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Wednesday, January 28, 2009

This Week's Sci-Fi Worthy Parasite

What could be more sci-fi than a case of replacing body parts? Sure, we might figure to do it with machines or cloning instead of another species, but fish don't get that luxury. Snappers have a wonderful parasite that works with them, to a point, to replace a part of their bodies.

Of course, the parasite - a crustacean (Cymothoa exigua) - first causes the part it's replacing to die - so it's not exactly a voluntary procedure. And what part does this lovely parasite replace?

Cymothoa exiguaThe tongue.

Cymothoa exigua enters the fish's mouth through the gills and latches on to the base of the tongue. From there, it feeds on the blood supply. As the blood is taken in by the parasite instead of the tongue, the muscle eventually atrophies and dies. The loss of a tongue could be a huge detriment to the fish, making it much less fit, unable to handle its food properly, and possibly even die. Cymothoa extinguaOf course, a dead host is no good to a fully-grown parasite, as it means a the food stops coming. So Cymothoa has evolved a truly amazing behavior: it acts like the fish's tongue. The fish can control the parasite just like it would its own organ, and thus the crustacean can live and feed off of its host's blood and mucus as long as it lives.

It seems like a nice gesture by the parasite, replacing a lost organ and all. That is, until you think about the fact that the old tongue was totally fine to begin with...

We might use the phrase "cat got your tongue?" when talking to other people, but if we're talking to a fish, " Cymothoa got your tongue?" might be more appropriate.

7 comments:

liliannattel said...

Interesting and at the same time gross. I can't help feeling my own tongue while reading this.

Christopher said...

This reminds me of a very similar case described by Lewis Thomas in the title essay from his book The Medusa And The Snail. I remember it was a case of a small jellyfish moving into the mouth of a snail, with its tentacles eventually falling off so that it becomes totally dependent on the snail's intake, feeding off of it. Of course I also can't help thinking of The Thing and a creature in the book Interstellar Pig. Which makes me wonder if there's anything imagined in science fiction that doesn't already exist somewhere on Earth.

Bjørn Østman said...

The fish controls its new tongue by using the usual muscles, or what?

Christie Lynn said...

Bjørn: Honestly, I can't seem to find any study or article that says how, per se. It seems to be simply said to be true. I would be very interested to find out such a thing myself...

James Hale said...

Definitely in my top 3 parasites. Is anyone else worried how sweet its face looks?

southernfriedscientist said...

That isopod has a fish growing out of it...

Karen James said...

This is so excellent. I've already shared the story with several unsuspecting family members to great effect.