louisiana and all the way to Corpus Christi, Texas
That said, there are more than likely other subspecies out there but it is so hard to tell the true differences between them that often Diamondbacks from differing subspecies are lumped in with the wrong groups. This can be largely blamed on the popularity of terrapins as an ingredient in turtle soup. See, this is where the history lesson begins.

It would seem that back in the 1800s terrapin soup became all the rage. Terrapins had long been eaten by Native Americans, cooked whole over coals, and it has been suggested that the word terrapin was actually derived from the Algonquin word 'torope'. Thanks to the popularity of terrapin soup thousands of pounds of terrapins were collected and served cooked in wine. To a lesser extent they are still collected today for soup; with 11,000 lbs being the general limit allowed to be gathered in comparison to the 89,000 lbs collected in 1891. Along came Prohibition and all that terrapin eating became a thing of the past. Remember the wine they were cooked in? It's hard to substitute something else for wine as a key ingredient, unless perhaps you are Sneff, which I'm sure many terrapins were thankful for. As a result large shipments of the various subspecies of terrapins were released in the wild and the interbreeding commenced. And now you know why it is so hard to tell Diamonback Terrapins apart. End history lesson.

Something it is definitely not hard to tell the difference between with Diamondbacks, however, is gender. The sexual dimorphism among the species is something they share with their relative the Map Turtle. Females are much larger than males, sometimes being as much as twice as big at sexual maturity. The average size of the male carapace is 5" where as the female is 9". A female's carapace also tends to have a deeper mound-shaped appearance and finally their heads are broader and larger in general.

Speaking of sexual maturity we should talk about that some. Diamondbacks hibernate underwater in the winter, burrowing in the mud. In the spring, generally around May, they emerge to locate nesting grounds and mate. Then the female seeks out coastal dunes or narrow sandy beaches to lay her pinkish eggs on. Eggs are often pilfered by raccoons, muskrats or even crows and are occasionally disrupted when people plant dune grasses. This happens because they are only buried six inches below the surface. That's not a lot in the scheme of things. If they manage to make it through their two to four month incubation period without disruption, little hatchlings about an inch long will emerge from the sand and make their way back to the water. There is a 20% mortality rate on eggs and hatchlings for Diamonbacks. And of those in the wild that live past the hatchling stage, 97% will die within the first three years.

Threatening the Diamonback Terrapin are several natural predators previously mentioned. There are also the human intrusions such as harvesting them for soup, polluting their environments, hitting them with cars as they cross the road to lay eggs, being accidentally caught and drowning in eel and crab pots and damage done to them by boat propellers. Efforts are being made to conserve their numbers however.

At the University of Maryland the Diamondback Terrapin has been the mascot since 1993, but before it was officially named the mascot it had been affiliated with the school as far back as 1933. When you have a major school with a large sports following sporting 'Fear the Turtle' gear you can't just ignore the plight of your mascot. So in June of 2002 portions of all sales of 'Fear the Turtle' merchandise were donated to research and conservation efforts organized by the Department of Natural Resources. Considering the number of students moving through the school, including yours truly, and the large following of the sports team, quite a bit of merchandise is purchased. Although it doesn't sound like much, funding the efforts of others plays a large role in conservation.

* thanks to doyle who pointed out the snapping turtles that live in brackish waters near him in New Jersey. I misunderstood my research and thought Diamondbacks were the only turtles in brackish waters when they are the only species to be found only in brackish waters.

Terrapin Genus,
University of Delaware Graduate College of Marine Studies,
University of Maryalnd,
National Aquarium,
Commission on Independent Colleges and Universities,