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Alligators and Caimans Fossil range: Cretaceous - Recent
American Alligator
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Sauropsida Order: Crocodilia Family: Alligatoridae Gray, 1844
Living Genera
Alligator Caiman Melanosuchus Paleosuchus

Alligators and caimans are archosaurs, small species of crocodilians and forming the family Alligatoridae (sometimes regarded instead as the subfamily Alligatorinae).

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.

Alligators proper occur in the fluvial deposits of the age of the Upper Chalk in Europe, where they did not die out until the Pliocene age.

The true alligators are now restricted to two species, A. mississippiensis in the Southern United States, which grows to an average of 4 m (12 ft), with the record of 5.79 m (19 ft) in length, and the small A. sinensis in the Yangtze River, People's Republic of China, which grows to an average of 1.5 m (5 ft). Their name derives from the Spanish el lagarto, which appears to be a cognate of la lagartija, "the lizard").

In Central and South America, alligators are represented by five species of the genus Caiman, which differs from the alligator by the absence of a bony septum between the nostrils, and the ventral armour is composed of overlapping bony scutes, each of which is formed of two parts united by a suture. Some authorities further divide this genus into three, splitting off the smooth-fronted caimans into a genus Paleosuchus and the Black Caiman into Melanosuchus.

C. crocodilus, the Spectacled Caiman, has the widest distribution, from southern Mexico to the northern half of Argentina, and grows to a modest size of about 2.2 meters. The largest, attaining an enormous bulk and a length of 6 meters, is the near-threatened Melanosuchus niger, the Jacare-assu, Large, or Black Caiman of the Amazon. The Black Caiman and American Alligator are the only members of the alligator family posing the same danger to humans as the larger species of the crocodile family.

Although the Caiman has not been studied in-depth, it has been discovered that their mating cycles (previously thought to be spontaneous or year-round) are linked to the rainfall cycles and the river levels in order to increase their offspring's chances of survival.

An alligator nest at Everglades National Park, Florida.

• ORDER Crocodilia
  • Family Alligatoridae
    • Genus Leidyosuchus (extinct)
    • Genus Deinosuchus (extinct)
    • Subfamily Alligatorinae
      • Genus Albertochampsa (extinct)
      • Genus Chrysochampsa (extinct)
      • Genus Hassiacosuchus (extinct)
      • Genus Navahosuchus (extinct)
      • Genus Ceratosuchus (extinct)
      • Genus Allognathosuchus (extinct)
      • Genus Hispanochampsa (extinct)
      • Genus Arambourgia (extinct)
      • Genus Procaimanoidea (extinct)
      • Genus Wannaganosuchus (extinct)
      • Genus Alligator
        • Alligator prenasalis (extinct)
        • Alligator mcgrewi (extinct)
        • Alligator olseni (extinct)
        • Chinese Alligator, Alligator sinensis
        • Alligator mefferdi (extinct)
        • American Alligator, Alligator mississippiensis
    • Subfamily Caimaninae
      • Genus Necrosuchus (extinct)
      • Genus Eocaiman (extinct)
      • Genus Paleosuchus
        • Cuvier's Dwarf Caiman, Paleosuchus palpebrosus
        • Smooth-fronted Caiman, Paleosuchus trigonatus
      • Genus Purussaurus (extinct)
      • Genus Mourasuchus (extinct)
      • Genus Orthogenysuchus (extinct)
      • Genus Caiman
        • Yacare Caiman, Caiman yacare
        • Spectacled Caiman, Caiman crocodilus
          • Rio Apaporis Caiman, C. c. apaporiensis
          • Brown Caiman, C. c. fuscus
        • Caiman lutescans (extinct)
        • Caiman sorontans (extinct) - Not reported in the literature, probably a nomen nudum
        • Broad-snouted Caiman, Caiman latirostris
      • Genus Melanosuchus
        • Melanosuchus fisheri (extinct)
        • Black Caiman, Melanosuchus niger

South Beach Alligator Farm.

In Native American and African American folklore, the alligator is revered, especially the teeth, which can be worn as a charm against witchcraft and poison.

El hombre caiman (The caiman man) is a legend from the north coast of Colombia.

Often, it is the butt of practical jokes by tricksters like Brer Rabbit.

An urban legend states that full grown alligators exist in the sewers of cities like New York City. According to one version of this story, people buy baby alligators after visiting Florida or other places where they are native, and flush them down the toilet once they get big. Such alligators could not survive, however, because without UV rays from sunlight, alligators cannot properly metabolize calcium, resulting in metabolic bone disease and eventually death. Small released alligators and caimans, though, are occasionally found in northern lakes. See Sewer alligator for more information.

Alligator skin was once a highly prized leather, and was farmed in some areas, as pictured in the panoramic image above. Alligator is sometimes eaten as an exotic meat. Specifically, the alligator's tail is eaten commonly in the southern U.S., especially in Florida.