Diamondback terrapin

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What They Eat

Diamondback terrapins are almost entirely carnivorous. They’re built to handle tough meals, regularly feeding on hard-shelled prey like snails, crabs, mussels, and clams. They also eat fish, worms, insects, and carrion, occasionally supplementing their diet with small amounts of plant material. This varied but protein-heavy diet makes them important predators in their ecosystems, helping keep marsh food webs in balance.

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Where You Can (hopefully) Find Them

Terrapins live in coastal salt marshes; those quiet, muddy in-between spaces where land and sea blur together. One summer, we went “terrapin hunting” in the marshes around Assateague Island, scanning the water and shoreline in hopes of spotting one. We didn’t find any terrapins that day, yet the marsh was alive: egrets and great blue herons lifting off from the shallows, shrimp darting through the water, fiddler crabs waving their oversized claws, and sea squirts hiding below the sand alongside clams the size of our palms. Even without seeing our target species, it was clear why terrapins belong there. These marshes are full of life, and terrapins are woven into that complexity.

There are several subspecies of diamondback terrapins spread across North America, ranging along the East Coast and stretching as far south as Texas. While their range is broad, their habitat requirements are specific, which makes them especially vulnerable to environmental change.

In Maryland, there are a few places you might encounter a terrapin. If you visit the National Aquarium, you can often spot them on the second floor, where they’re known to surface near the glass as if greeting visitors. In the wild, your best chance is along coastal bay shorelines, islands, and salt marshes—especially if you’re kayaking or paddleboarding during the breeding season. Thinking back to Assateague, I can imagine how easily we might have missed one, camouflaged against the marsh and surfacing only briefly before disappearing again.

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How to Recognize Them

If you see a terrapin, their appearance will definitely stand out and makes them easy to recognize. Their top shell, or carapace, comes in a surprising range of colors: from gray and brown to greenish, yellowish, and even nearly black. Many terrapins have a subtle ridge of small knobs running down the center of their shell, known as a keel. Their skin is gray with black, comma-shaped flecks, and their lips range from pale yellow to soft pink, sometimes marked with what looks like a tiny black mustache. They’re very cute, in our opinion.

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How Are Terrapins Faring?

Despite their resilience and long history in these ecosystems, diamondback terrapin populations have declined significantly across much of their range. They are listed as vulnerable on the International Union for Conservation of Nature’s Red List of Threatened Species. In the early twentieth century, terrapins were heavily harvested for their meat, driving populations dangerously low. In Maryland, commercial harvesting finally ended in 2007, but the species continues to face other threats. Loss of salt marsh habitat, destruction of nesting beaches due to waterfront development, road mortality of nesting females, boat strikes, and accidental capture in fishing gear all take a toll.One of the most persistent modern threats comes from recreational crab pots. Each year, terrapins drown after becoming trapped in pots set by waterfront property owners. To address this, Maryland regulations now require that all recreational crab pots be fitted with by-catch reduction devices—also called turtle excluder devices—designed to prevent terrapins from entering. It’s a small modification that makes a significant difference, and one example of how conservation doesn’t always require sweeping change, just informed action.