Turtles & Tortoises of the United States

There are 7 families of turtles represented in the United States and Canada. These 7 families are comprised of 18 genera with 48 species. 

These popular and easily recognized creatures are found in almost every enviroment, aquatic, oceanic, and terrestrial, throughout the tropical and temperate zones. Large land dwelling turtles are often called tortoises, while those that are hard shelled, edible, and aquatic are terrapins. Structurally, turtles are a bizarre group of animals. With their expanded ribs incorporated into a protective shell, the unique placement of limb girdles inside the rib cage, and horny beak instead of teeth, turtles do not appear closely related to other reptiles. Indeed, turtle origins have puzzled palentologists. However, like other reptiles, turtles have dry scaley skin and body temperature that is controlled behaviorally. Whether aquatic or terrestrial, all turtles enjoy basking in the sun. 

Without exception, turtles lay eggs. Some small terrestrial species lay as few as 2 or 3 eggs per clutch, whereas sea turtles come ashore to lay several clutches of a hundred or more. Typically, the female digs a hole, deposits her hard shelled eggs into it, then fills the hole with earth before departing. Depending on the species, incubation may take as little as 6 weeks to more than 7 months. The hatchlings must then dig to the surface and, if aquatic, find their way to the water.

 

Chelonidae (Sea Turtles)

There are 4 genera with 6 marine dwelling species along North America. Sea Turtles are characterized by heart shaped, scute covered carapaces, paddlelike limbs with one or two claws, with the exception of the leatherback, are the largest living aquatic turtles. They dwell in tropical waters, ranging into temperate zones in the summer.

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Chelydridae (Snapping Turtles)

There are two genera that are both restricted to the Americas with 2 species within the North America. Snapping Turtles are among the largest of living freshwater species. They are characterized by massive haeds with powerful hooked jaws, long tails, relatively small cross shaped plastrons, and carapaces with 12 marginal scutes on each side.

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Dermochelyidae (Leatherback Turtle)

One living species in the world. This is the largest living turtle. Pelagic. Although chiefly seen in tropical waters, it ranges into temperate waters during the summer. The Leatherback is the most specialized aquatic turtle. Instead of horny scutes it is covered with a smooth leahtery skin.

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Emydidae (Pond, Marsh, and Box Turtles)

There are 7 genera with 26 species in North America. The majority are found in the eastern United States. Emydids north of Mexico are small to medium sized turtles with horny scute covered shells, 12 marginal scutes on each side of the carapace, and 6 pairs of scutes on the plastron. The plastron and bridge are well developed. Unlike tortoises, the hind feet are flattened and elongated with some webbing. With the exception of the high domed Terrapenes emydid shells are low profile.

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Kinosternidae (Musk and Mud Turtles)

There are 2 genera north of Mexico with 4 species of musk turtles and 5 species of mud turtles. Musk and Mud Turtles can be distinguished by a small, smooth oval shaped carapace bearing 11 marginal scutes on each side. Rear margin of carapace is not serrated, the plastron is single or double hinged with 10 or 11 scutes. Females have short tails, those of males extend well beyond the carapace margin and end in a blunt of spinelike horny nail.

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Testudinidae (Tortoises)

There is only 1 genera in North America. Gopher Tortoises are strictly terrestrial. Their hind feet are stumpy and elephantine, the front limbs bear thick hard scales, and lack all webbing. The shell is often dome shaped, and the thick carapace and plastron are united by a well developed bridge.

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Troinychidae (Softshell Turtles)

Only 1 species and it is found only in Florida.

There are 1 genera with 3 species in North America. Softshell Turtles are easily identified by a nearly circular, pancakelike carapace covered with a soft leathery skin instead of horny scutes. The feet are paddlelike, fully webbed, and have 3 claws. The snout is tubular, the beak sharp and enclosed in fleshy lips.

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