This crustacean invades a fish's mouth, devours its tongue, and takes the tongue's place. It then acts like a tongue; the fish can use it to grip and swallow prey. -- I officially never want to be a fish!
Cymothoa exigua (or the tongue-eating louse) is a parasitic crustacean of the family Cymothoidae. This parasite enters fish through the gills, and then attaches itself at the base of the fish's tongue.
Barnacles are not the only parasites which infest these animals, for the humpbacks, and in fact almost all the large whales, bear numbers of crab-like crustaceans (Cyamus), about half and inch in length, called “whale lice.” On the right whales these “lice” produce an irritation upon the top of the snout that a large, irregular roughened patch, called the “bonnet,” is formed: on the side of the lip and over the eyes are other and smaller patches infested with the troublesome crustaceans.
This extraordinary image, captured by Japanese scientists, marks the first-ever record of a live giant squid in the wild. The mysterious deep-sea creature has inspired countless sea monster tales and a variety of scientific expeditions.