Information about Caiman

Alligators
An American Alligator in captivity at the Columbus Zoo An American Alligator in captivity at the Columbus Zoo
Scientific classification
Phylum: Chordata Class: Sauropsida Order: Crocodilia Family: Alligatoridae Genus: Alligator Daudin, 1809
Species
Alligator mississippiensis Alligator sinensis

An alligator is a crocodilian in the genus Alligator of the family Alligatoridae. The name alligator is an anglicized form of the Spanish el lagarto ("the lizard"), the name by which early Spanish explorers and settlers in Florida called the alligator. There are two living alligator species: the American Alligator (Alligator mississippiensis) and the Chinese Alligator (Alligator sinensis).

Description

Alligators are characterized by a wider snout than crocodiles. Both living species also tend to be darker in color, often nearly black but color is very dependent on the water. Algae-laden waters produce greener alligators; alligators from waters with a lot of tannic acid from overhanging trees are often darker (although the Chinese alligator has some light patterning.) Also, in alligators only the upper teeth can be seen with the jaws closed (in contrast to true crocodiles, in which upper and lower teeth can be seen), though many individuals bear jaw deformities which complicate this means of identification. The eyes of a large alligator will glow red and those of a smaller one will glow green when a light is shined on them. This fact can be used to find alligators in the dark.

An average American alligator's weight and length is 800 lbs (360 kg) and 13 feet (4 m) long. According to the Everglades National Park website, the largest alligator ever recorded in Florida was 17 feet 5 inches long (5.3 m). The largest alligator ever recorded in Alabama measured 12 feet 8 inches (3.7 m). The largest alligator ever recorded measured 19 feet 2 inches (5.8 m) and was found on Marsh Island, Louisiana. Few of the giant specimens were weighed, but the larger ones could have exceeded a ton in weight. The Chinese Alligator is smaller, rarely exceeding 7 feet (2 m) in length.

An alligator's lifespan is usually estimated in the range of 50 years or more. A specimen named Muja has resided in the Belgrade Zoo in Serbia since 1937, making it at least 70 years old. Another specimen, Čabulītis, in Riga Zoo, Latvia died in 2007 being more than 72 years old.

Habitat

Alligators are native to only two countries: the United States and China.

The American Alligators normally live along the coast of the Gulf of Mexico, Texas, Oklahoma, Louisiana, Mississippi, Alabama, and Florida as well as Arkansas, Georgia and the Carolinas.

The majority of American Alligators inhabit Florida and Louisiana. In Florida alone there are estimated to be more than one million alligators. The United States is the only place where both alligators and crocodiles live side by side. American Alligators live in freshwater environments, such as ponds, marshes, wetlands, rivers, and swamps, as well as brackish environments.

The Chinese alligator currently is found only in the Yangtze River valley and is extremely endangered, with only a couple dozen believed to be left in the wild. Indeed, far more Chinese alligators live in zoos around the world than can be found in the wild. For example, Rockefeller Wildlife Refuge in southern Louisiana has several in captivity in an attempt to preserve the species.

Behavior

Large male alligators are solitary, territorial animals. Smaller alligators can often be found in large numbers in close proximity to each other. The largest of the species (both males and females), will defend prime territory; smaller alligators have a higher tolerance of other alligators within a similar size class.

Although alligators have heavy bodies and slow metabolisms, they are capable of short bursts of speed, especially in very short lunges. Alligators' main prey are smaller animals that they can kill and eat with a single bite. Alligators may kill larger prey by grabbing it and dragging it in the water to drown. Alligators consume food that cannot be eaten in one bite by allowing it to rot or by biting and then spinning or convulsing wildly until bite-size pieces are torn off. This is referred to as the "death roll."

Most of the muscle in an alligator's jaw is intended for biting and gripping prey. The muscles that close the jaws are exceptionally powerful, however the muscles for opening their jaws are relatively weak. As a result, an adult man can hold an alligator's jaw shut with his bare hands. In general, a simple rubber band is enough to prevent an adult alligator from opening its jaws.

Alligators are generally timid towards humans and tend to walk or swim away if one approaches. Unfortunately, this has led humans to the practice of approaching alligators and their nests in a way that provokes them. There are laws against feeding the alligators but some people continue to feed them nevertheless, resulting in some of the alligators losing their fear of humans and in turn, choosing to approach humans instead of moving away.

