puff adders

Puff adders are venomous African snakes that inflate their bodies and hiss loudly when threatened—the "puffing" that gives them their name.

They're responsible for more snakebite deaths in Africa than any other species, due to their wide range, excellent camouflage, and tendency to hold ground rather than flee.

The name also applies to the harmless North American hognose snake, which puffs up similarly as a bluff.