Hognose Snake, a nonpoisonous snake of North America that is harmless to humans. It is also called the puff adder because it flattens its head and neck, inflates its body with air, and hisses loudly when disturbed. It rarely, if ever, bites in defense. If the intruder is not bluffed, the snake rolls over as if dead.

There are three species. All have upturned snouts, used in burrowing for toads, the chief food, although frogs and tadpoles are also eaten. Color varies greatly, out usually there are regularly spaced dark blotches along the upper sides and middle of the back.

The eastern hognose is Heterodon platyrhinos (usually 18 to 30 inches [45 to 75 cm]; color may be yellow, brown, gray, orange, or red, but jet black or nearly plain gray ones are known). The southern is H. simus (usually 14 to 20 inches [35 to 50 cm]; color fairly constant grayish brown). The western, which has several subspecies, is H. nasicus (usually 16 to 32 inches [40 to 80 cm]; belly must be checked to distinguish it from other species; usually has black ventral areas interspersed with white or yellow). All are of the family Colubridae.