The Hairy angler (Caulophryne polynema) is a deep sea fish. The female is about the size of a football and its body is covered in long antennae, used to detect the movements of any prey nearby. The male is about a tenth her size - the size of a ping pong ball. He forms a parasitic relation with the female, attaching himself to her flesh, ultimately sharing in her blood circulation and becoming a dependable source of semen. It is thought that the extremely rare meeting of males and females would lead to such an arrangement. This fish was featured in the documentary series The Blue Planet.