Found in the deserts of Northern Africa and the Middle East, horned vipers are small, usually under 50 cms long. They often have a pair of horns over the eyes, but there are also some individuals that lack them completely, and, therefore, can be easily mistaken for other vipers. They are venomous, but their bite is usually non fatal to humans. When threatened they rub their coils together to produce a warning sound before they strike. The horned viper was formally named "Cerastes cerastes" in 1768, by Austrian naturalist Nicolaus Laurenti. Cerastes was a mythical Greek monster, a serpent that hid under the sand in the desert and ambushed any passing creature, using its horns as a lure.