The Secret Life of a Tongue Eating Louse

By Li Ken Lau, 2019 Alumni

Picture this: you have been tasked— by a rather oddball producer for some obscure late-night TV show— to interview a fish. You’ve seated that polite, aquatic gent in the studio. You then ask that question we’ve all (don’t deny it!) been burning to ask for decades: have you ever seen Nessie?

Silence fills the room as Fish opens its mouth to reveal, to our shock and horror, a miniature monstrosity! It’s a parasite!

Hello! I’m here for the interview!

Image by idalingi, via Visual Hunt

While this questionable scenario is certainly an unabashed work of fiction, the parasite Cymothoa excisa (the tongue eating louse to its friends), is very much real. They would also have a great tale to tell: with a lifecycle coloured in subterfuge, romance, and a dose of tragedy. What more could you want from the late-night tele?

Enter the saboteur

A member of the Cymothoidae family, which has nearly 400 species of fish parasites, C. excisa begins his life in a fish’s mouth alongside a family of all male siblings. Let’s call him Ted. After growing up a little, Ted’s parents bid him farewell and sends the entire brood out into the Deep Blue. There certainly isn’t enough room to go around!

Ted’s next move is to shoot towards the closest fish in the vicinity. He prefers the humble Atlantic croaker, though connoisseurs in his extended family may prefer other fishes. His parents were kind enough to drop Ted nearby a school of croakers, and the parasite soon hitches a ride.

For its next trick, our vampiric friend crawls with grim determination into the fish’s gills, where it feeds off the fish’s blood. Ted grows up healthy, strong, and also turns himself into a lady! C. excisa, like many of its cousins, are ‘hermaphrodites’; they have the ability to transform into members of the opposite sex. In particular, Ted’s (or shall we call her Lady Ted?) family are ‘protandrous hermaphrodites’ whom are all born as men, but can transform into ladies if necessary. This change paves the way towards any young chap/lass’ dream: moving into a larger commode.

A one room flat that comes with a full larder? What a steal!

Image by Undy Bumgrope, via Visual Hunt

Let’s settle in… forever!

Alone in the croaker, Lady Ted makes her move: to the more luxurious mouth district. Our protagonist, the tongue eating louse, now fulfils its manifest destiny and begins extracting blood from the fish’s tongue, while anchoring itself to the fish permanently with its hind legs. All this is well and good until the tongue shrivels under its unfavourable conditions and falls off.

This is where Lady Ted comes in. Our parasite will now, for all intents and purposes, behave like the fish’s tongue! The only known organism on the planet to replace the organ of another creature, this parasite will forever be part of the fish, whom doesn’t really have a say in the matter (non-withstanding its present deficit in the tongue department).

A home all but secured, Lady Ted spies a charming new gent entering the fray, and things get rather heated.

Romance… and looming tragedy!

It’s love at first sight! Lady Ted is struck speechless at this magnificent specimen of bug, whom is likewise entranced. One thing leads to another, and they are now happily wed, all in the mouth of the fish. Dad goes to make a living in the fish’s gill, while Lady Ted begins a pleasant home life raising her two to three hundred children, before bidding her sons farewell and sending the entire brood out into the Deep Blue. There certainly isn’t enough room to go around!

What happens next is up for debate. Some speculate that Lady Ted can make a decent living off eating the mucus and morsels that the fish picks up. Others suggest that once the croaker’s tongue falls off, Lady Ted loses her source of food altogether. This means that she’ll inevitably starve.

And starve she does! This is where Lady Ted meets her unfortunate end. And the fish, whom you may recall houses all this drama, is now left without a tongue. By now malnourished and anaemic, this is the final straw and our poor friend the Atlantic croaker croaks.

Long story short, the parasite starves and dies, the fish housing it starves and dies, and all of Lady Ted’s suitors still hanging around will starve and, unsurprisingly, die. But don’t despair! The story will live on. The many Ted Juniors are, after all, heading off towards another Atlantic croaker…