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Bio Facts: Alligator, American

Alligator, American
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Common Name:

American Alligator

Scientific Name:

Alligator mississippiensis

Family:

Alligatoridae

Order:

Crocodylia

Class:

Reptilia

Range:

Southeastern United States, from North Carolina south to Florida and west to Texas.

Habitat:

Freshwater lakes, ponds, rivers, bayous, marshes, roadside ditches and other bodies of freshwater around Florida, the Gulf and the Lower Atlantic Coastal Plains.

Description:

Alligators reach an average length of between 6 and 10 feet, with males rarely reaching 12 to 14 feet. The tail length is roughly half of their overall length. Their general coloration is uniformly dark, but the light markings of youth may persist into early adulthood. Young alligators have bold yellowish crossbands on a black ground color and are about 9 inches at hatching. Alligators have blunt, rounded snouts.

Life Expectancy:

Approximately 40 years in the wild and 50 years in captivity; estimated ages of up to 103 years recorded on captive individuals.

Sexual Maturity:

Approximately 6 to 10 years

Diet:

In the wild, young alligators eat a variety of small aquatic vertebrates and invertebrates. Adults eat primarily fish, snails, turtles, snakes, and waterfowl. Larger mammals are occasionally taken as well. In the Zoo, they are fed whole and quartered raw chickens and skinned nutria when available. Young alligators are fed pinky mice.

Status:

CITES II, Species of Special Concern (FL), Threatened Due to Similar Appearance (AR, GA, LA, NC, SC).

Behaviors:

Adult alligators are usually solitary, but can become quite social during certain periods. At dusk, they become more active, but activity can be seen during all periods of the day. Peak levels of courtship, for instance, occur in the early morning. An alligator will eat any animal it can overcome. Hunting strategies include waiting unseen for prey to stray too close or moving slowly toward prey without being detected. Large animals are usually taken while drinking at the water’s edge.
Alligators swim with their legs tucked against their body, moving forward quietly by sweeping their powerful tail from side to side. While swimming on the surface of the water, an alligator can often approach its prey without being noticed because it so closely resembles a floating log.

While an alligator is swimming on the surface, only its head and part of its back are visible. Important senses are still at work – it can breathe, see, hear, and smell.

When an alligator cruises around slowly and submerges simply to disappear or rest beneath the water, it can remain there from one to several hours, provided it stays still or moves slowly. More activity or higher temperatures require the alligator to surface more often in order to breathe. During exceptionally cool weather, alligators have stayed submerged for more than eight hours.

“Gator holes” sustain the alligators during droughts or in the winter when water levels decline and their normal habitat dries up dramatically. Alligators find natural depressions in the limestone bedrock and clear out the damp mud with their feet and snouts as they wallow deeper to keep moist. In this way, small ponds are formed, typically ten to twenty feet across and a few feet deep. These areas are vital to the survival of fish and amphibians that congregate in high densities in the gator holes during times of drought. Birds, reptiles, and mammals are also dependent upon these areas as a source for water.

Alligators like to wander during the wet summer season, but they often return to the same holes in winter, cleaning them out to prevent them from silting over. If water levels drop too low, alligators may wander several miles over land in search of suitable habitat.

The breeding season corresponds to warming temperatures and lengthening days from mid-April through mid-May. Water levels and temperatures can affect breeding and nesting activities. As courtship progresses, one alligator will allow close and peaceful approach by another of the opposite sex. Courting pairs may swim in the same vicinity for several days prior to mating and may even sun together. The female will allow a male to stroke her back or head with his forearm. Usually the smaller female will swim to the male, and she will try to press the male underwater. If she is able to accomplish this without the male pressing her underwater, she will leave the area in search of another mate. The female may swim around the male, touching or bumping his head or neck. Either may submerge to blow a stream of bubbles past the other’s head. Eventually, the male swims along side the female, bending his body and tail beneath hers while holding onto her neck with one forelimb. Both submerge, and copulation occurs underwater. The two may remain in the same vicinity for a short while after mating. Both sexes may mate with several partners during the same season.

