Daily Archives: October 10, 2016
iPhoneOgraphy – 10 Oct 2016 (Day 284/366)
The alligator snapping turtle (Macrochelys temminckii) is one of the heaviest freshwater turtles in the world,. It is often associated with, but not closely related to, the common snapping turtle, which is in the genus Chelydra. The specific epithet temminckii is in honor of Dutch zoologist Coenraad Jacob Temminck.
Although it was once believed to be only one species, a recent study suggests that it is actually three separate species; Macrochelys temminckii, Macrochelys suwanniensis, and Macrochelys apalachicolae.
The alligator snapping turtle is given its name because of its immensely powerful jaws and long, spring-like neck, as well as distinct ridges on its shell that are similar to the rough, ridged skin of an alligator.
The alligator snapping turtle is found primarily in southeastern United States waters. They are found from the Florida Panhandle west to East Texas, north to southeastern Kansas, Missouri, southeastern lowa, western Illinois, southern Wisconsin southern Indiana, western Kentucky, and western Tennessee. They are found on the Missouri River at least as far north as the Gavins Point Dam, the southernmost dam on the Missouri River at Yankton, South Dakota, and are featured in the Gavins Point Dam Aquarium. Typically, only nesting females venture onto open land.
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 yellow patterns around their eyes, serving to break up the outline of the eyes to keep the turtle camouflaged. Their eyes are also surrounded by a star-shaped arrangement of fleshy, filamentous “eyelashes”.
Though not verified, a 183 kg (403 lb) alligator snapping turtle was 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 kg (249 lb), sent to the Tennessee Aquarium as part of a breeding loan in 1999, where it subsequently died. Another weighing 107 kg (236 lb) was housed at the Brookfield Zoo in suburban Chicago. Another large turtle reportedly weighed 135 kg (298 lb). They generally do not grow quite that large. Breeding maturity is attained around 8 kg (18 lb), when the length is around 33 cm (13 in), but then they continue to grow through life. 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). Males are typically larger than females. 88 adult alligator snapping turtles averaged 21.05 kg (46.4 lb), 92 averaged 19.72 kg (43.5 lb), and 249 averaged 13.5 kg (30 lb). Usually very old males comprise the specimens that weigh in excess of 45 kg (99 lb) per most population studies. Among extant freshwater turtles, only the little-known giant softshell turtles of the genera Chitra, Rafetus, and Pelochelys, native to Asia, reach comparable sizes.
In “mature” specimens (carapace length over 30 cm (12 in)), males and females 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 one of the strongest bite forces of any animal, it has been recorded at 158 ± 18 kgf (1,550 ± 180 N; 348 ± 40 lbf), which is lower than several other species of turtles and at about the same level as humans, relative to the turtle’s body size. Still, these turtles must be handled with extreme care and considered potentially dangerous. This species can bite through the handle of a broom and rare cases have been reported where human fingers have been cleanly bitten off by the species. No human deaths have been reported to have been caused by alligator snapping turtles.
Maturity is reached around 12 years of age. Mating takes place yearly, in 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 about two months later. The gender of the young 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.
Though their potential lifespans in the wild are unknown, alligator snapping turtles are believed to be capable of living to 200 years of age, but 80 to 120 is more likely. In captivity, they typically live between 20 and 70 years.