Icthyoid Alien

Cymothoa exigua is a parasitic crustacean like no other, as it does not just live in its host but actually replaces part of it. First it attaches itself at the base of the tongue of the chosen fish, with the claws on its front three pairs of legs, and begins to extract blood. As the parasite grows, less and less blood is able to reach the tongue, and eventually the organ atrophies and dies, at which time the parasite attaches to the muscles of the tongue stub replacing the tongue with its own body. The fish is able to use the parasite as a fully functional tongue and the parasite survives on food particles, relieving the stress on the host’s appropriated circulatory system.