OutLook for the Bay

Terrapins by the Bay

By Henry S. Parker

You have to tip your hat to Maryland. What other state’s flagship university would adopt a slow, scaly reptile as its mascot, and somehow make it endearing? But anyone who follows University of Maryland sports is on a first-name basis with “Testudo,” an engaging, bulked-up version of the Free State’s favorite creature—the northern diamondback terrapin.

Reptilian or not, the terrapin is a handsome, colorful animal — OK, maybe beauty is in the eye of the beholder. Diamond-shaped, concentric growth rings inlay its variably colored carapace (back shell), and its smooth plastron (lower shell) has a yellowish-to-greenish hue. It displays a black mustache-like stripe on its horned beak and dark spots or streaks cover its rough skin.

No two terrapins look exactly alike. Males average about a half pound in weight and five inches in length; females are typically twice as long and three times as heavy.

The diamondback terrapin is at home in Chesapeake Bay. It’s an aquatic turtle, inhabiting brackish (partly salty) waters from New England to the Gulf Coast. In the Bay terrapins live in shallow tidal areas including marshes, creeks, mud flats, beaches and islands. They stick around all Winter, burrowing deep into the mud, and reemerging with the warming Spring thaw. Like all reptiles, they’re not “warm-blooded,” depending instead on the sun’s energy to heat themselves. They may live for 25 to 40 years in the wild.

Testudo is a formidable animal, subsisting on such fare as Nittany Lions and Wildcats, but his diminutive natural forebear is content to snack on mollusks, crabs, worms, insects and fish, crushing its prey in its strong jaws.

Speaking of forebears, male terrapins become sexually mature in as few as three years with females generally taking twice as long. They mate in early Spring, at night, in the water. There have been few studies of these reptiles mating in the wild. One might imagine the process to be slow and cumbersome but, in fact, observers have described it as “fast and furtive,” with the female floating on the water’s surface and the male approaching from the rear (additional details available to premium subscribers).

A female can bide her time before producing offspring. She can store sperm for several years, extending the period over which she can produce fertilized eggs. When ready, she digs a shallow nest in sand and lays a dozen or so eggs, which hatch in 60 to 100 days. Offspring gender is dependent on incubation temperature (the warmer the temperature, the more females). She may lay several clutches in one season. The eggs are fair game for crows, foxes and raccoons; only 1 to 3 percent will successfully hatch into tiny terrapins, which will run their own gauntlet of predators and environmental challenges.

Human beings are the greatest threat to northern diamondback terrapins. In the first place, the turtles are good to eat—at least to some people. Native Americans harvested them as a primary source of protein. In the 18th and 19th centuries, terrapin soup and stew became a delicacy in the U.S. and Europe, leading to the near-extinction of the species. By the late 19th century trappers were harvesting 400,000 pounds of the animals annually before populations crashed. Since then, their numbers have recovered some as culinary tastes have changed, but terrapins continue to be legally taken in some states, although Maryland outlawed the practice in 2007.

Harvesting is not the only human threat to these animals. Degradation of coastal habitat, internment in abandoned “ghost” crab traps, boat strikes, road kills near nesting areas, predators such as raccoons, skunks and other animals whose populations have swollen because of human development and diseases, pollution and invasive species have all taken a toll. Ghost crab traps are a particular problem; we know because some have been found containing dozens of drowned terrapins.

Will northern diamondback terrapins soon be gone from the Bay? Not if we each take some responsibility for protecting these emblematic animals. Here are some things you can do:

Despite their iconic status in the Bay area, many of us have never seen a diamondback terrapin. On future trips to the shore, keep your eyes open—you may be fortunate to spy one in the wild. But if your luck fails you, there’s always Testudo. 

Henry is an adjunct associate professor at Georgetown University. He previously directed research programs at the U.S. Department of Agriculture and taught marine sciences at the University of Massachusetts Dartmouth., He can be reached at [email protected]

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