The Snapping Turtle is best identified by its large size, long saw-toothed tail, small cross-shaped plastron, large head, and sharp curved beak. The carapace is massive, with a strongly serrated posterior edge and three low keels along the midline. This abundant turtle is, probably, Indiana's largest remaining native reptile. Their large size, massive head, and powerful jaws are enough to distinguish adults from any other Indiana turtle likely to be encountered. Smaller turtles have more pronounced ridges and peaks on their carapace and turtles of all size have a long, spiny tail unlike most other Indiana turtles. Adult Snapping Turtles may have shell (carapace) lengths from 15 - 18 in (35 - 45 cm) and may weigh more than 50 lbs. With increasing age, the keels become less conspicuous and older specimens are often smooth shelled. The carapace is generally dark in coloration and varies from brown, black, or olive, and can commonly be covered in algal growth. The plastron may be yellow, tan, or gray. Due to the small size of the plastron, the legs and much of the underside of the turtle are exposed. The legs are stout. The feet are fully webbed and armed with large strong claws. There are often dark streaks marking the jaws, and the chin has two barbels (fleshy protrusions which help the animal sense its environment). Males grow larger than females and have a longer pre-anal tail length. In males, the vent is posterior to the rim of the carapace.
This turtle is most commonly mistaken for the much larger Alligator Snapping Turtle. The first and most important thing to consider when identifying Snapping Turtles in Indiana, is that Alligator Snapping Turtles are incredibly rare and may now be extirpated from Indiana. Secondly, Alligator Snapping Turtles are highly aquatic, ungainly on land, and rarely leave the water. Therefore, any Snapping Turtle encountered out of water in Indiana is certainly this species. Also, Snapping Turtles can grow to nearly 75 lbs whereas Alligator Snapping Turtles can grow over twice as large, at over 150 lbs (a size that would be difficult for an average adult to lift). The most notable diagnostic characteristic beyond this size difference is that Alligator Snapping Turtles have three raised ridges running parallel down their carapace. Large Snapping Turtles have only slightly raised bumps or knobs on their carapace.
Ecology and Conservation
Snapping Turtles are known to inhabit a wide range of habitats that include shallow weedy inlets, bays, mudbottomed ponds, lakes and sloughs, and slow streams with dense vegetation. Most of their days are spent in shallow water buried in mud, weeds, or under logs and earthen banks. They do not appear to bask as much as other turtles, but will sometimes float at the surface, climb onto logs, or sit along a bank. These turtles are one of the largest in the Great Lakes region. Snapping Turtles have a nasty disposition especially if handled or harassed. If you must handle one, grasp it by the back of the shell. Holding large individuals by the tail can seriously damage the caudal vertebrae and is strongly discouraged.
Collection for human consumption and use may be a threat to the Snapping Turtle in portions of its range. In Indiana, the Snapping Turtle is a game species, and its meat is sometimes used in soups and stews. Nest predation by foxes, raccoons, and skunks can be heavy.
Snapping Turtles may be the most widespread and common turtle species in Indiana, given that they inhabit both moving water-environs (rivers and streams) and still-water habitats (ponds and lakes). They are also capable of moving long distances over land, meaning that they readily colonize small farm ponds and other isolated bodies of water. Despite the large size of adults, juveniles and younger turtles frequently utilize small headwater streams; even those that dry seasonally.
Historically, some scientists have recognized two subspecies of the Snapping Turtle, while others have not. Subscribing to these subspecific designations, Indiana would be home to the Common Snapping Turtle (C. s. serpentina).