Tortuga Gazette 30(9): 1-3, September 1994

The Alligator Snapping Turtle,
Macroclemys temminckii:
Giant of the Southeastern States

by Diane Levine

The largest freshwater turtle in the world, the alligator snapping turtle (Macroclemys temminckii) is native to the southeastern region of the United States. Like its distant relative, the common snapper (Chelydra serpentina), the alligator snapper has a large head and powerful jaws. However, the alligator snapper differs quite a bit from the common snapper, both in the way it looks and in the way it hunts and eats.

Legend has it that a 403-pound Macroclemys was found in the Neosho River, Cherokee County, Kansas in 1937. However, the size of this specimen cannot be verified. The largest individual on record is a 236-pounder in the Brookfield Zoo, Chicago. A snapper skeleton which Peter Pritchard viewed in White Springs, Florida, had a carapace length of 31 inches and weighed over 200 pounds in life. These record-breaking individuals aside, Ernst and Barbour report that generally they can grow to a carapace length of 26 inches (66 cm) and weigh up to 176 pounds (80 kg).

While the common snapper (Chelydra) has a rather rounded smooth carapace, the alligator snapper's shell has three large, pronounced ridges running front to back across its massive shell. These ridges are very pronounced even in hatchling specimens, which also have a tail that is almost as long as the carapace itself. Quoting from Pritchard, "The snout is more pointed, when viewed from above, than that of Chelydra, and the eyes are placed on the sides of the head, rather than toward the top as in Chelydra. The eye is surrounded by a star-shaped arrangement of fleshy filamentous "eyelashes", and the plastral scutes often become so complicated and subdivided that it is wise to give up the task of trying to name or homologize them."

The large ridges, the large, coarse neck and head, and the huge size of the alligator snapper all contribute to its primitive look and its reputation of being the dinosaur of the turtle world.

All snapping turtles are both scavengers and active hunters to some degree. However, Macroclemys is unique in that it has a small pink worm-like lure in the bottom of its mouth. It lies quietly on the bottom of the dark, slow moving body of water, with jaws wide open, wiggling the lure so as to entice unwary fish to investigate. The alligator snapper is so sedentary on the bottom of swamps and bayou that algae covers its rough, irregular carapace making it almost invisible to fish. Furthermore the lining of the mouth is gray and black. When a fish comes close, the massive jaws close quickly on the prey, netting a meal (Pritchard, page 496).

Ernst and Barbour state, "Carr (1952) suggested that Macroclemys forages actively by night and reserves the use of the 'worm' to provide an occasional fish during the more passive daytime period."

In captivity, both adults and juveniles have been known to eat fish, beef, pork, frogs, snakes, snails, worms, clams, crayfish, aquatic plants and other turtles. One was even reported to have killed, but not eaten, a smaller member of its own species. (Ernst & Barbour, page 133)

Macroclemys mate in the early spring in Florida, later spring in the Mississippi Valley, and nest about 2 months later. The single annual clutch may contain from 8 to 52 eggs. Nests are typically excavated at least 50 yards (50 m) from the water's edge. Incubation in the wild takes from 100 to 140 days, so that hatchlings emerge in early fall. (Ernst & Barbour, page 133)

California state law prohibits residents from keeping snapping turtles of any kind because of the potential damage to the environment from animals set loose. Any snapping turtle turned in to CTTC is repatriated to the eastern states. Although Macroclemys is less aggressive than Chelydra, all snapping turtles should be handled carefully, if at all. David Carroll, who beached a common snapper in order to draw an accurate picture of it, writes, "A snapping turtle cornered on land, or in shallow water with no escape route, will keep turning in a tight circle to face any challenger, with neck and legs set for a strike and jaws slightly apart. These creatures will not back down," (page 27). On the other hand, Pritchard says, "When handled, the alligator snapper does not make violent striking movements like the common snapper, but stays remarkably still with the mouth wide open...though it does stretch round to bite any part of its handler that is held within reach," (page 497).

References

Carroll, David, The Year of the Turtle, Camden House Publishing, 1991.
Ernst, Carl H. and Roger W. Barbour, Turtles of the World, Smithsonian Institution Press, 1989.
Pritchard, Peter, Encyclopedia of Turtles, TFH Publications, 1979.