(Daudin, 1802 [originally Crocodilus])
|American Alligator range map|
The American alligator (Alligator mississippiensis), sometimes referred to colloquially as a gator or common alligator, is a large crocodilian reptile endemic to the Gulf and far south Atlantic states (southern North Carolina southward). It is one of two living species in the genus Alligator within the family Alligatoridae and larger than the other extant alligator species, the Chinese alligator. The American alligator is one of the second largest species in the family, Alligatoridae, only second to the black caiman. It is a species in which the males measure 3.4 m (11 ft) to 4.6 m (15 ft) in length, and can weigh 453 kg (1,000 lb). Females are smaller, measuring around 3 m (9.8 ft). The American alligator inhabits freshwater wetlands, such as marshes and cypress swamps from Texas to North Carolina. It is distinguished from the sympatric American crocodile by its broader snout, with overlapping jaws and darker coloration, and is less tolerant of seawater but more tolerant of cooler climates than the American crocodile which is found only in tropical climates.
Alligators are apex predators and consume fish, amphibians, reptiles, birds and mammals. Hatchlings feed mostly on invertebrates. Alligators also play important roles in wetland ecosystems through the creation of "alligator holes" which provide wetter or drier habitats for other organisms. During the breeding season, males bellow and use infrasound to attract females. Eggs are laid in a nest of vegetation, sticks, leaves, and mud in a sheltered spot in or near the water. Young are born with yellow bands around their bodies and are protected by their mother.
The American alligator is listed as Least Concern by the International Union for Conservation of Nature. Historially, hunting has decimated their population and the American alligator was listed as an endangered species by the Endangered Species Act of 1973. Subsequent conservation efforts have allowed their numbers to increase and the species was removed from the list in 1987. Alligators are now harvested for their skins and meat. The species is the official state reptile of three states: Florida, Louisiana and Mississippi.
Taxonomy and phylogeny 
The American alligator was first classified by French zoologist François Marie Daudin as Crocodilus mississipiensis in 1801. Georges Cuvier classified the genus Alligator in 1807. The American alligator shares this genus with the Chinese alligator. They are grouped in the family Alligatoridae with the caimans. The superfamily Alligatoroidea includes all crocodilians (fossil and extant) that are more closely related to the American alligator than to either the Nile crocodile or the gharial. Members of this superfamily first arose in the Late Cretaceous. Leidyosuchus of Alberta is the earliest known genus. Fossil alligatoriods have been found throughout Eurasia as land bridges across both the North Atlantic and the Bering Strait have connected North America to Eurasia during the Cretaceous, Paleogene and Neogene periods. Alligators and caimans split in North America during the late Cretaceous and the latter reached South America by the Paleogene, before the closure of the Isthmus of Panama during the Neogene period. The Chinese alligator likely descended from a linage that crossed the Bering land bridge, also during the Neogene. The modern American alligator is well represented in the fossil record of the Pleistocene.
Wild alligators range from long and slender to short and robust, possibly due to variations in factors like growth rate, diet and climate. Alligators have broad snouts, especially in captive individuals. When the jaws are closed, the edge of the upper jaws covers the lower teeth which fit into the jaws' depressions. Like the spectacled caiman, this species has a bony nasal ridge, though it is less prominent. The teeth number from 74–84. Dorsally, adult alligators may be olive, brown, gray or black in color while their undersides are cream colored.
Some alligators are missing an inhibited gene for melanin, which makes them albino. These alligators are extremely rare and almost impossible to find in the wild. They could survive only in captivity as they are very vulnerable to the sun and predators.
The American alligator is a fairly large species of crocodilian, with males reaching an average maximum size of 4.6 m (15 ft) in length, weighing up to 453 kg (1,000 lb), while females grow to a maximum of 3 m (9.8 ft). Occasionally, a large, old male may measure longer. There have been reports during the 19th and 20th centuries of larger males reaching 5 to 6 m (16 to 20 ft). The largest reported size was a male killed in 1890 on Marsh Island, Louisiana and reportedly measured at 5.8 m (19 ft) in length but no voucher specimen was available since the alligator was left on a muddy bank after having been taped due to having been too massive to relocate. If the size of this animal was correct, it would have weighed around 1,000 kg (2,200 lb). The largest alligator shot in Florida was 5.31 m (17.4 ft), as reported by the Everglades National Park. However on average, American alligators do not reach such extreme sizes. In males, size averages at around 3.4 to 4 m (11 to 13 ft) in length, weighing slightly in excess of 227 kg (500 lb), while in smaller females, it averages 2.7 m (8.9 ft), weighing slightly in excess of 91 kg (200 lb). Weight varies depending on length, age, health, season and available food sources. Similar to other reptiles, American alligators from the northern end of their range, such as southern Arkansas, Alabama, and northern North Carolina, tend to grow to smaller sizes. The largest alligator caught in Alabama was only 3.86 m (12.7 ft) in length, weighing 306.2 kg (675 lb).
