One glimpse of a full-grown gorilla, and you know why no other animal in the wild messes with him.

We're talking 400 pounds of pure muscle and the strength of maybe eight Arnold Schwarzeneggers plus humongous teeth that chomp tree bark like Cheetos and an arm span longer than Michael Jordan.

If the male gorilla leader (or silverback) thinks you're a threat, he'll stand up on his legs, slap his chest, roar and even charge. (The silverback gets his name from his back hair, which turns silver with age.)

But here's the word from Jennifer Chatfield, gorilla keeper of the Los Angeles Zoo: Gorillas are mostly bluff. They'd much rather scare intruders away than hurt them (and that usually works!)

Michael hooting and chest slapping, full version (AIFF format, 230k)

Michael hooting and chest slapping, smaller version (AIFF format, 42k)