About two months after mating, the female builds her nest by scraping together a mound of earth and plant debris about two to three feet high and six to seven feet in diameter. When she is ready, she digs a hole in the nest mound with her back feet, straddles the nest and lays between 15 and 60 eggs in the cavity of the nest, using her hind feet to break the fall of the eggs. Most female alligators in the wild begin reproducing at eight to ten years of age, but under ideal conditions, they can reproduce a few years earlier.

The female alligator guards her nest carefully, spending many hours resting with her chin on top of it. If an intruder approaches, she turns to face the threat, hisses, and lunges with an open mouth if the intruder comes too close. The female stays on or very near the nest until the young are ready to hatch, and she often assists the babies in escaping from the nest and eggs. The young may stay near their nest area for up to a year, but as they grow older, adult females will chase them from the area, as they are a threat to any newly hatched babies. As they reach maturity, they will roam widely in search of suitable habitat not occupied by larger alligators. Females between the ages of 5 and 10 years of age will establish a nesting territory and rarely roam more than 0.5 miles away from this site. Males usually wander more, and may have a home range of 2,000 acres.

Alligators change their dietary habits as they age. The young feed primarily on aquatic invertebrates, small fish and frogs. As they grow older, they eat larger frogs, snakes, small rodents and fish. Mature adults eat primarily fish, turtles, snakes, wading birds, and small mammals. They will catch muskrats, turtles, waterfowl and small mammals that get close to the water’s edge, preferring to gulp down these small portions whole. Very large alligators may occasionally pull in and drown larger mammals such as deer or wild pigs, but even adults may continue to feed on insects.

Vocalizations change as juveniles mature. Grunts are replaced with hisses, head slaps, and bellows. Hisses are created as the alligator passes air through its throat. Head slaps are magnificent displays in which the alligator raises its head and tail several feet out of the water, then quickly opens its mouth and slams its entire head down onto the surface of the water, making a loud splash. Immediately after the splash, the males thrash their tails violently from side to side and emit a low growling noise. They may produce the water dance as well, a series of sub-audible “pulses” of sound so strong that they cause the water to literally “dance” in droplets 10 or 15 inches off the surface of the alligator’s back. This head slap is often heard at the onset of the mating season and is associated with males staking out territories. Bellows sound like the rumbling of thunder and can be heard up to half a mile away. To bellow, the alligator assumes a high floating posture with its head and tail elevated above the surface, and then it produces the sub-audible vibrations and the water dance, followed a few seconds later by the low bellow.

Alligators also communicate by watching each other. Usually a hierarchy exists. Larger, more powerful alligators, simply by their presence, induce smaller ones to give up sunning or resting spots. Subtle changes in an alligator’s posture, such as raising the body slightly above the water’s surface, can have unmistakable meanings. Dominant individuals consistently display more of their body above the surface, while subordinate animals will sink below the surface as dominant animals approach. This clear social signaling prevents many “negative” encounters, reducing the chance of injury.

Adaptations:

Sharp teeth, claws, and tough, scaly skin add both protection and efficiency as predators.
Alligators are often seen dragging themselves forward on their bellies as they slide off a bank into the water. For this reason, many people do not know that alligators usually get around on land by raising their bellies off the ground and walking on all four legs. They can also run, and some crocodilians have even been known to gallop for short distances. They are not adapted for running long distances, but are capable of sudden bursts of speed, either to retreat into the water or to charge out of the water and onto shore to grab a morsel such as a discarded fish. A nesting female usually charges anyone who walks too close to her nest.

Alligator jaws are designed for catching, killing, and hanging on to prey and not for chewing food. Alligators swallow small morsels whole and will dismember larger prey. Like a bird, the alligator ingests stones and pebbles to aid in breaking down food particles for digestion. The stones are held in a pouch-like muscular portion of the stomach.

The eyes of an alligator sit well back on the top of the head so that they can take in a wide field of view. Alligators have excellent vision, even at night. Their eyes have two sets of eyelids. The outer set closes like ours, from top to bottom. The inner eyelid, called the “nictitating membrane,” closes from rear to front and is transparent. This membrane covers and protects the sensitive eyeball like built-in goggles, permitting the gator to see clearly underwater.

