The alligator snapping turtle (Macrochelys temminckii) is a related species to the common snapping turtle. The alligator snapping turtle, however, is considered the largest freshwater turtle in the world. It can live for over 150 years and can grow over 220 pounds!
Alligator snapping turtles live in the south eastern United States. They are found as far north as Chicago and as far west as Texas (map originally from National Geographic).
The alligator snapping turtle females lay only one batch of eggs per year. Males never leave the water, while females crawl out of the water to lay from 25 to 30 eggs. They dig a small hole and place them within. From the time of laying, it takes from 11 to 16 weeks for eggs to mature and hatch.
Unlike humans, turtles (as well as other related reptiles) determine the sex of their species by the temperature of the eggs during incubation. Females are produced when the egg temperature is higher than a certain mean temperature. Males are produced when the egg temperature is lower than this mean temperature. An easy way to remember this is, "hot chicks, cool dudes". However, snapping turtles are different. According to David Madge, D.Sc., snapping turtles produce females at high and low temperature extremes, while males are produced an intermediate temperatures.
When young alligator snapping turtles hatch, they are 2-3 inches long and already look just like the adults. From the time of hatching, it takes11 to 13 years before a turtle becomes reproductively mature and can start the life cycle again.
On average, an alligator snapping turtle will only live for about 60 years. However, there have been reports of snapping turtles with bullets from the civil war in their carapace. This indicates that they can live for up to 150 years.
These turtles eat almost anything they can get a hold of. Their primary diet consists of fish and invertebrates. Alligator snapping turtles are sit-and-wait ambush predators. Typically they lay on the mud at the bottom of a lake or stream. To attract their prey they expose a small worm-like tongue that wiggles. This attracts small prey. When the small prey approaches, the jaws snap shut.