Viperidae

About the Viperidae family

Vipers are ambush predators with the most sophisticated venom-delivery system of any snake: long fangs that fold back against the roof of the mouth and swing forward to stab. The family splits into true vipers (adders, Gaboon viper, Russell's viper, saw-scaled vipers) and pit vipers (rattlesnakes, copperheads, cottonmouths, lanceheads, bushmasters), which have a heat-sensing pit between the eye and nostril.

Where they live

Worldwide except Australia, Antarctica, and most oceanic islands. Pit vipers dominate the Americas and Asia; true vipers, Africa and Eurasia.

How to recognize one

Broad, triangular head distinct from a narrow neck, heavy body, and (usually) vertical, cat-like pupils. Pit vipers also have a heat-sensing pit; true vipers do not.

Danger to people

Every viper is venomous, and the family includes some of the world's most medically important snakes. Venom is typically hemotoxic, causing pain, swelling, tissue damage, and bleeding. Treat any viper bite as a medical emergency.