alligator snapping turtle

Alligator Snapping Turtle
Conservation status
Vulnerable (IUCN 2.3)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Testudines
Family:	Chelydridae
Genus:	Macrochelys
Species:	M. temminckii
Binomial name
Macrochelys temminckii Troost, 1835
Synonyms
Macroclemmys temminckii Boulenger, 1889 Chelonura temminckii Troost, 1835 Testudo planitia Gmelin, 1789

The Alligator Snapping Turtle (Macrochelys temminckii) is one of the largest freshwater turtles in the world. It is a larger and less aggressive^{[citation needed]} relative of the Common Snapping Turtle. The epithet temminckii is in honor of Dutch zoologist Coenraad Jacob Temminck.^[1]

Distribution and habitat

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 three hours. Typically only nesting females will venture onto open land.

Surprisingly, due to the pet trade and other factors the species has found its way to Asia and Europe with a breeding/research center found in Japan.^[2]

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 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,^[3] but the largest one actually on record is debatable. One weighed at the The Shedd aquarium in Chicago was a 16-year resident giant alligator snapper weighing 249 lbs. sent to the Tennessee State Aquarium as part of a breeding loan in 1999. Another was 236 lbs, and housed at the Brookfield Zoo in suburban Chicago. Both of these may still be alive. Further research is required. 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.^[4] Alligator snapping turtles can also range in length from 16 to 32 inches (40.4 to 80.8 cm).^[5]

Head of a young Alligator Snapping Turtle

In mature specimens (carapace length over 12 inches) 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 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.

The Alligator Snapping Turtle possesses the second strongest bite strength of any animal in the world^{[citation needed]}, and can be quite aggressive when cornered. These turtles must be handled with extreme care.^[4]

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. In northern states such as Michigan young hatchlings will live off plants also, such as water lettuce and other floating grass, shrub, and flower-like organisms. They usually obtain this behavior when food is scarce or when it is early in the summer months. Fishermen have glorified the species' ability to catch fish and to 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 beef, chicken and pork although these are not always healthy on a day to day basis. Though not a primary food source for them, adult Alligator snappers have been known to kill and eat small alligators^[6] that have been confined with, such as in a net, small bog, or poorly-planned aquarium display.^{[citation needed]}

Reproduction and lifespan

Immature snapping turtle, about 4 inches (10 cm) across the shell

Maturity is reached at around 12 years of age.^[7] 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^[5] 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.^[8]

Though their potential lifespans in the wild are unknown, alligator snapping turtles are believed to be capable of living to 150 years of age. According to an episode of "Dirty Jobs" on the Discovery Channel, there are reports of living Alligator Snapping turtles with musket balls from the American Civil War lodged in them. In captivity, they typically live from anywhere between 20 to 70 years of age.^[9]

In captivity

Correct handling of a 45 lb Alligator Snapping Turtle at Austin Reptile Service, in Austin, Texas.

Alligator snapping turtles are often captive-bred as pets and are readily available in the exotic animal trade. Due to their potential size and specific needs, they do not make particularly good pets for any but the most experienced aquatic turtle keepers.^[10] Due to sheer size, handling adult specimens can pose significant problems. The turtle can be handled with relative safety by holding them at the sides of the carapace. A large individual can be held by grasping the turtle firmly in the anterior, just behind the head, and posterior portions of the carapace.

Despite their reputation, they are typically not prone to biting, but when antagonized are quite capable of delivering a bite with their powerful jaws which can cause significant harm to a human, easily amputating fingers.^[11] Some states where alligator snapping turtles do not naturally occur (such as California) prohibit them from being kept as pets by residents.

Conservation status

The alligator snapping turtle is primarily vulnerable to humans from habitat loss and hunting. Some are hunted for their carapaces; the plastron of the turtle is valued because of its shape as a cross. There are accounts of large (50+ lb) turtles being caught both purposely 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 and all international trade in this species.).^[12]

The alligator snapping turtle is now endangered in several states, including Illinois.

References

External links

• Alligator vs. Common Snapping Turtle - Chelydra.org
• CRUNCH, The Alligator Snapping Turtle

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