Vinegaroons, relative of Scorpions that shoots vinegar, on my arm

Spider biologist gives me a hands on experience with one of her vinagrons. They are members of the Arachnid Class, and shoot acetic acid, or vinegar, out of their tail in order to protect themselves. They live in caves and in deserts all around the world. This one is Mastigoproctus giganteus, the giant whip scorpion, from North America.