Crocodilians possess a four-chambered heart that provides more efficient blood circulation. The more complex circulatory system is beneficial when alligators stay submerged for long periods. While they hold their breath, blood is routed through the heart to bypass the lungs as no fresh oxygen can be added to the blood supply. This conserves oxygen for the remaining organs. The amount of time an alligator can stay submerged depends on the animal’s size and the temperature of the water. On warm days, they can stay underwater for approximately 45 minutes. On cooler days, their metabolism slows, and they may stay submerged for much longer periods of time.

Socketed teeth that grow from openings in the jawbone are conical, with a hollow root. The exposed portion of the tooth is solid. New teeth begin forming inside the hollow root of the older teeth, and will eventually replace them at regular intervals. Alligators may grow more than 3,000 teeth during their lifespan.

Crocodilian brains possess a small cerebral cortex, the part of the brain that controls conscience thought, an adaptation that adds efficiency and survivability in the wild.

Egg shells have two layers: 1) the outer part is hard and thick like a chicken egg, and 2) the inner layer is a thick membrane. During the seventh week of incubation, the shell begins to develop a network of tiny cracks. It is thought that bacteria from the moist nest aids in the deterioration of the tough outer shell. Just before hatching, a small “egg tooth” develops on the end of the baby’s snout. When incubation is complete, the baby uses its egg tooth to tear through the membrane.

Special Interest:

There are twenty-three species in eight genera of crocodilians. Twenty species are listed as Endangered with the USFWS.
Crocodiles and alligators are descended from socket-toothed reptiles called Thecodonts that lived more than 200 million years ago. Some extinct crocodilians were true giants measuring close to 50 feet long.

Alligators lack sex chromosomes. The sex is actually determined by the temperature at which their eggs incubate. This phenomenon is called TDSD, temperature-dependent sex determination. In an alligator nest, the eggs that incubate between 90 and 93 degrees become males, while those incubating between 82 and 86 degrees become females. Since the eggs at the top of the alligator’s nest are likely to be heated more by the sun than those below, males usually come from the top part of the nest while females come from the bottom. A baby’s sex is determined during the first three weeks of incubation.

Alligators belong to a family closely related to the crocodiles and look very similar. The alligator’s head is much broader and the snout blunter than the crocodile’s. When an alligator’s mouth is shut, the upper teeth lie outside and cover the lower ones, whereas the crocodile’s teeth “mesh” together, with both upper and lower teeth visible. This overlapping of the upper teeth tends to give an alligator the illusion of smiling. On both alligators and crocodiles, the lower tooth fourth from the front is enlarged, but unlike the crocodile’s, which fits into a notch in the upper jaw and is visible, the alligator’s is not noticed as it fits into a socket when the mouth is shut.

Folklore:

In the past, baby alligators could be bought as pets. Eventually tiring of their new pets, as the story goes, owners would flush the little animals down the toilet, supposedly creating huge populations of alligators in the sewers of New York and other cities. Don’t believe it!
The name “alligator” comes from the Spanish “el largato”, “the lizard.”

In Louisiana, a bagful of alligator teeth was thought to prevent warts. Rubbing oil from an alligator on a person’s skin was thought to ease the pain of rheumatism, and ashes from a burned alligator skin were thought to produce a narcotic effect.

The use of “alligator” as a reference to a “friend” or “acquaintance” became famous in the expression, “See ya later, alligator!” The correct response is, “After while, crocodile!”

