Photograph of Aruba Island Rattlesnake, Crotalus Unicolor

-- The Aruba Island rattlesnake belongs to the family of vipers, Viperidae. Pit vipers together form the subfamily Crotalinae. The pit vipersa are so-called because they have heat-sensing pits behind and below their nares nostrils . Besides rattlesnakes, some other kinds of pit vipers are water moccasins also known as cottonmouths , copperheads, palm vipers and bushmasters.