You may NEVER want this 'Tongue' - Cymothoa exigua

At the first sight, many people may find this little parasite adorable (or is just me?). In the above image, Cymothoa exigua (yes, this is the creature's scientific name), looked exactly harmless, so tiny and cowardly hiding in the mouth of a fish.

However, in the view point of the host, this is totally NOT a pleasant experience. So, what harm can the little creature inflicts?

Guess it?

Cymothoa exigua is the first known parasite that replaces hosts' body parts upon parasiting. In this case, is the poor fish's tongue.

This little creature enters a fish mouth through the gills. Discovers its way to the tougue and attaches itself to the base of the tongue. After that, it happily sucks blood from the veins on the tongue using claws on its 3 pairs of legs at the front.

A fully grown Cymothoa exigua can be up to 3 to 4cm in length. Imagine the amount of blood it will need (also think of the size of the tongue of the fish). Eventually, the tongue withers due to lack of supply of blood and shrink till it loses its original function.

Cymothoa exigua is not that cruel to let the fish carry on its life without a tongue. As a result, the little parasite replaces itself as the tongue of the fish by attaching to the muscles of the tongue stub. Interestingly, the fish can freely use its "new tongue" at its control.

In the mean while, Cymothoa exigua survives by either the blood of the fish or the mucus of the fish. Other than having a whole new tongue, the creature does not inflict any other damage to the host fish. An extra tongue, anyone?