Tongue-Eating Parasite Makes News Again

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Do you remember the tongue-eating parasite? If not, here's a visual reminder:

(Credit: Matthew Gilligan)

I told you about this photogenic species, Cymothoa exigua, at Animal Planet back in 2005. The parasite is making news again this week, at Treehugger, Colbert Nation, the BBC and other media outlets. According to the reports, fishermen near the Minquiers— a group of islands off the coast of Normandy, France— spotted the parasite inside a weaver fish.

As you can see from the above photo, this 1-inch isopod targets the tongue, eating away at it until finally the parasite itself becomes the tongue. Lucky for us, it only attacks fish tongues, although people who find them outside of fish claim they deliver a painful bite. 

(Image: Horniman Museum)

Paul Chambers, from the Société Jersiaise and one of the Minquiers fishermen, told the BBC that the parasites "are quite vicious" and "they will deliver a good nip" to people who dare to pick them up, as he did.

Chambers said he and others in his fishing party found the parasite when they emptied a bag of fish and "out there at the bottom was this incredibly ugly looking isopod."

"Really

quite large, really quite hideous," he added. "If you turn it over, it's got dozens

of these really sharp, nasty claws underneath and I thought 'that's a

bit of a nasty beast.'"

Matthew Gilligan, professor of marine sciences at Savannah State

University in Georgia, told me he believes the

tongue-eating species is much more widely distributed than most people suspect.

(A London cook almost prepared this fish before finding the parasite; Credit: Matthew Gilligan)

As an isopod crustacean, the parasite is shell-covered, leggy and segmented. Other more common isopods include

sowbugs and pillbugs. The group dates back at least to the

Carboniferous Period of the Paleozoic, approximately 300 million years

ago.

While tongue eating and replacing is unique to this particular species, Gilligan thinks the behavior probably evolved out of trial and error.

"They (parasites) are always testing the envelope on what they can get

away with," he said. "Killing the host is self-destructive —

maladaptive in evolutionary terms — but it is remarkable how much host

damage can be inflicted by parasites while not severely impacting

survivorship of the host."

Although fish obviously need their tongues, "an isopod tongue is more useful than no tongue at all,"

Gilligan deadpanned.

Other experts have even told me that the parasite will manipulate food as the host eats, just as the real tongue would, with one major catch. The louse eats some of the meal, dining out for free while in the warm, protective confines of its victim's mouth.