When on land, the alligator moves either by sprawling or walking, the latter involving the reptile lifting its belly off the ground. The sprawling of alligators and other crocodilians is not identical to the sprawling of salamanders and lizards, being similar to walking. Thus the two forms of territorial locomotion can be term the "low walk" and the "high walk". Unlike most another land vertebrates, alligators increase their speed through the distal rather than proximal ends of their limbs. In the water, alligators swim like fish; moving their pelvic regions and tails from side to side. American alligators held the record as having the strongest laboratory-measured bite of any living animal, measured at up to 9,452 newtons (2,125 lbf) in laboratory conditions. It should be noted that this experiment had not at the time of the paper published been replicated in any other crocodilians and the same laboratory was able to measure a greater bite force in saltwater crocodiles. During respiration, airflow is unidirectional; looping through the lungs during inhalation and exhalation.
Distribution and habitat 
American alligators are only found in the Southeastern United States, from Great Dismal Swamp in North Carolina, south to Everglades National Park in Florida and west to the southern tip of Texas. They are found in the U.S. states of North Carolina, South Carolina, Georgia, Florida, Louisiana, Alabama, Mississippi, Arkansas, Texas, and Oklahoma. Alligators inhabit swamps, streams, rivers, ponds and lakes. Females and juveniles are also found in Carolina Bays and other seasonal wetlands. While they prefer freshwater, alligators sometimes enter more brackish water. However they are less tolerant of saltwater than crocodiles as the salt glands on their tongues are non-functioning. One study of alligators in north-central Florida found that males preferred open lake water during the spring while females used both swampy and open water areas. During summer, males still preferred open water while females stuck to the swamps to construct their nests and lay their eggs. Both sexes may den underneath banks or clumps of trees during the winter.
American alligators are less vulnerable to cold than American crocodiles. Unlike the crocodile, which would immediately succumb to the cold and drown in water of 45 °F (7.2 °C), an alligator can survive in such temperatures for some time without any signs of discomfort. It is thought that this adaptiveness is the reason why American alligators spread farther north than the American crocodile. In fact, the American alligator is found farther from the equator and is more equipped to deal with cooler conditions than any other crocodilian. When the water begins to freeze, alligators stick their snouts though the surface which allows them to breathe above the ice.
Ecology and behavior 
Alligators modify some wetland habitat, in flat areas such as the Everglades, by constructing small ponds known as "alligator holes". These create wetter or drier habitats for other organisms, such as plants, fish, invertebrates, amphibians, reptiles and mammals. In the limestone depressions of cypress swamps, alligator holes tend to be large and deep while those in marl prairies and rocky glades are usually small and shallow and those in peat depressions of ridge and slough wetlands are more variable. Man-made holes do not appear to have as large an effect. Alligators also may control the long term vegetation dynamics in wetlands by reducing the population of small mammals, particularly nutria, which may otherwise over-graze marsh vegetation. In this way, they provide a vital ecological service that may be important in reducing rates of coastal wetland losses in Louisiana.
Hunting and diet 
The American alligator is considered the apex predator throughout its range. They are opportunists and their diet is determined largely by both the size and age of the predating alligator and the size and availability of prey. Most alligators will eat a wide variety of animals, including invertebrates, fish, birds, turtles, snakes, amphibians and mammals, in their life cycle. Hatchlings mostly feed on invertebrates such as insects, larvae, snails, spiders, and worms. As they grow, alligators gradually move on to larger prey. Once an alligator reaches adulthood, any animal living in the water or coming to the water to drink is potential prey, due to the size and power of the alligator. However, most animals captured by alligators are considerable smaller than the alligator itself. Stomach contents show that, amongst native mammals, muskrats and raccoons are some of the most commonly eaten species. In Louisiana, where introduced nutria (a large aquatic rodent) are common, they are perhaps the most regular prey for adult alligators, although it is only larger adults alligators that commonly eat this species.
Other animals may occasionally be eaten, even large deer or feral wild boars, but these are not normally part of the diet. Occasionally, domestic animals, including dogs and calves, are taken as available but are secondary to wild and feral prey. Water birds, such as herons and egrets, storks and waterfowl, are taken when possible. Occasionally, unwary adult birds are grabbed and eaten by alligators, but most predation on bird occurs on unsteady fledgling birds in late summer as they attempt to make their first flights near the water's edge. Other prey, including snakes, lizards and various invertebrates are eaten occasionally by adults.
