American alligator, (Alligator mississippiensis), species of alligator inhabiting freshwater rivers, lakes, and swamps and brackish waters in the Southern U.S. and northeastern Mexico. The alligator’s geographic range extends from the Mexican states of Coahuila, Nuevo León, and Tamaulipas northeastward to Oklahoma and Arkansas and eastward through the Gulf Coast to North Carolina, South Carolina, Georgia, and Florida. The species is one of two classified in the genus Alligator, the other being the Chinese alligator (A. sinensis), which inhabits parts of the lower Yangtze River valley in China. The American alligator is one of the best-known and best-studied crocodilians. The name alligator is thought to derive from the Spanish phrase el lagarto, meaning “the lizard.”

　　Natural history The largest adults can grow up to 4.5 meters (15 feet) in length and weigh up to 363 kg (800 pounds), but most are roughly 3–3.4 meters (9.8–11.1 feet) long and weigh about 150 kg (331 pounds), males being slightly larger and heavier than females. American alligators are the darkest colored of all living crocodilians. Juveniles are shaded black with yellow banding, but, as they age, the color fades, and the top and sides of adults change from black to brown and olive-hued black. Their undersides are cream-colored. The alligator’s snout is broad and rounded, and its upper jaw is larger than its lower jaw, which allows its upper jaw to fully cover the teeth of the lower jaw when the mouth is closed. Fully grown American alligators possess between 74 and 80 teeth of similar size, which are quickly replaced should they break or wear down. Some alligators are capable of growing up to 3,000 teeth over the course of their lives.

　　American alligator (Alligator mississippiensis)American alligator (Alligator mississippiensis) entering open water in a wetland near Sarasota, Florida. Alligators live along the edges of permanent bodies of water. They spend most of their time in the water, hunting, but they spend the early part of the day on land, basking in the sun to increase their metabolism.(more)Like its Chinese counterpart, the American alligator is a carnivore and lives along the edges of permanent bodies of water. The species spends most of its time in the water, hunting, but it spends the early part of the day on land, basking in the sun to increase its metabolism. When environmental conditions become either too warm or too cold, the alligator retreats to a large burrow it has excavated in the soil.

　　Predators and prey

　　American alligator (Alligator mississippiensis)American alligator (Alligator mississippiensis) basking on a partially submerged log. Alligators are quick, snatch-and-grab predators that capture prey near the shoreline or in the water, where they often lurk with just their eyes and nostrils breaking the surface. (more)American alligators are apex predators, capable of capturing and eating prey of nearly any size. They are quick, snatch-and-grab hunters that often take their prey in the water, where they often lurk just beneath the surface, or near the shoreline. Adults can reach swimming speeds up to 32.2 km (20 miles) per hour and galloping speeds up to 17.7 km (11 miles) per hour on land. Their diet tends to be made up of a mix of invertebrates, amphibians, turtles, snakes, fishes, including the largemouth bass (see black bass), birds, and mammals, especially the nutria, or coypu. American alligators occasionally set upon people. Indeed, 450 alligator attacks having been documented since 1948. Of these, 26 attacks have resulted in death of the victims, most of whom were swimming, fishing, or provoking the animals.

　　Younger, smaller American alligators are often consumed by birds and predatory mammals—such as raccoons (which also consume alligator eggs), otters, black bears, and bobcats—as well as by larger alligators. Adult American alligators are hunted by human beings, but they may also fall victim to other large predators with which they also compete, including pumas in habitats where their ranges overlap and Burmese pythons, an invasive species that challenges the alligator for dominance in southern Florida.

　　Reproduction Generally speaking, American alligators live in small social groups. However, during the breeding season, which begins in April, males may become increasingly protective of their space and compete with each other for available mates, at times hissing and bellowing at others to stake their claim to mates and the breeding and nesting areas that females have marked with their scent. The species is polygynous, and, while there is evidence of some males mating with up to 10 females during a breeding season, most males breed with 1 female. Females construct a nest of plant debris and rotting vegetation, within which they deposit fertilized eggs during the early summer. Although most clutches contain about 35–39 eggs, some may contain 50 or more.

　　Get a Britannica Premium subscription and gain access to exclusive content. Subscribe Now As the eggs incubate, female alligators defend their nests from egg predators until the young emerge in late August and early September. Eggs are more likely to develop into male alligators when the average nest temperature hovers between roughly 32 and 32.5 °C (86.9 and 90.5 °F). Young will remain in the care of their mother for a year or two before becoming fully independent. During this period, they will join with the young from other clutches in pods protected by multiple females. They typically become sexually mature sometime after age 10, which coincides with the growth of males and females to a length of 1.8 meters (5.9 feet) or more. American alligators live for about 35 to 50 years in the wild but may live for more than 70 years in captivity.

　　Conservation status Since 1996 the American alligator has been classified as a species of least concern by the International Union for Conservation of Nature and Natural Resources (IUCN), despite having been hunted for its skin, teeth, and meat in much of the Southern U.S. since the 1800s. Hunting pressure was so great that the United States classified the alligator as an endangered species in 1967, which allowed its population to recover substantially throughout the next decade. By the 2020s more than 750,000 wild adult alligators were living throughout the species’ range. Although habitat loss and water pollution—along with automobile strikes, flooding, and saltwater intrusion into their freshwater habitats—have claimed the lives of some alligators, ecologists report that populations across the Southern U.S. are either growing or stable. The species is raised commercially on farms and ranches, where its meat and skin are harvested under close regulation.