Isopod got your tongue ?

It's a bizarre creature that survives by eating its hosts' tongue and then attaching itself inside the mouth.

The sea-dwelling parasite attacks fish, burrows into it, and then devours its tongue. After eating the tongue, the parasite proceeds to live inside the fish's mouth. There's a horror film waiting to be made about this thing. Surprisingly, the fish doesn't seem to suffer any severe impediment--just the loss of its tongue--and seems to have no trouble surviving with its new, far uglier tongue.

* This weird isopod creeps in through the fish’s gills and attaches itself to the base of the tongue.

* The parasite sucks blood from the tongue, and the tongue slowly withers away (it does not really ‘eat’ the tongue).

* When only the muscular stump of the tongue is left the parasite attaches itself and from then on behaves like a normal tongue. (This article gives more details.)

* Once attached and behaving like a normal tongue (it is about the same size and shape as the fish’s tongue was) the parasite will have cut off the blood supply it formerly fed on, so it begins to eat scraps of food that enter the fish’s mouth.

* The fish does not seem to be unhealthy, and it continues to behave normally and grow. Only looking in the mouth reveals the bizarre ‘passenger’.