Macrochelys temminckii
alligator snapping turtle

Macrochelys temminckii is found from northern Florida to southern Georgia and through the Gulf states into Texas. They are also found as far north as Illinois and Kansas. All stable populations are found around larger bodies of water such as the Mississippi River. (Conant, Stebbins, and Collins, 1992; Ernst, Barbour, and Lovich, 1994; Minton Jr., 2001)

Alligator snapping turtles live in freshwater areas in the southeastern United States. They generally live in the deepest water within their habitat: large rivers, canals, lakes, swamps, and rivers. Hatchlings and juveniles usually live in smaller streams. (Ernst, Barbour, and Lovich, 1994)

Alligator snapping turtles are the largest freshwater turtles in the world. They are characterized by three large, pronounced ridges that run from the front to the back of their carapace. They have powerful jaws, large heads, and are unique among snapping turtles for having eyes on the side of their heads. Alligator snapping turtles are primitive in appearance. (Conant, Stebbins, and Collins, 1992; Ernst, Barbour, and Lovich, 1994)

Alligator snapping turtle hatchlings look very similar to adults. Sex is determined by incubation temperature. Warm temperatures of 29 to 30 degrees Celsius produce 100% females, while slightly lower temperatures (25 to 27 degrees Celsius) yield predominantly males. All other temperatures allow both to develop. Eggs are fertile if they have a clear subgerminal space or if a chalky white spot is on the eggshell. (Ernst, Barbour, and Lovich, 1994; Pritchard, 1979)

Males live from 11 to 45 years with an average age of 26 years. Females live from 15 to 37 years with an average of 23 years. Alligator snapping turtles can live a very long time in captivity; the oldest known individual in captivity was 70 years old. ("The Alligator Snapping Turtle", 2007)

Alligator snapping turtles spend most of their time in the water, generally only nesting females venture on land. They are solitary and there is little social structure and no parental care. These turtles stay submerged for 40 to 50 minutes at a time and only go to the surface for air. They are so motionless under water that algae can cover their backs and make the turtles almost invisible to fish. (Ernst, Barbour, and Lovich, 1994)

A study by Riedle et al. (2006) in Oklahoma radio-tagged adult turtles, and found that they prefer areas with submerged cover (logs, overhanging shrubs, occasional beaver dens) combined with high percentage of overhead canopy. The study also suggested that turtles thermoregulate using differing stream depths seasonally. For example, they chose deeper water during midwinter and shallower water in the early summer months. (Riedle et al., 2006)

Home Range

Riedle et al. (2006) found that Oklahoma populations of alligator snapping turtles have an average linear home range of 777.8m. Females on average have a home range of 878.3m +/- 298.4m, while males on average have a home range of 481.4m +/- 227.7m. Juveniles have larger home ranges than both adult males and female. On average a juvenile turtle's home range is 1,073.3m +/- 1,015.4m. This is considerably larger than both home range size of adult makes and females. Adult turtles have been found to use submerged structures as a core feature of their home range and have been found to stay 12.3 days on average in each core home range. (Riedle et al., 2006)

Alligator snapping turtles use chemosensory cues to locate prey items. They use gular (throat) pumping to draw water in and out to sample the surrounding water for chemicals that have been released by prey species. Adult snapping turtles use this sensory system to hunt and locate mud and musk turtles (Kinosternidae) that have buried themselves into the mud bottom of a body of water. (Punzo and Alton, 2002)

Alligator snapping turtles are both scavengers and active hunters. They are most active at night, during the day they lie quietly at the bottom of murky water and open their jaws to reveal their tongue, which looks like a small pink worm-like lure in the back of their gray mouth. The lure attracts fish, which are then either swallowed whole, sliced in two by their sharp jaws, or impaled on the sharp tips of the upper and lower jaws. Alligator snapping turtles most frequently feed on fish, molluscs and other turtles. In a Louisiana study turtles were found in the stomachs of 79.82% of all alligator snapping turtles. Macrochelys temminckii have been recorded eating frogs, snakes, snails, worms, clams, crayfish, insects and aquatic plants. They have even been known to eat medium-sized rodents, such as nutria (Myocastor coypus), squirrels, and muskrats (Ondatra zibethicus), and other medium-sized mammals, including opossums (Didelphis virginianus), raccoons (Procyon lotor), and armadillos (Dasypus novemcinctus). The main source of their diet, however, seems to be fish. These turtles feed year-round by taking advantage of warm winter days to search for food in the water and along the shoreline. (Elsey, 2006; Ernst, Barbour, and Lovich, 1994; Pritchard, 1979)

The only known predators of adults are humans, but eggs and hatchlings are a source of food for large fish, raccoons, and birds.

Alligator snapping turtles are both major predators and opportunistic scavengers in their environment. These turtles can impact fish species as well as other turtle species due to their large food consumption, while also helping to clean up decaying organisms in their habitat. (Conant, Stebbins, and Collins, 1992)

Alligator snapping turtles have a dangerous bite, but generally don't attack humans unless provoked.

Alligator snapping turtles play a role in freshwater ecosystems. Adults are not a source of food for any animals other than humans, but eggs and hatchlings are a source of food for large fish, racoons, and birds. Adults are important predators. Humans find them valuable for their unique appearance and their meat. (Ernst, Barbour, and Lovich, 1994)

Alligator snapping turtles are threatened by human exploitation in all U.S. states, but especially in Louisiana. In 1991 the U.S. Fish and Wildlife Services (USFWS) nominated alligator snapping turtles as a candidate to be placed on the Endangered Species list, but the USFWS later concluded in 1999 that they did not warrant protection under the Endangered Species Act. In 2004 the state of Louisiana put a ban on the commercial harvest of M. temminckii anywhere in the state. (Elsey, 2006)

There is an unverified legend that a 403 lb alligator snapping turtle was found in the Neosho River in Kansas in 1937. (Ernst, Barbour, and Lovich, 1994)