Cymothoa exigua

Cymothoa exigua

Cymothoa exigua is a parasitic isopod of the family Cymothoidae. This parasite enters fish through the gills. The female attaches to the tongue and the male attaches on the gill arches. Using its front claws, C.  exigua severs the blood vessels in the fish’s tongue. This causes the tongue to atrophy from lack of blood.

About Cymothoa exigua in brief

Summary Cymothoa exiguaCymothoa exigua is a parasitic isopod of the family Cymothoidae. This parasite enters fish through the gills. The female attaches to the tongue and the male attaches on the gill arches. Using its front claws, C.  exigua severs the blood vessels in the fish’s tongue. This causes the tongue to atrophy from lack of blood. The parasite then replaces the fish’s tongue by attaching its own body to the muscles of the tongue stub.

This is the only known case of a parasite assumed to be functionally replacing a host organ. It is not known what then happens to the parasite in the wild. It can be found from Gulf of California southward to north of the Gulf of Guayaquil, Ecuador. New hosts from Costa Rica include the Colorado snapper, Lutjanus colorado and Jordan’s snapper.