Jump to content

American alligator

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by A Raider Like Indiana (talk | contribs) at 21:12, 11 May 2009 (Reverted edits by 68.214.210.220 to last version by Postdlf). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Alligator mississippiensis
An American Alligator in captivity at the Columbus Zoo, in Powell, Ohio
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Reptilia
Order:
Crocodilia
Family:
Alligatoridae
Genus:
Alligator
Species:
A. mississippiensis
Binomial name
Alligator mississippiensis
(Daudin, 1801)
American Alligator range map

The American Alligator, Alligator mississippiensis, (known colloquially as simply gator) is one of the two living species of Alligator, a genus within the family Alligatoridae. The American Alligator is native only to the Southeastern United States, where it inhabits wetlands that frequently overlap with human-populated areas. It is larger than the other extant alligator species, the Chinese Alligator.

Anatomy

Forelimb showing the large claws and slight webbing between the toes.
Tail which is for aquatic propulsion and as a weapon of defense

The American Alligator has a large, slightly rounded body, with thick limbs, a broad head, and a very powerful tail. They generally have an olive, brown, gray or nearly black color with a creamy white underside. Algae-laden waters produce greener skin, while tannic acid from overhanging trees can produce often darker skin.[2] Adult male alligators are typically 11.2 to 14.7 ft (3.4 to 4.5 m) in length, while adult females average 8.2 to 9.8 ft (2.5 to 3.0 m).[3][4][5] One American Alligator allegedly reached a length of 19 feet, 2 inches (5.8 meters),[6] which would make it the largest recorded. The tail, which accounts for half of the alligator's total length, is primarily used for aquatic propulsion. The tail can also be used as a weapon of defense when an alligator feels threatened. Alligators travel very quickly in water and while they are generally slow-moving on land, alligators can lunge short distances very quickly. They have five claws on each front foot and four on each rear foot. American Alligators have the strongest bite of any living animal, measured at up to 9452 newtons in laboratory conditions.[7]
Some alligators are missing an inhibited gene for melanin, which makes them albino. These alligators are extremely rare and practically impossible to find in the wild. They could survive only in captivity. Like all albino animals, they are very vulnerable to the sun and predators.[8]

Habitat

American alligators are mostly found in the Southeastern United States, from Merchants Millpond State Park in North Carolina south to Everglades National Park in Florida and west to the southern tip of Texas. They are also found in the U.S. states of North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, Arkansas, Louisiana, Texas, and Oklahoma. Florida and Louisiana currently have the largest population of alligators. Florida has an estimated population of 1 to 1.5 million while Louisiana has an estimated poplulation of 1.5 to 2 million.

Although primarily freshwater animals, alligators will occasionally venture into brackish water.[9] Alligators live in wetlands and this is the vital habitat that holds the key to their continued long-term survival. Alligators depend on the wetlands, and in some ways the wetlands depend on them. As apex predators, they help control the population of rodents and other animals that might overtax the marshland vegetation.

American alligators are less susceptible to cold than American Crocodiles. Unlike the American Crocodile which would quickly succumb and drown in water of 45 degrees (7.2 C), an alligator can survive in such temperatures for some time without apparent discomfort.[10] It is thought that this adaptiveness is the reason why American alligators spread farther north than the American Crocodile.[10] In fact, the American alligator is found farther from the equator and is more equipped to deal with cooler conditions than any other crocodilian.[11]

Diet

Alligators are apex predators capable of killing large terrestrial prey. This large American alligator has caught an adult deer.

Alligators eat fish, birds, turtles, snakes, mammals, and amphibians. Hatchlings, however, are restricted to smaller prey items like invertebrates. Insects and larvae, snails, spiders, and worms make-up a big portion of a hatchling's diet. They will also eat small fish at any opportunity. As they grow, they gradually move onto larger fish, mollusks, frogs and small mammals like rats, and mice. Some adult alligators take a larger variety of prey ranging from a snake or turtle to a bird and moderate sized mammals like a raccoon or deer.

Once an alligator reaches adulthood, any animal living in the water or coming to the water to drink is potential prey. Adult alligators will eat razorbacks, deer, domestic animals including cattle and sheep, and are often known to kill and eat smaller alligators. In rare instances, large male alligators have been known to take down a Florida panther and an American Black Bear, making the American alligator the apex predator throughout its distribution.[12] The American alligator is known as King of the Everglades [13], although the American Crocodile (which shares parts of the Everglades with the Alligator) is capable of growing larger and has a far more powerful bite.

