What is a viper?

   A viper is a poisonous snake belonging to the Viperidae family. The family is divided into pit vipers and true vipers. Pit vipers, found mainly in America, have a deep pit between the eye and nostril. The true vipers or adders lack the pit; they are found in South America, Africa, Asia, India, and Great Britain. The true vipers are heavy, slow snakes, usually terrestrial and protectively colored in grey, brown, and black. The heads are flat and the poison fangs are attached to the upper movable jaws. When not in use, the fangs fold back in the mouth. The fangs are like long hollow teeth which are able to inject venom into a wound because of their connection with the two poison glands. If the fangs become broken, reserve fangs move down into place. The majority of the vipers do not lay eggs but bring forth living young.