The American alligator (Alligator mississippiensis), also called the common alligator or gator, is a large reptile found in the southeastern United States. It is one of two living species in the genus Alligator and is larger than the other living alligator species, the Chinese alligator.

Adult male American alligators grow to be 3.4 to 4.8 meters (11.2 to 15.7 feet) long and can weigh up to 900 kilograms (2,000 pounds). Some unconfirmed reports suggest they may reach lengths of 5.84 meters (19.2 feet) and weigh up to 1,000 kilograms (2,200 pounds), making them the second-longest and heaviest members of the alligator family, after the black caiman. Female American alligators are smaller, measuring 2.6 to 3.35 meters (8.5 to 11.0 feet) in length. These reptiles live in freshwater wetlands, such as marshes and cypress swamps, in areas from southern Oklahoma and Texas to North Carolina. They can be distinguished from the American crocodile by their broader, U-shaped snout, overlapping jaws, and darker color. Unlike the American crocodile, they are less able to live in saltwater but can survive in cooler climates.

American alligators are top predators and eat fish, amphibians, reptiles, birds, mammals, and other alligators. Baby alligators mostly eat insects and other small creatures. They help shape wetland ecosystems by creating alligator holes, which provide wet and dry habitats for other animals. During the year, especially during the breeding season, alligators make loud noises to mark their territory and find mates. Male alligators use low-frequency sounds to attract females. Eggs are laid in nests made of plants, sticks, leaves, and mud near water. Baby alligators are born with yellow stripes and are protected by their mothers for up to one year. This species shows parental care, which is uncommon for most reptiles. Mothers guard their eggs during incubation and carry hatchlings to water with their mouths. Parental care continues for up to three years after birth.

The American alligator is listed as Least Concern by the International Union for Conservation of Nature. In the past, hunting nearly wiped out their population, and they were declared an endangered species in 1973 under the Endangered Species Act. Conservation efforts helped their numbers recover, and they were removed from the endangered list in 1987. This species is the official state reptile of Florida, Louisiana, and Mississippi.

History and taxonomy

The American alligator was first named in 1801 by French scientist François Marie Daudin as Crocodilus mississipiensis. In 1807, scientist Georges Cuvier created the group name Alligator for it, using the English name "alligator," which comes from the Spanish phrase el lagarto, meaning "the lizard."

The American alligator and its closest living relative, the Chinese alligator, belong to the subfamily Alligatorinae. This subfamily is closely related to the group of animals called caimans, which are part of the subfamily Caimaninae. Together, these two groups form the family Alligatoridae, as shown in this diagram:

Ceratosuchus burdoshi (extinct)
Hassiacosuchus haupti (extinct)
Wannaganosuchus brachymanus (extinct)
Arambourgia gaudryi (extinct)
Allognathosuchus polyodon (extinct)
Allognathosuchus wartheni (extinct)
Procaimanoidea kayi (extinct)
Alligator prenasalis (extinct)
Alligator sinensis (Chinese alligator)
Alligator mississippiensis (American alligator)

Fossils that look exactly like the American alligator have been found from the Pleistocene period, which lasted from 2.5 million to 11,700 years ago. In 2016, a skull from the Late Miocene period, about 7 to 8 million years ago, was found in Marion County, Florida. This skull was nearly identical to the skull of the modern American alligator. Scientists believe this ancient alligator and the modern American alligator are closely related, showing that the Alligator mississippiensis lineage has existed in North America for 7 to 8 million years. However, in 2020, a study suggested that older fossils previously thought to be American alligators were actually different species, Alligator mefferdi and Alligator hailensis, and that the American alligator evolved later, during the Middle Pleistocene.

In the 1990s, scientists mapped part of the alligator’s genetic code, called the mitochondrial genome. This showed the alligator evolved at a rate similar to mammals but faster than birds and most cold-blooded animals. However, a full genome study published in 2014 found that the alligator evolved much more slowly than mammals and birds.

Characteristics

American alligators can be long and thin or short and strong. This might be because of differences in how fast they grow, what they eat, and the weather where they live.

The American alligator is a large type of crocodile. On average, it is the largest in its family, Alligatoridae, except for the black caiman, which might be slightly bigger. Their weight depends on their length, age, health, the season, and the food available. Like many reptiles that live in cooler areas, alligators in northern parts of their range, such as southern Arkansas, Alabama, and northern North Carolina, tend to be smaller. Large adult alligators are usually strong and bulky compared to other crocodiles of similar length. For example, male alligators in captivity that are 3 to 4 meters (9 feet 10 inches to 13 feet 1 inch) long weigh between 200 to 350 kilograms (440 to 770 pounds). However, captive alligators may weigh more than wild ones because they do not face the same challenges, like hunting.

