caiman

also n., pl. -mans.

Any of various tropical American crocodilians of the genus Caiman and related genera, resembling and closely related to the alligators.

[Spanish caimán, from Carib acayuman.]

(Alligatoridae)

Class: Reptilia

Order: Crocodylia

Suborder: Eusuchia

Family: Alligatoridae

Thumbnail description
Powerful animals with a long and muscular tail, four short limbs straddling a scaly body, and strong jaws lined with obvious teeth

Size
4–20 ft (1.2–6 m) in total length

Number of genera, species
4 genera; 8 species

Habitat
Calm or slow-moving freshwater areas

Conservation status
Critically Endangered: 1 species; Lower Risk/Conservation Dependent: 1 species

Distribution
Central to northern South America, parts of southern and western Central America and Mexico, the southeastern United States, and a small area of eastern China

Evolution and systematics

Although the order Crocodylia dates back at least 200 million years to the Age of Reptiles, its living members, including those of the family Alligatoridae, can hardly be described as primitive. Instead, they survived the mass extinction 65 million years ago that ended the dinosaurs' reign and evolved over the centuries into animals well suited to their current place in the natural world. Like other members of the order, the family Alligatoridae are the descendants of the Archosauria, or "ruling lizards," which included the dinosaurs. A defining characteristic of these animals is a diapsid skull, which has two temporal openings. Turtles, by comparison, have anapsid skulls with no temporal openings.

Within the crocodilians, the family Alligatoridae can be followed as far back as the Paleocene (57–65 million years ago), when caiman ancestors are thought to have roamed the earth. Ancestors of other species, including the American alligator (Alligator mississippiensis) and Chinese alligator (Alligator sinensis), date back to the Miocene and Pleistocene, respectively. The alligatorids are separated into two major groups: the alligators (subfamily Alligatorinae) and the caimans (subfamily Caimaninae). The former group has two living representatives in the Alligator genus. The other six species of alligatorids fall under three genera within the caimans. (Some systematists list only five caimans, with the Yacaré as a subspecies of the common caiman.) In all, the eight species are as follows:

• American alligator, Alligator mississippiensis
• Chinese alligator, A. sinensis
• common caiman, Caiman crocodilus
• broad-snouted caiman, C. latirostris
• Yacaré, C. yacare
• black caiman, Melanosuchus niger
• Cuvier's dwarf caiman, Paleosuchus palpebrosus
• smooth-fronted caiman, P. trigonatus

Physical characteristics

In general appearance, alligators are similar to crocodiles, with stout bodies and powerful tails that are at least as long as their bodies. They have long snouts and noticeably toothed upper and lower jaws. Alligatorids are distinguished most notably from the crocodiles by their mandibular teeth, all of which slide inside the upper jaw and out of view when the mouth is closed. In contrast, the fourth mandibular teeth in crocodiles are visible outside the closed jaw.

Alligatorids are grayish, sometimes tending toward green, brown, yellow, or black, depending on the species. The young are often banded. Adult size ranges from about 4 ft (1.2 m) in Cuvier's dwarf caiman (P. palpebrosus) to 13 ft (4 m) in the American alligator (A. mississippiensis).

Like the crocodile's body, the alligatorid body is armored with tough osteoderms and, frequently, large scales that do not overlap. The osteoderms in some species do not extend onto the belly, making this smooth part of the skin highly desirable as leather for human uses. Alligatorids have short legs tipped with claws. The forelimbs are smaller than the hind limbs and have five, rather than four, partially webbed toes. Their body form allows them to glide in a sinuous pattern through the water, normally with just the side-to-side motion of the tail providing the locomotive force. On land the strength of their legs makes them quick and formidable predators.

Distribution

Primarily a New World group, all but the two Alligator species occur in southern Mexico, parts of Central America, or northern to central South America. Alligator mississippiensis is the only member of this family to be found in the United States, where it exists in southeastern states, from the Carolinas to Texas. A. sinensis makes its home in eastern China, far distant from its New World relatives.

Habitat

Alligatorids are restricted to freshwater areas and frequently are found in lakes, slow-moving streams and rivers, swamps, marshes, and other wetland habitats. Some species even make use of roadside ditches. They prefer sites with slow-moving or still waters. They often inhabit vegetated areas, sometimes with muddy or murky water.

