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Common Snapping Turtle (Chelydra serpentina) - Wiki
| 제목: | Common Snapping Turtle (Chelydra serpentina) - Wiki
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Snapping turtle
From Wikipedia, the free encyclopedia
[Photo] Common Snapping Turtle (Chelydra serpentina). Date June 7, 2007. Author Smee (http://commons.wikimedia.org/wiki/User:Smee). The author released this image into the public domain.
The Snapping Turtle (Chelydra serpentina), or more formally referred to as Common Snapping Turtle when distinguishing them from their larger cousins (Macrochelys), and are popularly nicknamed "snappers". They are large freshwater turtles of the family Chelydridae, ranging from southeastern Canada west to the Rocky Mountains (and beyond, where introduced), and south through Mexico to Ecuador.
Common snappers are noted for their pugnacious dispositions when out of the water, their powerful beak-like jaws and their highly mobile head and neck (hence the specific name "serpentina," meaning "snake-like"). In some areas they are hunted heavily for their meat, a popular ingredient in turtle soup. Common snappers have lived for up to 39 years in captivity, while the lifespan of wild individuals is estimated to be around 30 years.
Anatomy and morphology
Chelydra serpentina have though these ridges tend to be more pronounced in younger individuals). The carapace (shell) length in adulthood may be nearly 50 cm (20 inches) (though 20-36 cm, or 8-14 inches, is more common), with C. serpentina and its subspecies commonly weighing up 4.5-16 kg (10-35 lb). Exceptional individuals may reach 34 kg (75 lb).
Ecology and life history
Common habitats are shallow ponds, shallow lakes, or streams. Some may inhabit brackish environments, such as estuaries. Common Snapping Turtles sometimes bask - though rarely observed - by floating on the surface with only their carapace exposed, though in the northern parts of their range they will also readily bask on fallen logs in early spring. In shallow waters, common snappers may lie beneath a muddy bottom with only the head exposed, stretching their long necks to the surface for an occasional breath (note that their nostrils are positioned on the very tip of the snout, effectively functioning as snorkels). Snapping turtles are omnivores, consuming both plant and animal matter, and are important aquatic scavengers; but they are also active hunters that prey on anything they can swallow, including many invertebrates, fish, frogs, reptiles (including snakes and smaller turtles), unwary birds and small mammals.
Snappers will also travel extensively overland to reach new habitat or to lay eggs. Pollution, habitat destruction, food scarcity, overcrowding and other factors will drive snappers to move overland; it is quite common to find them travelling far from the nearest water source. Snapping turtles mate from April through November, with their peak laying season in June and July. The female can hold sperm for several seasons, utilizing it as necessary. Females travel over land to find sandy soil in which to lay their eggs, often some distance from the water. After digging a hole, the female typically deposits 25 to 80 eggs each year, guiding them into the nest with her hind feet and covering them with sand for incubation and protection. Incubation time is temperature-dependent, ranging from 9 to 18 weeks. In cooler climates, hatchlings overwinter in the nest.
Systematics & taxonomy
Four subspecies of Chelydra serpentina are typically recognized. C. s. serpentina is the form present across the majority of its range, occurring east of the Continental Divide into most of the southern United States, and parts of northern Mexico. C. s. osceola occurs only in Florida up to the Okefenokee area of southern Georgia. C. s. acutirostris and C. s. rossignonii are neotropical, C. s. rossignonii occurring in southern Mexico, Belize, Guatemala and Honduras while C s. acutirostris ranges from Nicaragua across the Central American isthmus down the South American Pacific coastal region.
Evolutionary history
The genus Chelydra is exclusively North American. Its earliest occurrence is from the late Barstovian (middle Miocene) of Cherry County, Nebraska. This assignment is based on a single partial right hypoplastron that is described as being markedly more massive and rugose than C. serpentina. No species assignment was made for this specimen. Published reports of Chelydra from the Pliocene involve very scant material. A large, undescribed fossil member is known from upper Pliocene localities of northern Florida. Specimens of this new species are by far the largest Chelydra ever discovered, reaching a carapace length of over 127 cm (50 inches). Abundant records of Chelydra from the Pleistocene have been published.
Importance to humans
In captivity
It is a common misconception that a Snapping Turtle may be safely picked up by its tail, with no harm to the animal; in fact, this has a high chance of injuring the turtle, especially the tail itself and the vertebral column. A handler must also be wary of injury to themself. Snapping turtles are aptly named, as they can snap with amazing speed and power; a full grown snapper can easily bite off a finger or toe. The safest method, of course, is to avoid handling a snapper at all. If moving it is absolutely necessary, scooping and lifting the turtle just off the ground with a shovel (especially a snow shovel), if done quickly, may be safest and easiest for all concerned parties.
Lifting the turtle with the hands is difficult and dangerous. Some snappers can-and will-stretch their necks halfway back across their own carapace to bite. Manual lifting (which should be done only if no other options are available) is best accomplished by sliding fingers behind the turtle's hind legs, with the tail between the hands and gripping the turtle between the fingers and thumbs. The handler then proceeds to lift the turtle only just off the ground. The turtle will probably squirm and try to dislodge the handler's hands with its hind legs. Even a small snapper is relatively powerful for its size, with long sharp claws; further, due to their aquatic inclinations these turtles are often slimy and wet, and they are good at causing prospective handlers to lose their grip. In any case that a snapping turtle must be handled, it is best to have the turtle on the ground or very close. Wild turtles may be covered with a smelly pond slime and may also defecate, urinate, or musk on a handler.
When raised in captivity, a snapper may sometimes become docile and show preference for its keeper. It may show signs of recognizing individual people and will seek out those whose company it tolerates. Some can be taught to obey simple commands, but this can be a long process, as snapping turtles display the stubborn nature that is a defining characteristic of all turtle species. Common snappers kept as pets can become quite corpulent (up to 39 kg, or 86 lb); and even properly fed individuals may be difficult to move without their cooperation - and moving may become essential, as turtles require frequent water changes to remain content and healthy.
Popular history, myths and trivia
The Common Snapper, known commonly and in folklore as the "Ograbme," was the central feature of a famous American political cartoon published in 1808, in protest at the Jeffersonian Embargo Act of 1807. The cartoon depicted a Snapping Turtle, jaws locked fiercely to an American trader who was attempting to carry a barrel of goods onto a British ship. The trader was seen whimsically uttering the words "Oh! this cursed Ograbme" ("embargo" spelled backwards). This piece is widely considered a pioneering work within the genre of the modern political cartoon.
In 2006, the snapping turtle was declared the "state reptile" of New York.
http://en.wikipedia.org/wiki/Snapping_turtle
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