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Cymothoa Exigua Parasite Found in Britain.

Updated on January 5, 2012

Amazing photo from

"Hey, bro, what's goin' on!? Tongue fully replaced by parasite in this picture.
"Hey, bro, what's goin' on!? Tongue fully replaced by parasite in this picture.

Check inside fish's mouths!

One of the world’s most amazing parasites was found inside a fish for sale in the UK, and quite a few reports of more finds by fishermen have come in over the last few years off our coasts.

This, as named in the title, a crustacean, of the order Isopodia, is the same family as the woodlouse and resembles this creature, familiar to all British folk.

If you found one of these in the nice Snapper you were preparing for the oven or frying-pan, you would be in for a nasty shock!

The female parasite enters through the fish’s gills and attaches itself to the base of the host’s tongue, (the male can also be present, behind the larger female, attached to the unfortunate fish’s gill arches).

I say “unfortunate,” because the female digs-in a series of spiked, hooked legs into the victim’s tongue and begins to suck all the blood out!

Soon, the tongue “dies” and atrophies, but the fish is not doomed. This is because the clever Cymothoa now acts as the host’s tongue! The fish uses the parasite as its tongue for mechanical maneuvers, with little apparent detriment to itself, while the invader continues to find nutrients from the blood and other fluids of the mouth area. I don’t have any information as to how long this symbiotic (of a sort) relationship continues, perhaps until the fish or parasite dies of old age!

This is THE ONLY example we know of in the whole natural world where a parasite fully replaces a complete organ of its host! Must be handy having a tongue which can see what you are about to eat. “Watch out, stoopid, that worm has a hook in it!”

The creatures have been found in several fish species, but seem to especially target Snappers. They are mainly found in warmer locales, especially the Americas: the specimen coming to light in Europe, much to the dismay of the customer, as they are ugly little critters, may have been in an imported fish.

In the unlikely event your Friday fish dinner does include one of these chaps, don’t pick it up as they will run up your arm and try to get a grip on your tongue!! No, not really, just seeing if you were paying attention. But they can bite quite viciously with the powerful frontal mandible legs.

Not large, the female can be just over and inch or so and about a half-inch wide…the male is appreciably smaller.

Despite people claiming to having been poisoned by cooking and eating a fish containing a parasite, this has been proven untrue and the parasite is not poisonous in itself and probably edible.


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    • TIMETRAVELER2 profile image

      Sondra Rochelle 5 years ago from USA

      I think I just lost my taste for fish. This was disgusting, but oddly interesting. Well done.

    • Au fait profile image

      C E Clark 5 years ago from North Texas

      Sounds yummy! You should have included a recipe. Once it's cooked feasters could draw straws to see who gets it! A delicacy for sure.

      Interesting hub as always. Hope you are well, Bobby. Haven't seen or heard anything of you in ages. Hope you're still breathing . . .

      Voted up and interesting. Will share.

    • GlstngRosePetals profile image

      GlstngRosePetals 5 years ago from Wouldn't You Like To Know

      Wow This is like the movie alien when the thing in the mouth sticks its nasty head out. Great article Voted up !!!

    • profile image

      diogenes 6 years ago

      It is gross. But what an amazing creature to be able to take the place of the tongue! Utterly amazing...Bob

    • WillStarr profile image

      WillStarr 6 years ago from Phoenix, Arizona


      I can't say I wasn't warned!

    • Sherry Hewins profile image

      Sherry Hewins 6 years ago from Sierra Foothills, CA

      Eeew that's really gross.

    • moonlake profile image

      moonlake 6 years ago from America

      There's a good video on YouTube of this awful looking parasite. I think it was found in a fish in Texas.

      Good hub interesting.

    • profile image

      diogenes 6 years ago

      Hi Sunnie: I don't know whether you have read all or any of my other creepy-cralie hubs, I have written lots. Thanks for visit...Bob

      Yes, quite ancient writings mention them

    • profile image

      Sunnie Day 6 years ago

      Good Morning Bob,

      This was quite fascinating. I do love to fish! I can't imagine reaching in to get the hook out and find one of these little critters staring at me. From the picture they do not look too tiny. I bet they have been around along time but just have evolved to different forms..what do you think? I was paying attention as far as running up my arm and gripping my tongue..haha

      Good article..I find things like this very interesting..

      Thank you..and have a great day,