Description
The alligator snapping turtle is characterized by a large, heavy head, and a long, thick shell 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 yellowpatterns 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 183 kilograms (400 lb) Alligator Snapping Turtle found in Kansas in 1937, but the largest verifiable one is debatable. One weighed at the Shedd Aquarium in Chicago was a 16-year resident giant alligator snapper weighing 113 kilograms (250 lb), sent to the Tennessee State Aquarium as part of a breeding loan in 1999, where it subsequently died. Another was 107 kilograms (240 lb), and housed at the Brookfield Zoo in suburban Chicago. They generally do not grow quite that large. Breeding maturity is attained at around 16 kilograms (35 lb), when the length is around 38 centimetres (15 in), but then they continue to grow through life. Alligator snapping turtles generally range in carapace length from 40.4 to 80.8 centimetres (15.9 to 31.8 in) and weigh from 68 to 80 kilograms (150 to 180 lb). Males are typically larger than females. Among extant freshwater turtles, only the little-known giant softshell turtles of the genera Rafetus and Pelochelys, native to Asia, reach comparable sizes.
In mature specimens (carapace length over 30 centimetres (12 in)) male and female can be differentiated by the position of the cloaca from the carapace and the thickness of the tail's base. A mature male's cloaca extends beyond the carapace edge, a female's is placed exactly on the edge if not nearer to the plastron. The base of the tail of the male is also thicker as compared to females because of the hidden reproductive organs.
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.
Contrary to claims that alligator snapping turtles possess the second strongest bite force of any animal, it has been recorded at 158 ± 18 kilograms-force (1,550 ± 180 N; 350 ± 40 lbf) which is lower than several other species of turtle and at about the same level as humans. Still, these turtles must be handled with extreme care.
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