Behavior

Alligatorids are ectotherms ("cold-blooded" animals) and most often are seen basking on the shoreline to raise their body temperature. Sometimes they are seen sliding along the shoreline on their bellies, using their feet to push them through the mud and muck to the water. They also do the "high walk," which is somewhat similar to a lizard's walk; alligatorids, however, hold their legs more upright than straddled. Although they may look sedate much of the time, their short legs can give them quick acceleration for grasping a passing mammal.

Careful observers also see them floating at the surface of the water, where only their most dorsal surface and occasionally just the nose and the tip of the head are exposed. Often, the animal actually is maintaining its internal temperature through this activity, either lying in the sun-heated upper layers of the water column to warm up or moving to shady, chillier waters to cool off. Their presence is made known when they begin to sweep their tails slowly and propel themselves gracefully forward. While they usually are motionless or swim slowly, they can make quick movements in the water. One noticeable trait is their ability to jettison almost vertically out of the water. This maneuver typically is accompanied by a quick chomp of the jaws around a startled bird or other prey item.

Alligatorids, including those in more temperate climates, do not hibernate. While temperatures in the southeastern United States and China can approach freezing in the winter, American and Chinese alligators remain active all year, though they are more subdued as temperatures dip and may even become dormant. To beat the cold, they move to shallow water and lie motionless, with just the nose poking into the cold air. Young alligators, on the other hand, may retreat to the mother's den to survive cold snaps. Juveniles and adults make use of burrows during winter months.

Alligatorids often live in groups and form dominance hierarchies, at least during the breeding season and sometimes all year. The highest-ranking individuals exert their dominance through various ritualized behaviors, which may include slaps of the head against the surface of the water, loud vocalizations, and open-mouthed charges.

Feeding ecology and diet

A typical juvenile diet includes snails and other invertebrates, whereas adults of various species commonly eat fish, small mammals, other reptiles (including smaller alligatorids), or birds. Opportunistic feeders, alligatorids continue to eat clams, snails, and invertebrates into adulthood. The larger species, including the black caiman, are known to take large prey, such as small deer and cattle.

Predation of alligatorids occurs primarily among eggs and hatchlings. Raccoons, coati, skunks, foxes, and other mammals, as well as snakes and various raptors, are known to raid nests or snatch up young alligatorids. Once an alligatorid reaches about 3 ft (1 m) in length, the risk of predation decreases. Nonetheless, anacondas in South America occasionally kill adult caimans, and alligatorids have been reported to have cannibalistic tendencies. Cannibalism is rare, however, and alligatorids frequently live peacefully in large groups.

Reproductive biology

Alligatorids begin the reproductive season in the spring. Following courtship, which may include loud bellows, tactile types of behavior, and underwater vibrations of the male's trunk, alligatorids use vegetation to construct nest mounds, where they lay from one dozen to five dozen eggs, depending on the species. Egg laying generally takes place once a year, in midsummer, with hatching one to two months later. Female alligatorids typically respond to sounds emanating from the neonate, dig up the nest, and assist in their hatching. Temperature-dependent sex determination has been associated with several species, including the American alligator and common caimans. Low nest temperatures (below 88°F, or 31°C) produce female hatchlings, and high temperatures (above 90°F, or 32°C) produce males.

Conservation status

The Chinese alligator is listed by the IUCN Red Book as Critically Endangered. This status stems primarily from loss of habitat due to human encroachment. According to the IUCN Crocodile Specialist Group, "The Chinese alligator is the most critically endangered crocodilian in the world. Thousands are bred in captivity, but fewer than 150 remain in the wild." The group is working with the Chinese government to protect the species and has launched the Chinese Alligator Fund to assist in these efforts. In addition, many conservation efforts over the past three decades have been implemented to prevent overharvesting of other alligatorids. The only other species listed by the IUCN is the black caiman, which is listed as Lower Risk/Conservation Dependent.

Significance to humans

Although the benefit is difficult to quantify, some species of alligatorids play an important role in the tourism industry. American alligators in the southeastern United States, for example, have become tourist attractions, drawing visitors to the Everglades of southern Florida and the bayous of Louisiana. Several members of this family are hunted, especially for their skin, which is used as leather for shoes, bags, and various accessories. Humans also hunt these animals for meat and, recently, for their gonads, which are used to make perfume.

Species accounts

American alligator
Chinese alligator
Common caiman
Smooth-fronted caiman

Resources

Books:

Alderton, D. Crocodiles and Alligators of the World. New York: Facts on File, 1991.