The stomachs of alligators often contain gastroliths. The function of these stones is to grind up food in the stomach and help with digestion. This is important because gators swallow their food whole. These gastroliths are also used in buoyancy control.

In 2002, the bite force on a 12 foot alligator was measured to be about 2100 pounds.[14]

Reproduction

Young American Alligator swimming, showing the distinctive yellow striping found on juveniles.

The breeding season begins in the spring. Although alligators have no vocal cords, males bellow loudly to attract mates and warn off other males during this time by sucking air into their lungs and blowing it out in intermittent, deep-toned roars.

Male alligators are also known to use infrasound during their mating behavior, as one of their routines is to engage in bellowing in infrasound while their head and tail is above the water, with their midsection very slightly submerged, making the surface of the water that is directly over their back literally "sprinkle" from their infrasound bellowing, in a so-called "water dance".[15]

Young American Alligators basking.

The female builds a nest of vegetation, sticks, leaves, and mud in a sheltered spot in or near the water. After she lays her 20 to 50 white, goose-egg-sized eggs, she covers them under more vegetation, which, like mulch, heats as it decays, helping to keep the eggs warm. This differs from Nile crocodiles who lay their eggs in pits.[10] The temperature at which alligator eggs develop determines their sex. Those eggs which are hatched in temperatures ranging from 90–93 °Fahrenheit (32.2–33.8 °C) turn out to be male, while those in temperatures from 82–86 °Fahrenheit (27.7–30 °C) end up being female. Intermediate temperature ranges have proven to yield a mix of both male and females. The female will remain near the nest throughout the 65-day incubation period, protecting the nest from intruders. When the young begin to hatch they emit a high-pitched croaking noise, and the female quickly digs them out.

The young, which are tiny replicas of adult alligators with a series of yellow bands around their bodies, then find their way to water. For several days they continue to live on yolk masses within their bellies. The baby spends about 5 months with the mother before leaving her.

Alligators reach breeding maturity at about 8 to 13 years of age, at which time they are about 6 to 7 feet (1.8–2.1 m) long. From then on, growth continues at a slower rate. The oldest males may grow to be 16 feet (4.85 m)[16] long and weigh up to 1,200 pounds (510 kg) during a lifespan of 30 or more years.

Alligators and humans

Alligators are capable of killing humans, but are generally wary enough not to see them as a potential prey. Alligator bites are serious injuries due to the risk of infection. Inadequate treatment or neglect of an alligator bite may result in an infection that necessitates amputation of a limb.[citation needed] The alligator's tail is a fearsome weapon capable of knocking a person down and breaking bones. Alligators are protective parents who will protect their young by attacking anything that comes too close or looks like it's aggressive and could kill one of the baby alligators.

Since 1948, there have been more than 275 unprovoked attacks on humans in Florida, of which at least 17 resulted in death.[17] There were only nine fatal attacks in the U.S. throughout the 70s, 80s, and 90s, but alligators killed 12 people from 2001 to 2007. In May 2006, alligators killed three Floridians in four days, two of them in the same day.[citation needed]

Several Florida tourist attractions have taken advantage of fears and myths about alligators — as well as the reality of their danger — through a practice known as alligator wrestling. Created in the early 20th Century by some members of the Seminole Tribe of Florida, this tourism tradition continues to the present day[18]

Endangered species recovery

An albino alligator could survive only in captivity.

Historically, alligators were depleted from many parts of their range as a result of market hunting and loss of habitat, and 30 years ago many people believed this unique reptile would never recover. In 1967, the alligator was listed as an endangered species (under a law that preceded the Endangered Species Act of 1973), meaning it was considered in danger of extinction throughout all or a significant portion of its range.

A combined effort by the United States Fish and Wildlife Service, state wildlife agencies in the South, and the creation of large, commercial alligator farms saved these unique animals. The Endangered Species Act outlawed alligator hunting, allowing the species to rebound in numbers in many areas where it had been depleted. As the alligator began to make a comeback, states established alligator population monitoring programs and used this information to ensure alligator numbers continued to increase. In 1987, the Fish and Wildlife Service pronounced the American alligator fully recovered and consequently removed the animal from the list of endangered species. The Fish and Wildlife Service still regulates the legal trade in alligator skins and products made from them.

Although the American alligator is secure, some related animals — such as several species of crocodiles and caimans — are still in trouble.

Dangers in Florida

An American alligator and a Burmese Python locked in struggle

In Florida, alligators face ambient temperature patterns unlike elsewhere in their range. The consistently high temperatures lead to increased metabolic cost.

Alligators in the Everglades have reduced length to weight ratio, reduced total length, and delayed onset of sexual maturity compared with other parts of their range. The reason for this poor condition is currently suspected to be a combination of low food availability and sustained high temperatures.

