As we've previously discussed, tarantulas, despite being pretty harmless, are still notoriously terrifying creatures. Even though they can bite humans, their bite isn't able to do much damage. Still, most people would be frightened to come across one in their everyday lives. Well, please allow me to make your natural fear of tarantulas even worse. There are some species of tarantulas that can hiss by rubbing together the bristles on their legs. Usually, this noise is a defense mechanism, so if you happen to keep a tarantula as a pet and it starts making this noise when you get close, you should probably just leave it alone. WARNING: This video is not suitable for arachnophobes. If that's not nightmare fuel, then I don't know what is. Just imagine that thing crawling all over your face while you're sleeping. Yeah...no thanks.