The Choctaw Indians tell this tale of how the alligator taught their people to hunt:

A Choctaw hunter always had very bad luck while hunting in spite of the fact that he was skilled and had strong, straight arrows. He finally decided that he would succeed at hunting or lose his life trying. He hunted for three days until he came upon a dried-up pond, in the center of which was an alligator stranded in the mud and unable to move for lack of water. The hunter took pity on the alligator and helped it to water. In return the alligator gave the hunter these instructions on how to become a great hunter: You will soon meet a young doe. Do not kill her, for it is not even old enough to have young yet. Then you will meet a large doe, but do not kill her either, for she will have many fawns. Next you will meet a young buck, but do not kill him, for he will father many fawns. Finally, you will meet a large buck whose time on Earth will be nearly up. Kill this buck quickly and mercifully, asking forgiveness and offering thanks. The hunter did as he was instructed and soon became the greatest hunter of the tribe. He taught all of his people how to hunt in this manner, and as long as they followed his teachings, the Choctaw were never hungry.

Conservation:

Many of the early settlers of the SE United States considered alligators to be a nuisance and killed them to protect livestock and for sport. In 1855, France discovered that alligator hides could be fashioned to make durable and fashionable shoes and saddlebags. With the outbreak of war in France in 1861, the overseas trade in alligators ceased. In 1870 after the war, several U.S. tanneries began processing alligators. Between 1870 and 1965, tannery records indicated that some 10 million alligators had been processed. This number is suspected to be higher. Nearly 2.5 million skins passed through tanneries from 1881 to 1891. With the dwindling populations of alligators, the price for their hides skyrocketed from 13¢ per foot in 1916 to $23 per foot in 1986.
By 1960 it was evident that overhunting and habitat loss were taking their tolls on the alligator population. Babies were being sold to tourists or shipped to pet stores in the North. Many died from pneumonia or calcium deficiencies. By the early 1960’s, about the only place one could see an alligator in the wild was in a few of the wildlife parks and refuges. Laws were implemented to protect the now dangerously small alligator populations.

In 1961, Florida outlawed the hunting of alligators. Louisiana followed suit in 1966. The demand for alligator skins was at an all time high. Shoes cost between $70 and $350 a pair, handbags sold between $150 and $250 each, and luggage went for $1,000 each piece. Poaching of alligators became a million dollar business. By 1968, it was estimated that 97% of all alligator goods came from illegal sources. South Florida conservation officers estimated that between 20,000 and 50,000 alligators were illegally slaughtered annually. Even though protected in 95% of its range in the United States, the alligator was added to the Endangered Species list in 1967.

Traffic in hides did not begin to taper off until laws were passed to stop tanners and marketers of alligator goods. In 1969, New York passed the Mason-Smith Act that banned the sale of endangered species and their products within the state. Pennsylvania, Massachusetts, Connecticut, and California followed suit and passed similar laws. The Lacey Act was amended by Congress to prohibit the interstate trade in reptile hides obtained illegally. These laws forced tanners to begin exploiting foreign sources of hides – caimans and crocodiles from Central and South America, Africa, and SE Asia. Most of these species are now endangered. The Lacey Act also made importing poached hides or those exported from illegal sources unlawful. Yet, in the late 1960’s and early 1970’s, American tanners were importing 75,000 hides annually. Not until CITES and the United States Endangered Species Act were ratified and passed in 1973 did the trade in illegal crocodilian hides diminish.

Well over twenty pages of Florida’s Fish and Wildlife statutes and regulations address the harvest and possession of the wild American alligator wild caught in the state. At present, the collecting or killing of alligators is strictly regulated. In Florida, hunters obtain permits through an annual drawing, after which they are informed of how many and where they may hunt. Other laws regulate the collection of eggs and the removal of nuisance alligators. The intentional feeding or enticing with feed of any wild alligators is prohibited except as authorized.

The only other species of alligator in the world is found in China, but it is smaller and quite rare. Critically endangered, the Chinese alligator’s wild population today only numbers about one hundred. It is found principally in the freshwater habitats of the Anhui and Jiangxi provinces located along the Chang Jiang (Yangtze) River Basin in eastern China. Western man did not discover it until 1879 and little has been written about it.

Jacksonville Zoo History:

There were probably alligators at the Zoo when it opened on May 12, 1914. We know for sure that there were two alligators in the animal collection on December 31, 1914. There have probably always been American alligators in the Jacksonville Zoo’s collection. It is unclear whether this species has ever bred here.

Last Revised:

2001