Large male alligators can grow up to 4.6 meters (15 feet 1 inch) long and weigh up to 900 kilograms (2,000 pounds). Females usually reach a maximum length of 3 meters (9 feet 10 inches). The largest recorded female was 3.35 meters (11 feet) long and weighed 147 kilograms (324 pounds). Occasionally, very old male alligators may grow even longer.

During the 19th and 20th centuries, some males were reported to be 5 to 6 meters (16 feet 5 inches to 19 feet 8 inches) long. The largest recorded alligator was a male killed in 1890 in Louisiana, which was said to be 5.84 meters (19 feet 2 inches) long. However, no preserved sample was kept to confirm the size. If accurate, this alligator would have weighed about 1,000 kilograms (2,200 pounds). In Arkansas, a male alligator measured 4.04 meters (13 feet 3 inches) long and weighed 626 kilograms (1,380 pounds). The largest reported alligator in Florida was 5.31 meters (17 feet 5 inches) long, but this record is not confirmed. The largest scientifically verified alligator in Florida between 1977 and 1993 was 4.23 meters (13 feet 11 inches) long and weighed 473 kilograms (1,043 pounds). Another alligator, estimated from its skull, may have been 4.54 meters (14 feet 11 inches) long. The largest alligator killed in Alabama was 4.5 meters (14 feet 9 inches) long and weighed 458.8 kilograms (1,011.5 pounds). This alligator holds the SCI world record from 2014.

American alligators rarely reach these extreme sizes. Most adult males grow to about 3.4 meters (11 feet 2 inches) long and weigh up to 360 kilograms (790 pounds). Adult females typically grow to about 2.6 meters (8 feet 6 inches) long and weigh up to 91 kilograms (201 pounds). In Newnans Lake, Florida, adult males averaged 73.2 kilograms (161 pounds) in weight and 2.47 meters (8 feet 1 inch) in length, while adult females averaged 55.1 kilograms (121 pounds) and measured 2.22 meters (7 feet 3 inches). In Lake Griffin State Park, Florida, adult alligators weighed an average of 57.9 kilograms (128 pounds). At sexual maturity, alligators weigh about 30 kilograms (66 pounds), and adult alligators weigh up to 160 kilograms (350 pounds).

It is commonly believed that crocodiles, including alligators, grow throughout their entire lives. However, this idea is based on observations of young crocodiles, and recent studies suggest this may not be true. For example, a study in South Carolina from 1979 to 2015 found that male alligators stop growing at about 43 years old, and females stop growing at about 31 years old.

American alligators show some size differences between males and females, but this is not as extreme as in other crocodile species, like saltwater crocodiles, where males are nearly twice as long and four times as heavy as females. Female alligators have higher survival rates as young, and many populations include many young or immature alligators. This means that large, mature males are rarely seen.

Adult alligators have dark upper bodies that can be olive, brown, gray, or black. They are among the darkest-colored crocodiles, and their dark scales help distinguish them from crocodiles, which have lighter scales. Their underbellies are cream-colored. Some alligators lack a pigment called melanin, making them albino. These alligators are very rare and cannot survive in the wild because they are vulnerable to sunlight and predators.

American alligators have 74 to 80 teeth. As they grow, their teeth and jaws change. Juveniles have small, needle-like teeth, and their snouts become broader as they mature. These changes match shifts in their diet, from eating small prey like fish and insects to larger prey like turtles, birds, and other animals. Alligators have broad snouts, especially in captivity. When their jaws are closed, the lower teeth fit into hollows in the upper jaw. Like the spectacled caiman, alligators have a bony ridge on their nose, though it is not as noticeable. Alligators are often mistaken for American crocodiles, but the fourth tooth on an alligator’s upper jaw is hidden in a pocket when the mouth is closed. Alligators replace their teeth about once a year, and over their lifetimes, they can have more than 2,00

Distribution

American alligators live naturally in the Nearctic and Neotropical regions. In the wild, they are found in the southeastern United States, from the Lowcountry in South Carolina, south to Everglades National Park in Florida, and west to South Texas. They also live in parts of North Carolina, South Carolina, Georgia, Florida, Louisiana, Alabama, Mississippi, Arkansas, Oklahoma, and Texas. Some of these areas have alligator populations that appeared recently, even though the groups are small, they can reproduce. Louisiana has the largest American alligator population in any U.S. state. In the future, American alligators may live in parts of Mexico near the Texas border. Their range is slowly growing northward, including places they previously considered too cold, such as Virginia. Alligators have naturally expanded into Tennessee and have a small population in the southwestern part of the state, as reported by the state’s wildlife agency. They no longer live naturally in Virginia, and some alligators from North Carolina occasionally wander into the Great Dismal Swamp.

