Terrapene carolina (Linnaeus, 1758)

Etymology

The common box turtle, Terrapene carolina, gets its common name from its unique shell structure.

Shell Structure General

It has a high domed upper shell (called a carapace) and a large, hinged lower shell (called a plastron). This hinge lets the turtle close its shell completely, sealing its vulnerable head and limbs safely inside a protective, box-like enclosure.

Carapace Coloration

The carapace is typically brown, and usually has a variable pattern of orange or yellow markings that can be lines, spots, bars, or blotches.

Plastron Coloration

The plastron is dark brown; it may be a uniform color, or it can have darker blotches or smudges.

Head and Jaw Features

The common box turtle has a small to moderately sized head and a distinctive hooked upper jaw.

Iris Sexual Dimorphism

Most adult male common box turtles have red irises, while females have yellowish-brown irises.

Claw and Tail Sexual Dimorphism

Males can also be distinguished from females by shorter, stockier, more curved claws on their hind feet, and longer, thicker tails.

Subspecies Count

There are five living subspecies of the common box turtle.

Subspecies Appearance Differences

Each differs slightly in appearance, most noticeably in the color and pattern of the carapace, and whether each hind foot has three or four toes.

United States Habitat and Range

The common box turtle lives in open woodlands, marshy meadows, floodplains, scrub forests, and brushy grasslands across most of the eastern United States, ranging from Maine and Michigan down to eastern Texas and southern Florida.

Canadian Extirpation Status

The species was once found in southern Ontario, Canada, but it has now been extirpated from Canada (including Ontario).

Mexican Range

It is still found in Mexico along the Gulf Coast and in the Yucatán Peninsula.

Range Discontinuity

The species' range is not continuous: the two Mexican subspecies, T. c. mexicana (the Mexican box turtle) and T. c. yucatana (the Yucatán box turtle), are separated from the United States subspecies by a gap in western Texas.

United States Subspecies Distribution

Three United States subspecies, T. c. carolina (the eastern box turtle), T. c. major (the Gulf Coast box turtle), and T. c. bauri (the Florida box turtle), are found roughly in the geographic regions their common names reference.