Cymothoa exigua

Cymothoa exigua
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Malacostraca
Order:	Isopoda
Family:	Cymothoidae
Genus:	Cymothoa
Species:	C. exigua
Binomial name
Cymothoa exigua (Schiødte & Meinert, 1884)

Cymothoa exigua, or the tongue-eating louse, is a parasitic isopod of the family Cymothoidae. It enters fish through the gills. The female attaches to the tongue, while the male attaches to the gill arches beneath and behind the female. Females are 8–29 mm (0.3–1.1 in) long and 4–14 mm (0.16–0.55 in) wide. Males are about 7.5–15 mm (0.3–0.6 in) long and 3–7 mm (0.12–0.28 in) wide.^[1] The parasite severs the blood vessels in the fish's tongue, causing the tongue to fall off. It then attaches itself to the remaining stub of tongue and the parasite itself effectively serves as the fish's new "tongue".^[2]

Many species of Cymothoa have been identified,^[3] and only cymothoid isopods are known to consume and replace the host's organs. Other species of isopods known to parasitize fish in this way include C. borbonica^[4] and Ceratothoa imbricata.^[5] Different cymothoid genera are adapted to specific areas of attachment on the host. This includes scale-clingers, mouth- or gill-dwellers, and flesh-burrowers.^[6]