American Alligator, Alligator mississippiensis
American Alligator, Alligator mississippiensis. Photograph taken within the Everglades National Park, South Florida, February 2021. Photograph courtesy of Carol Snow, Del Mar, California.
American Alligator, Alligator mississippiensis. Photograph taken within the Everglades National Park, South Florida, January 2023. Photograph and identification courtesy of Faith Hubsch, Fort Lauderdale, Florida.
The American Alligator, Alligator mississippiensis, is a member of the Alligatoridae family of alligators. The Alligatoridae family has two subfamilies, Alligatorinae and Caimaninae. The first has eleven genera of which ten are extinct with one living species, this species, placed in the Alligator Genus. The second has seventeen genera of which eleven are extinct with six living species placed in three genera; three in the Caiman Genus, one in the Melanosuchus Genus and two in the Paleosuchus Genus. Globally there are two species in the genus Alligator, of which one is endemic to China and the other is found in the Southeastern United States. The name alligator comes from the Spanish word el lagarto, which means lizard. The American Alligator is known in Mexico as Aligator Americano.
The American Alligator has an “armored” back with embedded plates called osteoderms or scutes. They have a muscular and flat tail and four short and powerful legs. Their front legs have five digits while their back legs have four digits. Their snout is broad and U-shaped with upward facing nostrils that allow breathing to occur while the rest of their body is underwater. When they are underwater, their nostrils and ears close up and a membrane covers their eyes. The American Alligator can have up to 80 teeth in its mouth at a time and when they become worn down or fall out, they are replaced. Over an alligator’s lifetime, it may go through 2,000 to 3,000 teeth. Young alligators have bright yellow stripes on their tails while adults have dark stripes on their tails. Depending on their habitat, the color of the adult alligator varies and can be olive, brown, gray, or nearly black. In algae-laden waters, they may have greener skin while tannic acid from overhanging trees (primarily chestnut or oak) can produce darker skin. Some sexual dimorphism occurs within this species with the males growing larger than the females. At 20 years of age, the male alligators are larger than the females being approximately 3.50 m (11 feet six inches) in length and female alligators being approximately 2.6 m (8 feet 6 inches) in length. On average, males weigh approximately 225 kg (500 lbs) and females 91 kg (200 lbs). Exceptionally large males can weigh upwards of a 454 kg (1,000 lbs). They possess a variety of locomotion including swimming, walking, running, and crawling. Unlike most reptiles, alligators walk with their legs directly beneath them instead of diagonally. This allows them to lift their tails off the ground while they move.
The American Alligator is carnivorous and possesses strong jaws that can crack turtle shells. Their diet consists of fish, snails and other invertebrates, birds, frogs, and mammals that come to the water’s edge. If their prey is small, they swallow it whole. If their prey is large, they shake it apart into smaller, more manageable pieces. For exceptionally large prey, the alligator will perform a “death roll” to subdue and dismember their prey. To perform this spinning maneuver, the alligator bites into their prey and rapidly rotates about the longitudinal axis of their body. If possible, they will also drag large prey underwater to drown them. In addition, they possess an adaptation in their throat called a glottis which allows them to capture prey while completely submerged in water by preventing water from entering their lungs.
Both male and female American Alligators reach sexual maturity when they are about 1.8 m (6 feet 0 inches) in length, which is attained at 10 to 12 years. Courtship starts in April and mating usually occurs in early May with breeding occurring primarily at night in shallow waters. During courtship, males, also referred to as bulls, roar to attract females and ward off other males. After mating, the female builds a nest of vegetation that are approximately 2.1 m (7 feet) to 3.0 m (10 feet) in diameter and 60 cm (2 feet) to 90 cm (3 feet) in height. Females lay between 35 and 50 eggs late June to early July and some can lay up to 90 eggs. The eggs are then covered and guarded by the mother. The sex of the juveniles is determined by the temperature of the nest. Temperatures of 34°C (93.2°F) and above produce mostly males, while temperatures of 30°C (86°F) produce mostly females. At the end of August, the young alligators start to make high-pitched noises inside their eggs which lets the mother know that it is time to remove the nesting material. The eggs then hatch after an incubation period of 65 days. Newly hatched alligators are 15 cm (6 inches) to 20 cm (8 inches) in length and live in small groups called “pods”. The mother then carries her young to the water on her back or in her mouth. Alligator nests are sometimes used by other reptiles for their own egg deposition and incubation once they are abandoned by the female alligators. About 80% of young alligators become prey to predators such as birds, raccoons, bobcats, otters, snakes, large bass, and larger alligators. As a result, females aggressively defend their young during their first few years. Juveniles grow at a rate of 30 cm (1 foot) per year. They consume insects, shrimp, tadpoles, frogs, and small fish. After they are 1.2 m (4 feet) in length, the young alligators are generally safe from predators except humans and occasionally other larger alligators. The American Alligators have life spans of fifty years in the wild.
Although they do not hibernate, the American Alligator undergoes periods of dormancy when the weather becomes cold. In areas where the water level fluctuates, alligators dig themselves into hollows in the mud which fill with water when the water level rises. These tunnels, or “gator holes”, can be 20 m (65 feet) in length and provide shelter during extreme hot or cold weather. After the hollows are abandoned, they provide habitat for fish and water holes for birds and other animals.
From a conservation perspective the American Alligator is currently considered to be of Least Concern, with stable, widely distributed populations. Once hunted for its meat and skin, the American Alligator population decreased dramatically and they were placed on the endangered species list in 1967. After this placement, their populations have steady increased.