Fish and other aquatic prey taken in the water or at the water edge form the major part of alligator's diet and may be eaten at any time of the day or night. Adult alligators also spend considerable time hunting on land, up to 50 m (170 feet) from water, ambushing terrestrial animals on trailsides and road shoulders. Usually, terrestrial hunting occurs on nights with warm temperatures. When hunting terrestrial prey, alligators may also ambush them from the edge of the water by grabbing them and pulling the prey into the water, the preferred method of predation of larger crocodiles. The teeth of the alligator are designed to grip prey but can not rip or chew flesh like dentition of some other predators (such as canids and felids). The alligator is capable of biting though a turtle's shell or a moderately sized mammal bone.
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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. One of their routines is to engage in bellowing at this frequency while their head and tail are above the water. With their midsection very slightly submerged, they cause the surface of the water that is directly over and to either side of their back to literally "sprinkle" from their infrasound bellowing, in a so-called "water dance". Recently it was discovered that on spring nights alligators gather in large numbers for group courtship, the so-called "alligator dances".
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 eggs, about the size of a goose egg, she covers them with more vegetation, which heats as it decays, helping to keep the eggs warm. This differs from Nile crocodiles which lay their eggs in pits.
The temperature at which alligator eggs develop determines their sex (see temperature-dependent sex determination). Those eggs which are hatched at a temperature of 34 °C (93 °F) or more become males, while those at a temperature of 30 °C (86 °F) or lower become female. The nests built on levees are warmer and thus produce males while the cooler nests of wet marsh produce females. The female will remain near the nest throughout the 65-day incubation period, protecting it from intruders. When the young begin to hatch the mother quickly digs them out and carries them to the water in her mouth.
The young are tiny replicas of adult alligators with a series of yellow bands around their bodies that serve as camouflage. Hatchlings gather into pods and are guarded by their mother and keep in contact with her through vocalizations. High-pitched "yelping" distress calls (a trait common to many crocodilian species' hatchling young) signal danger and the mother will rush to their aid, and can rarely even be heard from hatchlings a short time before they break free from their eggs. Hisses signal aggression and non-distressed grunts keep each hatchling in contact with each other. Young alligators eat small fish, frogs, crayfish and insects. They are themselves preyed on by large fish, birds, raccoons and adult alligators. Mother alligators eventually become more aggressive towards their young, which encourages them to disperse. Young alligators grow 3–8 in (7.6–20 cm) a year and reach adulthood at 6 ft (1.8 m). An alligator can live up to 30 to 50 years.
Interactions with exotic species 
Nutria were introduced into coastal marshes from South America in the mid-1900s, and since then their population has exploded into the millions. They cause serious damage to coastal marshes and may dig burrows in levees. Hence, Louisiana has had a bounty to try to reduce nutria numbers. Large alligators, however, feed heavily on nutria, and thus alligators may not only control nutria populations in Louisiana, but prevent them spreading east into the Everglades. Since hunting and trapping preferentially take the large alligators that are the most important in eating nutria, some changes in harvesting may be needed to capitalize on the ability of alligators to control nutria.
Recently, a population of non-native Burmese Pythons has become established in Everglades National Park. While there have been observed events of predation by Burmese pythons on alligators and vice versa, there is currently no evidence of a net negative effect on alligator populations.
Conservation status 
Historically, hunting and habitat loss has decimated alligator populations throughout their range, and it was doubted as to whether the species would survive. In 1967, the alligator was listed as an endangered species (under a law that was the precursor Endangered Species Act of 1973), since it was believed to be in danger of extinction throughout all or a significant portion of its range.
Both the United States Fish and Wildlife Service (USFWS) and state wildlife agencies in the South contributed to the American alligator's recovery. Protection under the Endangered Species Act allowed the species to recuperate in many areas where it had been depleted. States begin monitoring their alligator populations to ensure that they would continue to grow. In 1987, the Fish and Wildlife Service removed the animal from the endangered species list as it was considered to be fully recovered. The Fish and Wildlife Service still regulates the legal trade in alligators and their products to protect still endangered crocodilians that may be passed off as alligators during trafficking.
Relationships with humans 
Attacks on humans 
Alligators are capable of killing humans, but are generally wary enough not to see them as a potential prey. Mistaken identity leading to an attack is always possible, especially in or near cloudy waters. Alligators are often less aggressive towards humans than large crocodile species, a few of which (mainly the Nile and Saltwater Crocodiles) may prey on humans with some regularity. Alligator bites are serious injuries due to the reptile's sheer bite force and risk of infection. Even with medical treatment, an alligator bite may still result in a fatal infection.
