The Alligator Snapping Turtle (Macrochelys temminckii) is one of the largest freshwater turtles in the world. It is a larger and slightly less aggressive relative of the Common Snapping Turtle. The epithet temminckii is in honor of Dutch zoologist Coenraad Jacob Temminck.[1] Distribution and habitat The Alligator Snapping Turtle is found in the Mississippi River and its tributaries throughout the Southeastern U.S.. They are also found in the Missouri River at least as far north as the Gavins Point Dam at Yankton, South Dakota. The Alligator Snapping Turtle has also been found in New England. It is also present in Indiana on the state's endangered species list. The largest freshwater turtle in North America, the alligator snapper keeps to primarily southern U.S. waters, while the smaller, more aggressive common snapper inhabits lakes and streams from South America to Canada. These turtles can remain submerged for up to an hour. Typically only nesting females will venture onto open land. Description The Alligator Snapping Turtle is characterized by a large, heavy head and a long, thick tail with three dorsal ridges of large scales (osteoderms) giving it a primitive appearance reminiscent of some of the plated dinosaurs. They can be immediately distinguished from the Common Snapping Turtle by the three distinct rows of spikes and raised plates on the carapace, whereas the Common Snapping Turtle has a smoother carapace. They are a solid gray, brown, black, or olive-green in color, and often covered with algae. They have radiating yellow patterns around the eyes, serving to break up the outline of the eye and keep the turtle camouflaged. Their eyes are also surrounded by a star-shaped arrangement of fleshy filamentous "eyelashes." There is an unverified report of a 403-pound Alligator Snapping Turtle found in the Neosho River in Kansas in 1937,[2] but the largest one actually on record is 236 lb, and housed at Brookfield Zoo in Chicago, Illinois. They generally do not grow quite that large. Average adult size is around 26 inches shell length with a weight of 175 lb. Males are typically larger than females.[3] Alligator snapping turtles can also range in length from 16 to 32 inches (40.4 to 80.8 cm). [4] The inside of the turtle's mouth is camouflaged, and it possesses a vermiform (literally, "worm-shaped") appendage on the tip of its tongue used to lure fish, a form of Peckhamian mimicry. The turtle hunts by lying motionless in the water with its mouth wide open. The vermiform tongue imitates the movements of a worm, luring prey to the turtle's mouth. The mouth is then closed with tremendous speed and force, completing the ambush. The Alligator Snapping Turtle possesses extraordinary bite strength, and can be quite aggressive when cornered. These turtles must be handled with extreme care.[5] Fossil history Unlike the family Chelydridae as a whole, the genus Macroclemys is exclusively North American and is generally considered to contain three valid species: the extant M. temminckii and the extinct M. schmidti and M. auffenbergi (described from the early middle Miocene of Nebraska and the middle Pliocene of Florida, respectively). Diet Alligator snappers are opportunistic carnivores more often at a young age, but are also scavengers. As they mature they become omnivores and do not pose a threat to fish populations. Fishermen have glorified the species' ability to catch fish and deplete fish populations. Minnows are usually the main source of meat for the species at a young age. They will eat almost anything they can catch. Their natural diet consists primarily of fish and dead fish carcasses (usually thrown overboard by fishermen), invertebrates, carrion, and amphibians, but they are also known to eat snakes, and even other turtles. In captivity they may consume almost any kind of meat provided, including rodents, beef, chicken and pork although these are not always healthy on a day to day basis. Though not a primary food source for them, Alligator snappers have been known to kill actual alligators they have been confined with, such as in a net, small bog, or poorly-planned aquarium display. Reproduction and lifespan Maturity is reached at around 12 years of age.[6] Mating takes place yearly; early spring in the southern part of their total range, and later spring in the north. The female builds a nest and lays a clutch of 10-50 eggs[4] about 2 months later. The sex of the baby alligator snapping turtles depends on the temperature at which the eggs are incubated. Nests are typically excavated at least 50 yards from the water's edge to prevent them from being flooded and drowned. Incubation takes from 100 to 140 days, and hatchlings emerge in the early fall.[7] Though their potential lifespans in the wild are unknown, alligator snapping turtles are believed to be capable of living to 150 years of age. In captivity, they typically live from anywhere between 20 to 70 years of age.[8] In captivity Conservation status The alligator snapping turtle is primarily vulnerable to humans from habitat loss and hunting. Some are also hunted for their carapaces; the plastron of the turtle is valued by some because of its shape as a cross. There are accounts of large (50+ lb) turtles being caught both purposefully and accidentally on recreational fishing lines called "trot lines." Abandoned trot lines are thought to be even more dangerous to turtles. Soup made from snapping turtle meat is considered by some to be a delicacy. This turtle is protected from collection throughout much of its range. The IUCN lists it as a threatened species, and as of June 14, 2006 it was afforded some international protection by being listed as a CITES III species (which will put limits on exportation from the United States).[10] The alligator snapping turtle is now endangered in several states, including Illinois. References
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