The Cymothoa exigua or the Tongue eating louse is a parasitic crustacean of the family Cymothoidae

The Cymothoa exigua or the Tongue eating louse is a parasitic crustacean of the family Cymothoidae(Isopods). It tends to be 3 to 4 cm long. This parasite enters through the gills, and then attaches itself at the base of the spotted rose snapper's tongue. It then proceeds to extract blood through the claws on its front three pairs of legs. As the parasite grows, less and less blood reaches the tongue, and eventually the organ atrophies from lack of blood. The parasite then replaces the fish's tongue by attaching its own body to the muscles of the tongue stub.Image by Dr.Nico Smit.Read more about it on MFS.