As human populations increase, and as they build houses in low lying areas, or hunt and fish near water, there are inevitably incidents where alligators threaten, or at least appear to threaten, human life. Humans tend to exaggerate causes of death that seem unusual. Hence, alligators receive undue attention relative to other far more common causes of death such as drowning or car accidents. Since 1948, there have been 275 documented attacks on humans in Florida (that is, about five incidents per year), of which at least 17 resulted in death. There were only nine fatal attacks in the US throughout the 1970s, '80s, and '90s, but alligators killed 12 people between 2001 and 2007. In May 2006, alligators killed three Floridians in less than a week.
Alligator wrestling 
Since the late 1880's, Alligator wrestling has been a source of great entertainment for residents of the northern USA (and elsewhere) when visiting the hot subtropical climates of the Gulf Coast and southeast States. Created by the Miccosukee and Seminole tribes prior to the arrival of Europeans, this tourism tradition continues to the present day despite criticism from animal rights activists.
Alligator farming 
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. 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 (840 kJ) per 3 ounces (85 g) serving size, of which 27 calories (130 kJ) come from fat.
The American alligator is the official state reptile of three states: Florida, Louisiana and Mississippi. In addition, Gators has been the nickname of the University of Florida's sports teams since 1911. In that year, a printer made a spur-of-the-moment decision to print an alligator emblem on a shipment of the school's football pennants; the mascot stuck, perhaps because the team captain's nickname was Gator.
See also 
- Alligator (film), a movie about a giant alligator living in the sewer of an Illinois town
- Wally Gator, a cartoon about an anthropomorphic alligator
- The Alligator People
- Brazos Bend State Park
- Swamp People (TV series)
- Sewer alligator
- Crocodile Specialist Group (1996). Alligator mississippiensis. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 24 February 2009.
- "Alligator mississippiensis: Species Description". Western Connecticut State University. Retrieved August 14, 2012.
- Brochu, Christopher A. (2003). "Phylogenetic approaches toward crocodylian history". Annual Review of Earth and Planetary Sciences 31: 357– 97. doi:10.1146/annurev.earth.31.100901.141308.
- Brochu, Christopher A. (1999). "Phylogenetics, Taxonomy, and Historical Biogeography of Alligatoroidea". Society of Vertebrate Paleontology Memoir 6: 9–100. doi:10.2307/3889340. JSTOR 3889340.
- "Crocodilian Species—American Alligator (Alligator mississippiensis)". Flmnh.ufl.edu. Retrieved 2008-10-14.
- "American Alligator: Species Profile". US National Parks Service. Retrieved August 14, 2012.
- "Zoo keeps albino alligator in the dark". NBC News.com. May 11, 2007. Retrieved August 15, 2012.
- . Animals.nationalgeographic.com
- . Philadelphia Zoo. Retrieved on 2013-04-13.
- Crocodiles and Alligators edited by S Charles A. Ross & Stephen Garnett. Checkmark Books (1989), ISBN 978-0816021741.
- Wood, Gerald (1983). The Guinness Book of Animal Facts and Feats. ISBN 978-0-85112-235-9.
- . Everglades.national-park.com
- . FloridaAdventuring.com
- "Gator factsheet". Savannah River Ecology Laboratory. Retrieved August 14, 2012.
- Reilly, S. M.; Elias, J. A. (1998). "Locomotion in alligator mississippiensis: kinematic effects of speed and posture and their relevance to the sprawling-to-erect paradigm". The Journal of Experimental Biology 201 (18): 2559–74. PMID 9716509.
- Fish, F. E. (1984). "Kinematics of undulatory swimming in the American alligator". Copeia 1984 (4): 839–43. doi:10.2307/1445326.
- Erickson, Gregory M.; Lappin, A. Kristopher; Vliet, Kent A. (2003). "The ontogeny of bite-force performance in American alligator (Alligator mississippiensis)" (PDF). Journal of Zoology 260 (3): 317–327. doi:10.1017/S0952836903003819.
- Farmer, C. G.; and Sanders, K. (2010). "Unidirectional airflow in the lungs of alligators". Science 327 (5963): 338–340. doi:10.1126/science.1180219. PMID 20075253.
- "American Alligator (Alligator mississippiensis)". Savannah River Ecology Laboratory. Retrieved August 16, 2012.
- "What's the difference between a crocodile and an alligator?". Flmnh.ufl.edu. Retrieved August 26, 2012.
