I found this charming fellow under a limestone rock in a Caribbean jungle. (As you do.) It's a whip scorpion (order Thelyphonida, also known as Uropygida). See that fine 'tail' sticking up like a car aerial from its rear? The whip scorpion uses it to spray enemies with acetic acid. A snootful of vinegar soon persuades a predator that this isn't a tasty meal. The claws at the front end had already sent that signal to me. The vinegar was just ... er ... icing on the cake.