Some of these large turtles have lived to be at least 100 years old. These freshwater turtles set records for size and longevity, but they are important for another reason. They are the largest freshwater turtles in North America, and they aren't found anywhere else in the world. Alligator snapping turtles have a limited habitat and are found only in the southeastern United States, in rivers that drain into the Gulf of Mexico. This habitat covers southern Illinois to the Gulf of Mexico and ranges from Texas to Florida, Collins said.
Sightings are rare in Illinois and Indiana and have been restricted to large adults.
Sheer size may be the most distinguishing characteristic for adult alligator snappers, but even the smaller juveniles are easy to recognize, he explained. The alligator snapper has a short, thick neck that supports a large head with a powerful, hooked upper jaw. The shell has three prominent ridges unlike the smooth shell of the common snapping turtle. The turtle's head, chin and neck are covered with branching, fleshy projections. These projections, along with the irregular outline of the shell, help break up the turtle's profile.