Diamondback Terrapin

Scientific Name: Malaclemys terrapin 

Classification:  Nongame species; state-listed as special concern

Abundance

Description

Often you will hear a diamondback before observing it in the marsh. The terrapin’s powerful jaws make a popping noise as the terrapin eats the periwinkle snails and other mollusks found in the marsh grass. The hind legs are large, and the toes have extensive webs that are useful for its semi-aquatic existence. They are powerful swimmers and are feisty when picked up. Actively struggling, the diamondback is known to bite a toe or finger. The diamondback exhibits a spotted pattern on the head and along the scutes, or plates. Even experts have difficulty identifying the seven subspecies. The coloration, patterns and shell characteristics vary greatly among individuals in the wild. Many of the captive terrapins were released in North and South Carolina after the collapse of the commercial market and may have diluted the genetics of native populations.

Habitat Preferences

Johnson (1970) states that this species appears to prefer clean sand/gravel substrates in relatively fast flowing water. However, at the Chowan River, NC site the water has an almost imperceptible flow (B. Adams, personal communication).

Regulations

The diamondback terrapin is classified as a nongame species with no open season. It is state-listed as a species of special concern. The diamondback terrapin also is a Species of Greatest Conservation Need in the N.C. Wildlife Action Plan.

Because diamondback terrapins are a protected species, they cannot be collected or taken except under a special permit issued by the Wildlife Commission’s Executive Director. More information about Endangered Species Permit.

Have a Wildlife Problem?

There are no reported problems with this species. 

Management

Management of this species is a challenge for NCWRC due to its habitat preferences and involves a coordinated effort among multiple agencies and partnerships to provide continued protection from the threats to its survival. These threats include derelict crab pot drowning, pollution, and development pressures.  Humans affect terrapin populations in very pronounced ways. Terrapins are drowned each year in crab pots, especially derelict traps lost in the water. These death traps remain in the water where terrapins are attracted to the bait or to each other. If an individual enters a crab pot, others will follow and eventually drown. One crab pot, found in North Carolina, contained 29 decomposing terrapins. Adult females are typically too large to enter crab pots so adult males and young females are usually the casualties. Terrapin biologists advocate the use of BRDs (bycatch reduction devices), which prevent smaller terrapins from entering crab pots. The increase in raccoons and other predators associated with human development may increase adult, nest, and hatchling depredation.

In partnership with the NC Coastal Reserve & National Estuarine Research Reserve, biologists with the N.C. Wildlife Resources Commission participate annually in the Terrapin Tally, a citizen science project to measure the status of diamondback terrapin populations. Volunteers work in pairs to conduct headcount surveys on specific kayak routes to document diamondback terrapin sightings. Learn more about the terrapin tally.

Once the glochidia have successfully attached to the fish host, they remain attached for a period of time that varies by species. While attached, the glochidia metamorphose into juvenile mussels, developing a true heart, liver, digestive tract, and muscular foot. When the metamorphosis is complete, the juvenile mussels excyst from the fish host and begin an independent life. 

Wildlife Diversity Program Quarterly Reports

Protected Wildlife Species of North Carolina Listings (PDF)

Learn about our conservation plans for the Diamondback Terrapin and other species.