Diet

Alligators are opportunistic feeders, eating almost anything they can catch. When they are young they eat fish, insects, snails, and crustaceans. As they grow, they take progressively larger prey items, including larger fish such as gar, turtles, various mammals, birds, and other reptiles. Their stomachs also often contain gastroliths. They will even consume carrion if they are sufficiently hungry. Adult alligators can take razorbacks and deer and are well known to kill and eat smaller alligators. In some cases, larger alligators have been known to hunt the Florida panther and bears, making it the apex predator throughout its distribution. As humans encroach onto their habitat, attacks on humans are few but not unknown. Alligators, unlike the large crocodiles, do not immediately regard a human upon encounter as prey.

Attacks on Humans

Human deaths caused by alligators have increased. While there were only nine fatal attacks in the U.S.A. between 1970 and 2000, eleven people were killed by alligators in the five years between 2001 and 2006 alone.

Alligators do tend to be wary of humans, but overconfidence has led some people to enter the animals' habitat in ways that provoke aggression.

Reproduction

The maturity of the alligator is dependent more upon the size of the animal than its age. An alligator is generally considered mature when it reaches a length of six feet (1.8 m) or more. They are seasonal breeders. The mating season is in spring when the water warms. The female builds a nest of vegetation that rots, incubating the eggs. Sex is fully determined at the time of hatching and irreversible thereafter, and depends on the temperature of egg incubation, temperatures of 30 °C (86 °F) producing females, of 34 °C (93 °F) yielding only males. The temperature-sensitive period is between seven and 21 days of incubation. Natural nests constructed on levees are hotter (34 °C) than those constructed on wet marsh (30 °C); thus, the former tend to produce males and the latter, females. The natural sex ratio at hatching is five females to one male. Females hatched from eggs incubated at 30 °C weigh significantly more than males hatched from eggs incubated at 34 °C.[3] The mother will defend the nest from predators and will assist the babies to water once they hatch. She will provide protection to the young for about a year if they remain in the area. The largest threat to young alligators are adults, accounting for nearly a fifty percent mortality rate in some cases.

Incidentally, in the past there have been population explosions of alligators in the years following the outlawing of alligator hunting, as the young gators have a greater chance of surviving to adulthood once much of the previous adult generation had been killed off.

Farming

Alligator farming is a big and growing industry in 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 6-7 foot (1.8-2 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, raw alligator meat contains roughly 200 calories per 3oz (85 g) serving size, of which 27 calories come from fat.^[1]

The Difference Between Alligators and Crocodiles

While alligators are often confused with crocodiles, they belong to two quite separate taxonomic families, and are as distinct from one another as humans are from gorillas.

Alligators differ from crocodiles principally in having wider and shorter heads, with more obtuse snouts; in having the fourth, enlarged tooth of the under jaw received, not into an external notch, but into a pit formed for it within the upper one; in lacking a jagged fringe which appears on the hind legs and feet of the crocodile; in having the toes of the hind feet webbed not more than half way to the tips; and an intolerance to salinity, alligators strongly preferring fresh water, while crocodiles can tolerate salt water due to specialized glands for filtering out salt. In general, crocodiles tend to be more dangerous to humans than alligators.

As for appearance, one generally reliable rule is that alligators have U-shaped heads, while crocodiles are V-shaped. Crocodiles have a longer narrower snout, with eyes farther forward. ^[2]Also, if one looks at an alligator and then a crocodile, one will notice a difference in their mouths: only the upper teeth are visible when an alligator's mouth is closed, while a crocodile's mouth will reveal both upper and lower teeth, as their fourth tooth sticks out from the lower jaw, rather than fitting neatly into the upper jaw. ^[3] Crocodiles also tend to have green eyes, while alligators have brown ones.

Another distinction can be drawn between the jaws of the two animals. Crocodiles' jaws are much more narrow and are used to tear and grip on prey. By contrast, alligators' jaws are meant to crush bones, and can deliver a bite force of up to 3000psi (20MPa).

Media

See also

• List of fatal alligator attacks in the United States by decade

References

External links

• Crocodilian Online
• Everglades National Park Alligators
• Temperature of egg incubation determines sex