I doesn’t eat your tongue, it cuts off the blood supply so it dies and falls out, then the creature can take its place.
Doesn’t that make it seem better? 
Great fleas have little fleas
Upon their backs to bite 'em,
And little fleas have lesser fleas,
And so ad infinitum.
–* attributed to Ogden Nash and others*
In the world of [del]the blind[/del] Captain Hook, [del]the one-eyed man[/del] John Carpenter’s the Thing and the Human Centipede is king.
It’s gross, but the fish doesn’t seem bothered (they drink their own pee!) and AFAIK it doesn’t hurt their ability to eat. In the animal kingdom, where Alien chestbursters are a reality, it’s not so bad. Relatively speaking.