The Crotalinae , or crotalines, are a subfamily of venomous vipers found in Asia and the Americas . They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on either side of the head. よりたくさんの

The Crotalinae , or crotalines, are a subfamily of venomous vipers found in Asia and the Americas . They are distinguished by the presence of a heat-sensing pit organ located between the eye and the nostril on either side of the head. Currently, 18 genera and 151 species are recognized: [ 4 ] 7 genera and 54 species in the Old World , against a greater diversity of 11 genera and 97 species in the New World . These are also the only viperids found in the Americas. The groups of snakes represented here include rattlesnakes , lanceheads and Asian pitvipers . The type genus for this subfamily is Crotalus , of which the type species is the timber rattlesnake, C. horridus . less