Ashton, Ray E., and Patricia Sawyer Ashton. Handbook of Reptiles and Amphibians of Florida. Part 2: Lizards, Turtles and Crocodilians. 2nd edition. Miami: Windward Publishing Co., 1991.

Behler, J. L., and D. A. Behler. Alligators and Crocodiles. Stillwater, MN: Voyager Press, 1998.

Campbell, G., and A. L. Winterbotham. Jaws Too: The Natural History of Crocodilians with Emphasis on Sanibel Island's Alligators. Ft. Myers, FL: Sutherland Publishing, 1985.

Guggisberg, C. A. W. Crocodiles: Their Natural History, Folklore, and Conservation. Harrisburg, PA: Stackpole Books, 1972.

Hirschhorn, Howard H. Crocodilians of Florida and the Tropical Americas. Miami: Phoenix Publishing Co., 1986.

King, F. Wayne, and Russell L. Burke, eds. Crocodilian, Tuatara and Turtle Species of the World: A Taxonomic and Geographic Reference. Washington, DC: Association of Systematics Collections, 1989.

McIlhenny, E. A. The Alligator's Life History. Boston: Christopher Publishing, 1935.

Minton, S. A., Jr., and M. R. Minton. Giant Reptiles. New York: Scribner, 1973.

Neill, W. T. The Last of the Ruling Reptiles. New York: Columbia University Press, 1971.

Ross, Charles A., ed. Crocodiles and Alligators. New York: Facts of File, Inc., 1989.

Zug, George R, Laurie J. Vitt, and Janalee P. Caldwell. Herpetology: An Introductory Biology of Amphibians and Reptiles. 2nd edition. San Diego: Academic Press, Inc., 2001.

Periodicals:

Brazaitis, P., M. Watanabe, and G. Amato. "The Caiman Trade." Scientific American 278 (March 1998): 70–76.

Stewart, D. "Visiting the Heart of Alligator Country." National Wildlife 38, no. 4 (June/July 2000): 20–27.

Thorbjarnarson, J. "The Hunt for Black Caiman." International Wildlife 29 no. 4 (July/August 1999): 12–19.

Thorbjarnarson, J., X. Wang, and L. He. "Reproductive Ecology of the Chinese Alligator (Alligator sinensis) and Implications for Conservation." Journal of Herpetology 35, no. 4 (December 2001): 553–558.

Zimmer, C. "Prepared for the Past." Natural History 110, no. 3 (April 2001): 28–29.

Organizations:

Crocodile Specialist Group, Florida Museum of Natural History. Box 117800, Gainesville, FL 32611-7800 USA. Phone: (352) 392-1721. Fax: (352) 392-9367. E-mail: prosscsg@flmnh.ufl.edu Web site:

Other:

Animal Diversity Web. [cited December 2002].

"Crocodilian Species List." 2002 [cited December 2002].

"Alligatoridae." The Reptipage. August 2002 [cited December 2002].

"Alligatoridae: Alligators, Caimans, and Their Prehistoric Relatives." December 1999 [cited December 2002].

"Crocodilian Biology Database." August 2002 [cited December 2002].

[Article by: Leslie Ann Mertz, PhD]

For more information on caiman, visit Britannica.com.

Crocodilian reptile of the family Alligatoridae, very similar to alligators; resident in Central and South America. Genus name is Caiman, e.g. C. sclerops the spectacled caiman.

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Dansk (Danish)
n. - [zool] kajman, alligator

Nederlands (Dutch)
kaaiman

Français (French)
n. - caïman

Deutsch (German)
n. - Kaiman

Ελληνική (Greek)
n. - (ζωολ.) (κροκόδειλος) καϊμάν

Italiano (Italian)
caimano

Português (Portuguese)
n. - caimão (m)

Русский (Russian)
кайман

Español (Spanish)
n. - caimán, cocodrilo

Svenska (Swedish)
n. - kajman

中文（简体）(Chinese (Simplified))
凯门鳄

中文（繁體）(Chinese (Traditional))
n. - 凱門鱷

한국어 (Korean)
n. - 중남미 산 큰 악어

日本語 (Japanese)
n. - カイマン

العربيه (Arabic)
‏(الاسم) نوع من التماسيح‏

עברית (Hebrew)
n. - ‮קאימן (תמסח)‬

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