Friday, January 28, 2011

Invasion of the Tongue Snatcher, Cymothoa exigua


[1]

Introduction to Cymothoa exigua:
The world of parasites can only be described as interesting. One parasite that enhances this claim is the Cymothoa exigua. This parasite seems to have a parasitic relationship with its hosts the Spotted Rose Snapper, Lutjanus guttatus, and the Red Snapper, Lutjanus peru. The Spotted Rose Snapper is found in all Mexican coastal fishing waters on the Pacific coast south to Guatemala, with the exception of the Pacific Side of the Baja California Sur peninsula and the oceanic islands [2].

Cymothoa exigua:
Cymothoa exigua is part of the family Cymothoidae in the order Isopoda which are known to target fish as their host. It usually found in the gills or the mouth of the snappers. If it the parasite is a male, it stays in the gills. If it is female it enters the fish through the gills and makes its way into the mouth and attaches to the tongue. Once attached to the tongue, it feeds on the blood until the tongue atrophies. This is when it gets interesting. Once the tongue is gone the parasite attaches to the stub of the tongue and then acts as the tongue and steals some food that the fish eats. The males can grow to a length of 8 to 19 mm while the females can grow to 21 to 37 mm [3].
[2]

Lutjanus guttatus and Lutjanus peru:
These fish belong to the Lutjanidae family, otherwise known as the Snappers, in the order Perciformes. These fish usually grow 15-18 inches long but have been found at two and a half feet and is found around 250 feet below the surface over sandy bottoms and not around rocky reefs [2].

Life Cycle of Cymothoa exigua:
Not much is known about the life cycle of this parasite. What is known is the parasite enters through the gills of the snapper. The parasite also sexually reproduces. If there is no female inside the fish and there are 2 males, one of the males can turn into a female after it grows to 10 mm [3]. How the parasite’s eggs are released is not known. Data analyses and reviewed literature allow proposing the hypothesis that the snapper is infested early in its life cycle by severa1 isopods at once with successful implantation of some of these. The life cycle of the isopods could be completed in the host and after a female of C. exigua finishes her cycle and dies, it may be replaced by a male breaking this sequence when no other male is available [3].

Ecology:
The parasite does not cause much harm to the host. The females only replace the tongue. The only damage that is caused is by male C. exigua. “Additional reports about the damage caused by male parasites include hematophagy (Morton, 1974; Brusca, 1981) and excessive mucus secretion on gill chamber surfaces which eventually affect the respiratory process” [3]. It has not been shown to affect the growth of the fish however so the harm caused to the host is minimal.

An example of the diversity of parasites. Sure many parasites feed on the blood of their host, but how many feed on the blood of a host until the organ atrophies and then functions as the organ itself? Only one. This is the only known parasite to replace an organ that it atrophies.

And now a video for your enjoyment! Don't worry though this parasite does not attack humans and the reason this fish was found in New Jersey and other places is because it was imported in.

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Craziest F#?king Thing I've Ever Heard - Tongue-Eating Parasite
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References:
[1] http://blogs.discovery.com/.a/6a00d8341bf67c53ef0120a738a902970b-800wi
[2] http://www.mexfish.com/fish/sptrssnap/sptrssnap.htm
[3] http://www.cienciasmarinas.com/index.php/cmarinas/article/view/885/807
[4] http://blogs.discovermagazine.com/loom/2009/12/08/lets-haunt-their-dreams-forever/

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