Additionally, the Everglades National Park has confirmed in 2003 that there is a significant population of Burmese Pythons in Florida. These non-native snakes have sometimes won[19][20] and sometimes lost (see adjacent image)[21] in battles with alligators, but the introduction of a potential predator could have a devastating impact on an endangered species as many have been found in the stomachs of these invaders.[21]

Farming

Main article: Alligator farm

Alligator farming is a big and growing industry in Georgia, Florida, Texas and Louisiana. These states produce a combined annual total of some 45,000 alligator hides. Alligator hides bring good prices and hides in the 6 to 7 feet (1.8 to 2.1 m) range have sold for $300 each, though the price can fluctuate considerably from year to year. The market for alligator meat is growing and approximately 300,000 pounds (140,000 kg) of meat is produced annually. According to the Florida Department of Agriculture and Consumer Services, raw alligator meat contains roughly 200 calories per 3 ounces (85 g) serving size, of which 27 calories come from fat.[22]

Alligator meat is sometimes used in jambalayas, soups, and stew.

See also

Notes

  1. ^ Template:IUCN2008
  2. ^ "Alligators at Animal Corner". Retrieved 2009-02-04.
  3. ^ "Crocodilian Species — American Alligator (Alligator mississippiensis)". Flmnh.ufl.edu. Retrieved 2008-10-14.
  4. ^ Woodward, Allan R.; White, John H.; Linda, Stephen B. (1995). "Maximum Size of the Alligator (Alligator mississippiensis)". Journal of Herpetology. 29 (4): 507-513.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  5. ^ http://nationalzoo.si.edu/Animals/ReptilesAmphibians/Facts/FactSheets/Americanalligator.cfm
  6. ^ "Salt Grass Flats — American Alligator". Saltgrassflats.com. Retrieved 2008-12-02.
  7. ^ "The ontogeny of bite-force performance in American alligator (Alligator mississippiensis)" (PDF). Journal of Zoology. 260 (3): 317–327.
  8. ^ "White albino alligators". .softpedia.com. Retrieved 2008-10-27.
  9. ^ "American Alligator". Uga.edu. Retrieved 2008-12-02.
  10. ^ a b c Guggisberg, C.A.W. (1972). Crocodiles: Their Natural History, Folklore, and Conservation. p. 195. ISBN 0715352725.
  11. ^ Alligator physiology and life history: the importance of temperature, Valentine A. Lance. Experimental Gerontology, Vol. 38, Issue 7, July 2003, pp. 801-805.
  12. ^ "American Alligator". Sciencedaily.com. Retrieved 2008-10-14.
  13. ^ "Alligator Page 2". Biol.andrews.edu. Retrieved 2008-10-14.
  14. ^ "Alligator's Bite Could Lift A Small Truck". Sciencedaily.com. ScienceDaily (Mar. 29, 2002). Retrieved 2008-10-14. {{cite web}}: Check date values in: |date= (help)
  15. ^ February 11, 2008 (2008-02-11). "Gator Water Dance". YouTube. Retrieved 2009-03-03.{{cite web}}: CS1 maint: numeric names: authors list (link)
  16. ^ "Animal Planet :: Australia Zoo — American Alligator". Animal.discovery.com. October 13, 2008. Retrieved 2008-10-14.
  17. ^ "Living with Alligators". Myfwc.com. Retrieved 2008-10-14.
  18. ^ Larry Keller CNN.com/career Senior Writer (December 11, 2000). "CNN.com — Career — Alligator wrestler: Briefcase with teeth — December 11, 2000". Archives.cnn.com. Retrieved 2008-10-14. {{cite web}}: |author= has generic name (help)
  19. ^ Gator-guzzling python comes to messy end. Published 2005-10-05 by Associated Press. Retrieved 2008-03-11.
  20. ^ Butler, Rhett A. (2005-10-05 Python explodes after swallowing 6-foot alligator in Florida Everglades. Mongabay.com. Retrieved 2008-03-11.
  21. ^ a b United States Department of the Interior, U.S. Geological Survey (2008-02-20). USGS Maps Show Potential Non-Native Python Habitat Along Three U.S. Coasts. www.usgs.gov. Retrieved 2008-03-11.
  22. ^ "Calories in Alligator, Crocodile". Annecollins.com. Retrieved 2008-12-11.

External links

Wikimedia Commons has media related to Alligator mississippiensis.


Retrieved from "https://en.wikipedia.org/w/index.php?title=American_alligator&oldid=289328593"