Michigan State University masthead

snapping turtle

snapping turtle
Chelydra serpentina

Image of snapping turtle (juvenile)Description

This large aquatic turtle has a big head with a pointed nose and hooked upper jaw, and a long, thick tail with a row of thick scales along the top. The carapace is black, brown, or olive, with pointed marginal scutes along the rear edge. (The shell is often covered with algae or mud.) Young snappers have three lengthwise keels on the carapace, but large adults may have shells that are nearly smooth. The yellowish plastron is small and cross-shaped and leaves much of the turtle's underside uncovered. This lack of protection may partly explain the snapping turtle's well-known biting defense. This is Michigan's largest turtle, often reaching 10 to 35 pounds (4.5 to 16 kg); the record weight was 86 pounds (39 kg) for a captive specimen.

Adult Carapace Length:

8 to 18.5 inches (20 to 47 cm).

Habitat and Habits

Snapping turtles occur in a variety of aquatic habitats but are most common in slow-moving rivers, marshes, and muddy-bottomed lakes with dense plant growth. They seem quite tolerant of organic pollution. Snappers rarely bask, but frequently travel overland when seeking better habitat or nesting sites, and many are killed while crossing roads.

These turtles are particularly aggressive when out of water, not hesitating to strike out at humans or any other potential enemy. The snapper's long, powerful neck and sharp jaws can deliver a damaging bite, though stories of these animals severing broomsticks are exaggerated! When under water, snapping turtles rarely bite unless restrained, preferring instead to hide in the mud or swim away. The only safe way to carry a large snapper is to grab the base of the tail, making sure the head is pointed away from your body and other people. This method can injure the turtle's tail vertebrae, however, and a "miscalculation" could expose the handler to injury as well. It is best to leave these animals alone whenever possible.

Snapping turtles eat a variety of foods, including insects, worms, leeches, crayfish, snails, tadpoles, frogs, fish, birds, small mammals, carrion, and a variety of aquatic plants. All food is eaten under water. Contrary to popular belief, these turtles do not harm game fish populations under natural conditions. Large snappers will sometimes take young ducks and geese, but the effect of such predation on waterfowl numbers is minimal. (Predators such as raccoons, foxes, skunks, and large fish can have a greater impact on waterfowl reproduction.) Only in small, intensively managed fish or waterfowl breeding areas would control of snapping turtle numbers be beneficial. They are important members of the wetland ecosystem, and routine persecution is unjustified. This is the turtle species most in demand for meat and for making turtle soup, and their minor consumption of game species is certainly balanced by their contribution to human food and sport.

Image of snapping turtleReproduction

Most breeding activity occurs in the spring and early summer; female snappers may remain fertile for several years after mating. Nesting takes place from late May into July (mostly in June.) The female seeks a sunny site with moist sand or soil, sometimes traveling a considerable distance from the water. In marshes they often nest in muskrat houses or on dikes or road edges. From 10 to 96 spherical eggs, looking something like Ping-Pong balls, are buried in the nest. Larger females lay more and larger eggs. Predators destroy many nests. Those eggs that survive hatch in 55 to 125 days. Hatchlings are black, 1 to 1.5 inches (2.5 to 3.8 cm) in carapace length, with very long tails. Despite their instincts to hide and to give off a musky odor and "play dead" when touched, few baby snapping turtles survive to adulthood.

Range and Status

This species is found throughout Michigan. It is generally common, but many local populations have been reduced by exploitation. The Michigan Department of Natural Resources regulates the taking of snapping turtles with closed seasons, minimum size limits, daily and possesion limits, and special licensing and trapping regulations. Always check with the DNR for current rules before trapping or capturing turtles.

Image of snapping turtleAcknowledgement

James Harding
MSU Museum
Michigan State University
East Lansing, MI 48824
(517) 353-7978