In 2021, an American alligator was found in Calvert County, Maryland, near Chesapeake Bay. It was shot and killed by a hunter using a crossbow. Other reports of alligators in this area exist, but they are believed to be escaped or released pets.

Conservation status

American alligators are listed as least concern by the IUCN Red List, even though from the 19th century to the mid-20th century, humans hunted and poached them in a way that was not sustainable.

In the past, hunting and the loss of their habitats greatly reduced the number of American alligators in their natural areas. At one time, people were unsure if the species would survive. In 1967, the American alligator was placed on the endangered species list (under a law that was the earlier version of the Endangered Species Act of 1973) because it was believed to be at risk of disappearing from much of its range.

The United States Fish and Wildlife Service (USFWS) and state wildlife agencies in the southern United States helped the American alligator population recover. Protection under the Endangered Species Act allowed the species to grow in areas where it had been greatly reduced. States started tracking their American alligator populations to make sure they continued to increase. In 1987, the USFWS removed the animal from the endangered species list because it was considered to have fully recovered. The USFWS still controls the legal trade of American alligators and their products to protect other endangered crocodilians that might be mistaken for American alligators during illegal trade.

American alligators are listed under Appendix II of the Convention on International Trade in Endangered Species (CITES), which means that international trade in the species (including parts and products made from them) is controlled.

Habitat

American alligators live in swamps, streams, rivers, ponds, lakes, and wetland prairies that have shallow water and canals with nearby levees. One alligator was seen living in a river near Atlanta, Georgia, for more than 10 years. Female and young alligators are also found in Carolina Bays and other wetlands that fill with water seasonally. Although they usually live in fresh water, American alligators may sometimes enter brackish water, but they cannot survive in salt water as well as American crocodiles. This is because the salt glands on their tongues do not work effectively in salt water. A study in north-central Florida found that male alligators prefer open lake areas in the spring, while females use both swampy and open-water areas. In summer, males still stay in open water, but females stay in swamps to build nests and lay eggs. During winter, both males and females may rest in areas under riverbanks or near groups of trees.

In some places, American alligators live near human areas, such as golf courses, because these places have plenty of water and many prey animals like fish and birds.

Recent research shows that young alligators can change their behavior to survive in stressful environments with high salt levels. Instead of changing their bodies, young alligators adjust by basking in the sun or moving between different habitats to avoid becoming dehydrated. As sea levels rise, it is important for alligators to adapt and keep their bodies working properly in changing environments.

American alligators are better at surviving cold weather than American crocodiles. If water reaches 45 °F (7 °C) or colder, American crocodiles would quickly become too cold and drown, but American alligators can stay in such water for a long time without showing discomfort. They control their body temperature by producing heat inside their bodies, which helps them stay warm. This ability allows American alligators to live farther north than American crocodiles. In fact, American alligators are found farther from the equator than any other crocodile-like animal and are better at handling cooler weather. When water freezes, American alligators enter a resting state called brumation. During this time, they push their snouts through the ice to breathe and can stay in this state for several days.

Ecology and behavior

American alligators often bask on land, but they may also climb trees to rest if no shoreline is available. This behavior is rare because alligators usually return to water quickly if they feel threatened.

American alligators change wetland areas, especially in flat places like the Everglades, by digging small ponds called alligator holes. They also dig tunnels in banks and build dens above water with air access. This behavior makes alligators a keystone species. Alligator holes hold water during dry seasons and provide shelter for aquatic animals, helping them survive until rains return. These holes also create drier areas for other reptiles and plants to live. In the Everglades, alligator holes vary in size depending on the type of land they are on. When alligators dig nesting areas, the raised soil helps reptiles and birds nest during floods and supports plant growth in wet areas. Alligators are important in the Everglades, acting as "ecological engineers" that help the ecosystem thrive.

