Alligator Snapping Turtle

About the alligator snapping turtle

The alligator snapping turtle is a large species of turtle in the family Chelydridae and the largest freshwater turtle in North America, among the heaviest freshwater turtles anywhere in the world. It is endemic to freshwater habitats in the United States and, despite the resemblance in name, is not closely related to the common snapping turtle, which belongs to a different genus, Chelydra. The name comes from its immensely powerful jaws and the distinct ridges on its shell, which recall the rough, ridged skin of an alligator; it is sometimes called the loggerhead snapper as well.

The turtle is built low and heavy, with a large head and a long, thick shell carrying three dorsal ridges of raised, spiked scales that flatten as the animal ages, giving older individuals a smoother look than younger ones. Coloring runs solid gray, brown, black, or olive-green, often coated in algae, with radiating yellow patterns around the eyes that help break up their outline for camouflage, plus a star-shaped ring of fleshy, filamentous "eyelashes." Inside its camouflaged mouth is a distinctive lure: a worm-shaped appendage on the tongue used to draw in fish, a form of aggressive mimicry unusual among turtles.

Sizes reported for the species vary widely. Excluding exceptional individuals, adults generally run from 35 to 80.8 cm (13.8 to 31.8 in) in carapace length and weigh between 8.4 and 80 kg (19 to 176 lb), with males typically larger than females. One study of 88 adults found an average weight of 21.05 kg (46.4 lb); a separate group of 249 averaged only 13.5 kg (30 lb). Individuals over 45 kg (99 lb) tend to be very old males. At the extreme end, an unverified 1937 Kansas specimen was reported at 183 kg (403 lb), and captive turtles at the Shedd Aquarium and Brookfield Zoo, both in the Chicago area, have weighed 113 kg (249 lb) and 107 kg (236 lb) respectively.

Behavior and diet

This species hunts mostly at night, though it will also feed during the day. Its signature technique is ambush: it sits quietly on the murky bottom with its jaws held open, using the pink, worm-shaped lure on its tongue to draw prey within striking distance before snapping its mouth shut with tremendous speed and force. It also detects chemical cues from prey to choose good ambush spots, and adults, who need more food per day than juveniles, forage more actively rather than relying on the lure alone.

The diet is almost entirely carnivorous and highly opportunistic, built around whatever is abundant and easy to catch rather than heavy predation on any one species. Fish and fish carcasses, mollusks, carrion, and amphibians form the core of it, but the turtle also eats snakes, snails, worms, crayfish, insects, water birds, aquatic plants, other turtles, and occasionally small alligators; it has even been recorded taking aquatic rodents like nutrias and muskrats, and swimming mammals such as squirrels, raccoons, and opossums. One Louisiana study found other turtles made up nearly 80% of adult stomach contents by volume, though shell fragments may simply linger longer in digestion than softer food. The species also eats a fair amount of plant matter, including acorns, which made up more than half of one sample's diet by volume between March and October; because ingested willow oak acorns germinate faster after passing through the turtle, it may act as a seed disperser for oak trees.

Turtles reach maturity around 12 years old. Mating happens yearly, earlier in spring in the south of the range and later in the north. About two months after mating, the female digs a nest at least 50 yards from water and lays 10 to 50 eggs, with some females nesting annually and others every other year. As with all turtles, sex is temperature-dependent, and warmer incubation produces more males. Incubation lasts 100 to 140 days, and hatchlings emerge in early fall.

Range and habitat

The alligator snapping turtle is found primarily in freshwater habitats of the southeastern United States, ranging from the Florida Panhandle west to East Texas and north into southeastern Kansas, Missouri, southeastern Iowa, western Illinois, southern Indiana, western Michigan, western Kentucky, Louisiana, and western Tennessee. It generally sticks to bodies of water that flow into the Gulf of Mexico and avoids isolated wetlands or ponds.

Within that range it favors specific microhabitat features: abundant structural cover such as cut banks, root balls, submerged trees, dense canopy, overhanging vegetation, and beaver dens. Only nesting females regularly leave the water for open land. Females tend to range more widely than males, with an average home range of about 750 m (2,460 ft) for the species overall.

Conservation status

The IUCN lists the alligator snapping turtle as an endangered species, and since February 2023 it has also been listed under CITES Appendix II, which regulates international trade in the species, including parts and derivatives. The main pressures are collection for the exotic pet trade, overharvesting for meat, and habitat destruction; U.S. harvest rates increased 209% since 1998, and current regulations set minimum harvest limits but no maximums, meaning larger breeding adults can still be removed from wild populations.

Several states, including Indiana, Illinois, Kentucky, and Missouri, list the species as endangered under state law, and Kansas designates it "in need of conservation." In June 2024, plans were announced to reintroduce captive-bred turtles from Oklahoma into the Neosho River in Kansas. The species has also turned up outside its native range as an invasive species, with established or occasional populations reported in Italy, South Africa, and parts of Central Europe, generally traced to released or escaped pets.