Cymothoa exigua, also commonly known as the tongue-eating louse, is a parasitic isopod of the family Cymothoidae. As an ectoparasite, it lives on the outside of the host, and is found throughout the Atlantic and Pacific Oceans. Adults grow up to an inch in length and are among the largest isopods recorded. C. exigua are hermaphrodites, and are all born as a male before switching to female later in life. As such, female C. exigua are generally larger than males.