pit viper, poisonous snake snake, common name for an elongated, limbless reptile of the order Squamata, which also includes the lizards. Most snakes live on the ground, but some are burrowers, arboreal, or aquatic; one group is exclusively marine. In temperate climates they hibernate.
..... Click the link for more information. of the family Crotalidae, primarily a New World family. Like the Old World true vipers viper, any of a large number of heavy-bodied, poisonous snakes of the family Viperidae, characterized by erectile, hypodermic fangs. The fangs are folded back against the roof of the mouth except when the snake strikes.
..... Click the link for more information. (family Viperidae), pit vipers have long, hollow, erectile fangs that are folded back against the roof of the mouth except when the snake is striking. In addition, the pit vipers have developed special organs of heat reception that help them to sense warm-blooded animals, an ability that is especially useful at night, when many of them hunt. These organs consist of pits, for which the group is named, located just behind the nostrils and covered with a temperature-sensitive membrane. Some pit vipers may also use these organs to find cool refuges from inhospitable daytime temperatures.

The largest group of pit vipers is the rattlesnake rattlesnake, poisonous New World snake of the pit viper family, distinguished by a rattle at the end of the tail. The head is triangular, being widened at the base. The rattle is a series of dried, hollow segments of skin, which, when shaken, make a whirring sound.
..... Click the link for more information. genus Crotalus, found in North, Central, and N South America. Other New World forms are the fer-de-lance fer-de-lance (fĕr'-də-lăns`), highly poisonous snake, Bothrops atrox,
..... Click the link for more information. (genus Bothrops) and the bushmaster bushmaster, large venomous snake, Lachesis muta, of Central America and N South America. It is a member of the pit viper family, which also includes the rattlesnake. The largest New World snake, it reaches a length of 8 to 12 ft (2.5–5.5 m).
..... Click the link for more information. (genus Lachesis). The genus Ancistrodon includes the copperhead copperhead, poisonous snake, Ancistrodon contortrix, of the E United States. Like its close relative, the water moccasin, the copperhead is a member of the pit viper family and detects its warm-blooded prey by means of a heat-sensitive organ behind the nostril.
..... Click the link for more information. and water moccasin water moccasin or cottonmouth, highly venomous snake , Ancistrodon piscivorus, of the swamps and bayous of the S United States. Like the closely related copperhead, it is a pit viper and has a heat-sensitive organ for detecting
..... Click the link for more information. , as well as about a dozen Asian species. Pit vipers are classified in the phylum Chordata Chordata (kôrdā`tə,–dä`–)
..... Click the link for more information. , subphylum Vertebrata, class Reptilia, family Crotalidae.

pit viper

Any species of viper (subfamily Crotalinae) that has, in addition to two movable fangs, a heat-sensitive pit organ between each eye and nostril which together help it accurately aim its strike at its warm-blooded prey. Pit vipers are found from deserts to rain forests, primarily in the New World. They may be terrestrial, arboreal, or aquatic. Some species lay eggs; others produce live young. See also bushmaster, copperhead, fer-de-lance, moccasin, rattlesnake.