Tongue-eating Louse

Cymothoa exigua, commonly known as the tongue-eating louse, is a parasitic isopod of the family Cymothoidae found throughout the Atlantic and Pacific Oceans. As an ectoparasite it lives on the outside of its host, and adults grow up to an inch in length, among the largest isopods recorded. All individuals are born male before switching to female later in life, a form of hermaphroditism that generally leaves females larger than males.