jumping vipers grow up to the length of around 90 centimeters (36 inches), while the longest ever found was 120.2 centimeters (47 in). all of them are thick-bodied, with the mexican jumping pit viper being the thickest, and the picado's jumping pit viper being the slimmest. it has a large head, with small eyes, and a rounded snout, it also has a short tail. they are gray-brown, reddish brown or black in color with brown blotches on them.