12 Unnecessarily Nightmarish Creatures That Scuttled Straight Out Of Hell
4. The "Just Plain Rude" Tongue-Eating Louse
From the very big to the very small (and the no less horrifying), welcome to the world of Cymothoa exigua, or the tongue-eating louse.
A relative of the giant isopod, these little guys have decided that the bottom-feeder life just isn't for them, and have developed a slightly more, er, invasive technique for acquiring nutrients.
The louse will enter the fish's system via the gills and will then set up home in its mouth. It does this by severing the blood vessels that feed the host's tongue, causing it to die and eventually fall off. It will then latch onto the stub and replace the tongue.
From there on in it can simply snap up a portion of whatever the fish eats without putting any of the legwork (or should that be finwork?) in. If the fish decides to go on a bit of a diet then, not to worry, because the louse will simply feed on its host's blood and mucus until the food starts rolling in again.
The female is generally the one that latches onto the tongue, whereas the male will hitch a ride in the gills. By all accounts, the fish won't even notice that it has an unwelcome lodger, and will carry on with its life as though it doesn't have a hellish hitchhiker making itself at home in its head.