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American alligator

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Alligator mississippiensis
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Sauropsida
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 only native 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. Adult male alligators are typically 13 to 14.7 feet long (3.96 to 4.48 meters), while adult females average 9.8 feet (2.99 meters).[1][2] Male alligators may grow to 454.5 kg (1000 lb)[3] and females can grow to 72 kg (160 lbs). One American Alligator allegedly reached a length of 19 feet, 2 inches (5.8 meters),[4] 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, are generally slow-moving on land and can lunge short distances very quickly. They have five claws on each front foot and four on each rear foot. Discovery Channel's Animal Face Off team estimated a fully grown gator's bite force at 3000lbf and as part of a National Geographic Special, Greg Erickson of Florida State University, Kent Vliet of the University of Florida and Kristopher Lapping of Northern Arizona University provoked American alligators, at the St. Augustine Alligator Farm and Zoological Park in Florida, into biting a bar studded with piezoelectric sensors. The largest alligator they tested was able to exert a force of 9.45 kN (2,125 lbf).

Habitat

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.

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 7.2 degrees, an alligator can survive in such temperatures for some time without apparent discomfort [citation needed]. It is thought that this adaptiveness is the reason why American alligators spread farther north than the American crocodile.[5] In fact, the American alligator is the most northernly distributed of all crocodilians and the one most equipped to deal with cooler conditions.[6]

Gator holes

The alligator's greatest value to the marsh and the other animals that inhabit it are the "gator holes" that many adults create and expand on over a period of years. An alligator uses its mouth and claws to uproot vegetation to clear out a space; then, shoving with its body and slashing with its powerful tail, it wallows out a depression that stays full of water in the wet season and holds water after the rains stop. During the dry season, and particularly during extended droughts, gator holes provide vital water for fish, insects, crustaceans, snakes, turtles, birds, and other animals in addition to the alligator itself.

Sometimes, the alligator may expand its gator hole by digging beneath an overhanging bank to create a hidden den. After tunneling as far as 20 feet (6 m), it enlarges the den, making a chamber with a ceiling high enough above water level to permit breathing. This is not the alligator's nest but merely a way for the reptile to survive the dry season and winters.

Diet

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. Sub adult alligators take a larger variety of prey; ranging from a snake or turtle to a bird and moderate sized mammals like a raccoon.

Once an alligator reaches adulthood, any animal living in the water or coming to water to drink is potential prey. Adult alligators will eat a razorback, a 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.[7] The American alligator is known as King of the Everglades.[8]

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[9].

Reproduction

A juvenile American Alligator 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.

A young American alligator swimming.

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.[5] 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)[10] 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[citation needed].

Since 1948, there have been more than 275 unprovoked attacks on humans in Florida, of which at least 17 resulted in death[11]. 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 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[12]

Endangered species recovery

An albino alligator; this trait is more common 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 U.S. 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. Photo by Lori Oberhofer, National Park Service.

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[13][14] and sometimes lost (see adjacent image)[15] 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.[15]

See also

Notes

  1. ^ Crocodile Species - American Alligator
  2. ^ ADW: Alligator mississippiensis: Information
  3. ^ <http://www.eparks.org/marine_and_coastal/marine_wildlife/alligator.asp>
  4. ^ Everglades National Park article on the American Alligator
  5. ^ a b Guggisberg, C.A.W. (1972). Crocodiles: Their Natural History, Folklore, and Conservation. pp. pp.195. ISBN 0715352725. {{cite book}}: |pages= has extra text (help)
  6. ^ Alligator physiology and life history: the importance of temperature, Valentine A. Lance. Experimental Gerontology, Vol. 38, Issue 7, July 2003, pp. 801-805.
  7. ^ American Alligator
  8. ^ <http://www.biol.andrews.edu/everglades/organisms/Vertebrates/reptiles/alligators_crocs/gator2/alligator_index.html>
  9. ^ <http://www.sciencedaily.com/releases/2002/03/020328073615.htm>
  10. ^ Animal Planet :: Australia Zoo - American Alligator
  11. ^ http://myfwc.com/gators/faq/lwa.htm
  12. ^ http://archives.cnn.com/2000/CAREER/trends/12/11/gatorman/
  13. ^ Gator-guzzling python comes to messy end. Published 2005-10-05 by The Associated Press, last accessed 2008-03-11.
  14. ^ Butler, Rhett A. (2005-10-05 Python explodes after swallowing 6-foot alligator in Florida Everglades. Mongabay.com, last accessed 2008-03-11
  15. ^ a b U.S. 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, last accessed 2008-03-11.
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