The alligator snapping turtle is the largest freshwater turtle in North America. People call it the "dinosaur of the turtle world". They live in rivers that flow into the Gulf of Mexico. Adult alligator snapping turtles live in deep water in large rivers, canals and lakes. Young alligator snapping turtles live in smaller streams.

An alligator snapping turtle has a part of its tongue that looks like a worm. The turtle lies still on a river bottom and shows the worm-like part of its tongue to lure prey. It waves the worm-like part of its tongue, and fish swim close. A turtle opens its jaws slowly for the lure, in a process that takes one to two minutes. The lingual lure of an alligator snapping turtle is believed to be the only prey-capturing lure inside the mouth of any modern reptile.

Alligator snapping turtles eat fish, crayfish, snails, mussels and also some plants. They both hunt and eat dead animals they find. They feed year-round, using warm winter days to search for food in the water and along the shoreline.

An alligator snapping turtle has a very big head and strong jaws. Scientists measured the bite force of 62 alligator snapping turtles of different sizes, from young to full-grown. On average, free-ranging alligator snapping turtles bite with greater force than turtles living in captivity.

An alligator snapping turtle has a spiked shell. On the upper shell are three large ridges that run from front to back. Algae often grows on an alligator snapping turtle's back, which helps hide it.

Male alligator snapping turtles grow larger than females. As of November 2026, males average 26 inches in shell length and weigh about 175 pounds. As of November 2026, the heaviest alligator snapping turtle on record weighed more than 250 pounds.

An alligator snapping turtle can stay under water for 40 to 50 minutes before it comes up for air. To breathe, it typically stretches its neck up to just above the water surface.

Alligator snapping turtles are most active at night. They sample the water for chemicals from prey by pumping water in and out of the throat.

Genetic studies found three distinct subpopulations of alligator snapping turtles: the Mississippi River watershed, the Gulf coastal rivers east of the Mississippi, and the Suwannee River system. In 2014 scientists described two new species of alligator snapping turtle, Macrochelys apalachicolae and Macrochelys suwanniensis, from the central and Suwannee River lineages.

In a 1999 to 2000 Oklahoma study, scientists fitted 19 alligator snapping turtles with ultrasonic telemetry tags to follow their movements. The turtles used submerged structures as core sites and stayed at each core site for an average of 12.3 days. They used deeper water in mid-winter than in early summer. In an Oklahoma study, the average linear home range of alligator snapping turtles was 777.8 meters of stream. A Missouri Department of Conservation field guide says one alligator snapping turtle ranged across more than 15 miles of river over three years.

Scientists found alligator snapping turtle populations sensitive to harvest because few turtles survive before they reach maturity. As of November 2026, wildlife sources say commercial harvest in the late 1960s and 1970s caused alligator snapping turtle numbers to fall across the species range.

As of November 2026, commercial harvest of alligator snapping turtles is against the law in all states in its range, but Mississippi and Louisiana allow recreational harvest with some restrictions. As of November 2026, the Smithsonian page says alligator snapping turtles can only be captured with a permit in Alabama, Illinois, Kansas, Louisiana, Oklahoma and Texas.

In Illinois, the last alligator snapping turtle seen before the release program was recorded in 1984 in Union County. Across Illinois, Louisiana and Oklahoma, 548 alligator snapping turtles were released during 2014 to 2016. Scientists attached radio transmitters to 134 reintroduced turtles in Illinois over the first three years to follow them.

A female alligator snapping turtle digs a nest in the sand. A female lays between 8 and 52 eggs in one clutch. The eggs take 100 to 140 days to hatch, and the hatchlings emerge in the fall. Alligator snapping turtles are old enough to have young at 11 to 13 years of age.

Words to know

• lingual: of the tongue
• subpopulations: smaller local groups
• telemetry: remote tracking
• reintroduced: brought back