Snakes have an organ in the throat called the glottis that they breathe through. Normally this is a quiet process, but by forcibly expelling air from the glottis, the telltale hissing sound emerges. Snakes hiss as a defensive tactic—one that is especially useful for small, non-venomous snakes.

What does it mean when a snake hiss at you?

Hissing is an intimidating sound, and it helps to dissuade would-be predators. A hissing snake can give the impression of a larger, more dangerous adversary. Additional defensive tactics snakes may use include biting, expelling musk, and simply fleeing.

Do snakes hiss when mad?

Even so, sometimes (but not always), boa constrictors and other snakes can and will hiss when annoyed, and let's face it, a hiss from a large snake will make anyone think before attacking! It's important to understand that snakes don't hiss in order to communicate with other snakes as they're not social reptiles.