Really Weird Animals: Tongue-eating Lice

Tongue-eating and lice.  Those words by themselves do not bring pleasant thoughts.  This creature is a parasitic crustacean found off the coast of California and as far south as Ecuador, and has been sampled in water six to seven feet deep and down to 200 feet deep.

As juveniles, several tongue-eating lice will latch onto a fish and enter it through its gills.  The first crazy thing about these parasites is that they are “protandric hermaphrodites.”  Meaning: as the lice mature, they first become male (about 7.5-15 mm long).  Then usually one of them will turn into a female once it reaches 10 mm in length.  They can grow up to 29 mm in length

Tongue-eating louse (photo from the Wikimedia files) 

Females will crawl from the inside of the gills to the fish’s mouth and grab hold of the tongue.  They extract and consume the tongue’s blood through their front claws!  The tongue eventually dies and disintegrates from so much loss of blood and the louse becomes its new tongue, holding on to whatever nub is left.   So despite its name--the tongue-eating louse--it does not actually eat the tongue, but sucks its blood.  Although the process of losing its tongue is quite uncomfortable for the fish, the fish doesn’t die.  The parasite wants its host to live as long as possible, so it will then only occasionally consume its blood and mostly feed on the fish’s mucous.

Tongue-eating louse inside its host (photo from the Wikimedia files)

 Not much is known about this creature’s mating cycle.  They could possibly mate before the female ventures to become a fish’s tongue, or perhaps a male comes up to visit the female, or the female could just release her eggs in the direction of the males and they fertilize them.

Tongue-eating lice are not harmful to humans.  They are sometimes found in fish bought at supermarkets, but are usually dead along with the fish.

At the World Bird Sanctuary  you won’t find any tongue-eating lice, but we do have a healthy colony of Hissing Cockroaches.  When you visit be sure to check them out as they are very interesting.

Just as all creatures have a purpose in this world, even a tongue-eating louse can be food for other ocean dwelling life that finds these crustaceans floating around without a host!

Be sure to chew them well!

Submitted by Sara Oliver, World Bird Sanctuary Naturalist