If you see a freaky looking creature staring out at you from inside a fish’s mouth the next time you catch a fish, say hello to Cymothoa exigua. In this instance the parasite crawling out from the fish’s mouth happens to be a kerisi (threadfin bream). These freaky looking parasite are not that uncommon.
The Cymothoa exigua parasite, a type of crustacean, swims into the fish’s mouth and attaches itself at the base of the poor fish’s tongue. It leeches blood from its victim and as it grows, the tongue withers and dies due to lack of blood supply. Eventually when the tongue dies completely, either diminishing or falling off, the parasite then switches places with the stump and acts as a working replacement for the organ, allowing the fish to use it just like a normal tongue.
The parasite spends the rest of its life living off both the fish’s blood and bits of food that enter the fish’s mouth. The Cymothoa exigua is the only parasite known to effectively replace a body organ.
Do you enjoy eating fish? Bon appetit!