American alligators eat a variety of animals, including Florida gar, pleco, swimmer crabs, redhead ducks, great blue herons, and feral pigs. Their teeth are designed to grip prey but cannot chew like the teeth of dogs or cats. Instead, they use their gizzard and swallow rocks to grind food. As adults, alligators can eat large mammals and crush turtle shells. Their palate allows them to catch prey underwater without breathing in water.

American alligators sometimes use sticks and branches to lure birds. This makes them one of the first reptiles known to use tools. They place sticks on their heads to attract birds looking for nesting materials. This behavior is most common during nesting seasons and has been seen in zoos and parks. However, a 2019 study found that alligators did not use sticks more often near bird nesting areas, suggesting the purpose of this behavior is unclear.

Baby and young alligators face dangers from predators like herons, egrets, otters, snakes, raccoons, fish, and other alligators. Most of their food comes from fish and other aquatic animals near water, which they hunt day or night. Adult alligators also hunt on land, up to 160 feet from water, ambushing animals on trails and roads. They often pull prey into water when hunting on land.

Recent videos show alligators eating sharks and rays, including bonnetheads, lemon sharks, Atlantic stingrays, and nurse sharks. Sharks also prey on alligators, showing that they often interact. Alligators are top predators in their habitats, eating many animals depending on their size and the availability of prey. Hatchlings mostly eat insects, snails, and small fish, while adults eat larger animals like turtles, snakes, and mammals. Common prey includes largemouth bass, spotted gar, frogs, and raccoons. In Louisiana, nutria are often eaten by adult alligators.

If their usual food is not available, alligators may eat dead animals or objects like rocks and bottle caps. These items help them break down meat and bones. Large mammals like deer or wild boars are rarely eaten but may be hunted when smaller prey is scarce. Alligators occasionally eat bobcats, but this does not harm bobcat populations. There is little evidence that alligators prey on nilgai or manatees. In the 2000s, alligators were seen eating invasive Burmese pythons in the Everglades, possibly helping control their spread. However, pythons sometimes hunt alligators too. Alligators rarely eat Florida panthers or black bears, but such events have been recorded.

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Relationship with humans

American alligators can hurt or kill humans, but such attacks are very rare. Attacks may happen if a person is mistaken for prey, especially in or near cloudy water. American alligators are usually less aggressive than crocodiles, which are bigger and some types, like Nile and saltwater crocodiles, may attack humans more often. Alligator bites are serious because of their strong bite and the risk of infection. Even with medical care, a bite can sometimes lead to a deadly infection.

As human populations grow and people build homes in low-lying areas or spend time near water, humans and alligators may come into contact more often. From 1948 to 2004, there were 376 recorded injuries and 15 deaths from alligator attacks in Florida and other parts of the United States. In Florida alone, 257 attacks were reported between 1948 and 2004, with about five attacks each year. Around 23 of these attacks resulted in death. Between 1970 and 2007, 28 fatal attacks occurred in the United States. In 2006, three people in Florida were killed by alligators in less than a week.

Alligator wrestling has been a form of entertainment since the late 1800s. It was first created by the Miccosukee and Seminole tribes for food and later became popular as a tourist activity. Some people criticize this practice, but it remains a tradition.

Alligator farming is a growing industry in Georgia, Florida, Texas, and Louisiana. These states produce about 45,000 alligator hides each year. Hides from alligators that are 6–7 feet (1.8–2.1 meters) long can sell for $300 each. The demand for alligator meat is also increasing, with about 300,000 pounds (140,000 kilograms) of meat produced annually. According to the Florida Department of Agriculture and Consumer Services, raw alligator meat has 232 calories (0.97 kJ) per 3.2-ounce (91 gram) serving, with 38 calories (0.16 kJ) coming from fat.

Culture

The American alligator is the official state reptile of Florida, Louisiana, and Mississippi.

The nickname "Gators" has been used for the University of Florida's sports teams since 1911. In 1908, a printer made a sudden decision to print an alligator emblem on a shipment of the school's football pennants. The mascot became popular and was officially named in 1911, maybe because the team captain was called "Gator." Allegheny College and San Francisco State University also use "Gators" as their mascots.

The Gator Bowl is a college football game held in Jacksonville every year since 1946. The event was hosted at Gator Bowl Stadium until 1993. The Gatornationals is an NHRA drag race held at Gainesville Raceway in Gainesville since 1970.