Wagler's Pit Viper

A viper of the subfamily Crotalinae (142 species), sometimes treated as a separate family absent from Africa. Front of face with small heat-sensitive pit on each side; can hunt and attack in total darkness by sensing prey's body heat. pit viper, poisonous snake of the family Crotalidae, primarily a New World family. Like the Old World true vipers 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.