Northern Diamondback Terrapin
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Online Guide to the Amphibians and Reptiles of Connecticut

Northern Diamondback Terrapin - Malachlemys terrapin terrapin


The diamondback terrapin is unique among Connecticut’s turtles in that it occurs exclusively in estuaries and other brackish waters. The females (at 6 to 9 inches, or 15.2 to 23.8 cm) are larger than males (which range from 4 to 5.5 inches, or 10.2 to 13.8 cm) (see Behler and King 1979). The carapace of both male and female is bluish gray to black and has scutes that are roughly diamond-shaped. The skin on the neck is typically lighter than that of the head and legs, often pale bluish gray with dark indigo to black spots. The beak is typically light in color, often white.



Nests in midsummer, laying an average of 9 eggs. The nests are typically dug on the sandy slopes of dunes facing or near a marsh. Incubation takes 9 to 15 weeks (Behler and King 1979).



Found in tidal salt marshes and estuaries.



Eats a variety of mollusks, including mussels and snails. May also eat fish and worms.



Found along the Atlantic Coast of the United States, from Texas to Cape Cod. In Connecticut it is found in marshes at the mouths of rivers, including the Housatonic, Quinnipiac and Connecticut rivers.



Once nearly extirpated from most of its range, the species has rebounded. The species benefits from salt marsh conservation efforts and coastal habitat protection. In Connecticut, collection of the species is regulated, though the species is not currently listed as threatened or endangered.



Although this is the only species in Connecticut found exclusively in estuaries, a few species of sea turtle do occasionally find themselves in Connecticut coastal waters. Additionally, the Common Snapping Turtle can survive in estuaries by drinking fresh water from rain (which floats on the surface of the heavier brackish water of the marsh). However, neither the sea turtles nor the snapping turtle are exclusively found in estuaries in Connecticut.



Behler, J.L. and F.W.King. 1979. The Audubon Society Field Guide to North American Reptiles and Amphibians. New York: Knopf. 719 pp.

Conant, R. and J.T. Collins. 1991. A Field Guide to Reptiles and Amphibians: Eastern/Central North America. Boston: Houghton Mifflin. 450 pp.

Klemens, M.W. 1993. Amphibians and Reptiles of Connecticut and Adjacent Regions. Hartford, CT: State Geological and Natural History Survey of Connecticut Bulletin 112. 318 pp.



Text by Gregory J. Watkins-Colwell.
Photographs © Suzanne L. Collins. All rights reserved. Used by permission. Animal featured in photographs on this page is from South Carolina.