- Goodwin, Thomas M. (1979). "Seasonal activity ranges and habitat preferences of adult alligators in a north-central Florida lake". Journal of Hepatology 13 (2): 157–64. JSTOR 1563922.
- Guggisberg, C.A.W. (1972). Crocodiles: Their Natural History, Folklore, and Conservation. Newton Abbot: David & Charles. p. 195. ISBN 0-7153-5272-5.
- Lance, Valentine A. (2003). "Alligator physiology and life history: the importance of temperature". Experimental Gerontology 38 (7): 801–805. doi:10.1016/S0531-5565(03)00112-8. PMID 12855291.
- Campell, Mark R.; Mazzotti, Frank J. (2004). "Characterization of Natural and Artificial Alligator Holes". Southeastern Naturalist 3 (4): 583–94. doi:10.1656/1528-7092(2004)003[0583:CONAAA]2.0.CO;2.
- Keddy, P.A., L. Gough, J.A. Nyman, T. McFalls, J. Carter and J. Siegrist (2009). Alligator hunters, pelt traders, and runaway consumption of Gulf coast marshes: A trophic cascade perspective on coastal wetland losses. pp. 115–133 in B.R. Silliman, E.D. Grosholz, and M.D. Bertness (eds.) Human Impacts on Salt Marshes. A Global Perspective. University of California Press, Berkeley, CA ISBN 0520258924 Google Books
- Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK ISBN 0521783674.
- Dinets, V.L. (2011). "On terrestrial hunting in crocodilians". Herpetological Bulletin 114: 15–18.
- WEC203/UW230: Living with Alligators: A Florida Reality. Edis.ifas.ufl.edu. Retrieved on 2012-08-21.
- Garrick, L.D. and Lang, J.W. (1977). "Social Displays of the American Alligator". American Zoologist 17: 225–239.
- Dinets, V.L. (2010). "Nocturnal behavior of the American Alligator (Alligator mississippiensis) in the wild during the mating season". Herpetological Bulletin 111: 4–11.
- Joanen, T.; Ferguson, M. W. J. (1982). "Temperature of egg incubation determines sex in Alligator mississippiensis". Nature 296 (5860): 850–53. doi:10.1038/296850a0. PMID 7070524.
- Hunt, R. H; Watanabe, M. E. (1982). "Observations on the maternal behavior of the American alligator, Alligator mississippiensis". Journal of Herpetology 16 (3): 235–39. JSTOR 1563716.
- Gator-guzzling python comes to messy end. Associated Press (2005-10-05). Retrieved 2008-03-11.
- Butler, Rhett A. (2005-10-05) Python explodes after swallowing 6-foot alligator in Florida Everglades. Mongabay.com. Retrieved 2008-03-11.
- 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.
- "American Alligator Alligator mississippiensis". U.S. Fish and Wildlife Service. February, 2008. Retrieved September 3, 2012.
- Crocodile and Alligator Differences – Animal Facts for Kids. Sciencekids.co.nz (2012-07-11). Retrieved on 2012-08-21.
- Harding, Brett E.; Wolf, Barbara C. (2006). "Alligator Attacks in Southwest Florida". Journal of Forensic Sciences 51 (3): 674–677. doi:10.1111/j.1556-4029.2006.00135.x. PMID 16696720.
- Living with Alligators, Myfwc.com.
- "A String of Deaths by Gators in Florida". nytimes.com. 2006-05-15. Retrieved 2006-05-15.
- "Alligator wrestling - cruelty or tradition?". BBC News.com. March 17, 2009. Retrieved August 29, 2012.
- Lane, Thomas J.; Ruppert, Kathleen C. (June 2008). "Alternative Opportunities for Small Farms:Alligator Production Review". University of Florida. Retrieved August 29, 2012.
- Reig Eimeric (2006). "Gator Maters: Florida farmers find lucrative business mating alligators". Orange and Blue Magazine. Retrieved August 29, 2012.
- "Calories in Alligator, Crocodile". Annecollins.com. Archived from the original on 18 December 2008. Retrieved 2008-12-11.
- "Alligator". Florida State Symbols. Florida Division of Historical Resources. 2013. Retrieved April 6, 2013.
- "About Louisiana". Louisiana.gov. State of Louisiana. Retrieved April 6, 2013.
- Act No. 302 of 2001. Retrieved on April 6, 2013.
- "History: 1906–1927, early Gainesville". University of Florida. Archived from the original on 31 December 2010. Retrieved February 13, 2011.
|Wikimedia Commons has media related to: Alligator mississippiensis|
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