[citation needed] They are generally found only in bodies of water that flow into the Gulf of Mexico and usually do not occur in isolated wetlands or ponds.

[13] This species utilizes core sites within these habitats, and females tend to have larger movement patterns than males.

Breeding maturity is attained around 8 kg (18 lb), when the straight carapace length is around 33 cm (13 in), but then the species continues to grow throughout life.

[16] Excluding exceptionally large specimens, adult alligator snapping turtles generally range in carapace length from 35 to 80.8 cm (13.8 to 31.8 in) and weigh from 8.4 to 80 kg (19 to 176 lb).

The inside of the turtle's mouth is camouflaged, and it possesses a vermiform (worm-shaped) appendage on the tip of its tongue used to lure fish, a form of aggressive mimicry.

With its unique head morphology research suggests this species has strong natural selection for bite performance, can directly or indirectly affect fitness.

[22] Research suggests that M.temminckii thermoregulate by altering its depth in the water column, because this species is rarely seen basking.

[23][24][25][21] In one study conducted in Louisiana, 79.8% of the stomach contents of adult alligator snapping turtles was found to be composed of other turtles, although the resistance of shell and reptile-bone fragments to digestion may have led these fragments to remain longer in the digestive tract than other items.

Between March and October, stomach samples of 65 turtles showed that 56% of their diet by volume was composed of acorns of water, overcup, and willow oaks.

By day, it may try to attract fish and other prey by sitting quietly at the bottom of murky water and letting its jaws hang open to reveal its tongue appendage, which looks like a small, pink worm in the back of its gray mouth, and lure the prey into striking distance.

[28] Small fish, such as minnows, are often caught in this way by younger alligator snapping turtles, whereas adults must eat a greater quantity per day and must forage more actively.

[32] Though its potential lifespan in the wild is unknown, the alligator snapping turtle is believed to be capable of living to 200 years of age, but 80 to 120 is more likely.

[5] Their largest predator in many parts of their range is the northern river otter (Lontra canadensis) when the turtles are young.

Due to its potential size and specific needs, it does not make a particularly good pet for any but the most experienced aquatic turtle keepers.

Due to the turtle's sheer size, handling an adult specimen poses significant problems.

A larger turtle, with its proportionately longer neck and greater reach, is held safely by grasping it just behind the head or close to the tail's base.

However, if provoked, it is quite capable of delivering a powerful bite which can easily amputate fingers or cause other significant injuries, such as cuts.

[36] In some U.S. states, where the alligator snapping turtle does not naturally occur (such as California), it is prohibited from being kept as a pet by residents.

Some alligator snapping turtles were released or escaped into waters of the Czech Republic, Germany and Hungary.

[41] Certain EU countries have strong laws against keeping the alligator snapping turtle without permission, as it is an invasive species.

It was captured and euthanized by the Oregon Department of Fish and Wildlife, which considers alligator snapping turtles to be an invasive species.

In June 2024, it was announced captive alligator snapping turtles, bred in Oklahoma, would be reintroduced to the Neosho River in Kansas in hopes of bringing them back to its waterways.