Crotalus sp.—Rattlesnakes // Crotalus atrox—Western Diamondback Rattlesnake // Crotalus molossus—Black-tailed Rattlesnake // Crotalus molossus—Black-tailed Rattlesnake // Crotalus oreganus—Western Rattlesnake //Crotalus viridis—Prairie Rattlesnake
The pitvipers include the rattlesnakes, Copperhead, and Cottonmouth. The name of the family refers to its members having a pit (Fig. 1) on the side of the head that detects infrared radiation, and thus is able to accurately locate the position of warm-blooded prey in the dark.
The Copperhead and Cottonmouth occur only east of our region. However, the region hosts a large number of species of rattlesnake, all of which are placed in the genus Crotalus except for the Massasauga (Sistrurus catenatus). Although crotalid vertebrae are distinctive from those of other snakes of our region, few if any species are identifiable with certainty on the basis of vertebrae. Although there are differences in adult size among the species, this seldom is conclusive in identification.
Fig. 1. Black-tailed Rattlesnake showing the position of the pit (within the red rectangle). The nostril is separate and located just above the rectangle toward the right. Photograph by A. H. Harris.
All members of the family are venomous with a sophisticated injection system. The fangs, located at the front of the mouth, normally are folded back, but become erect when the mouth opens for a strike. The fangs are hollow, with the cavity being connected with the poison glands; an opening toward the distal, anterior portion of a fang allows injection of the venom. The venom is primarily for the acquisition of prey, but of course also is utilized as a defensive weapon.
Last Update: 5 Dec 2013