Cymothoa Exigua and Creationism

The Evolution Facebook page shared the interesting example of parasite behavior I am quoting in full below. The photo may give you nightmares. The question I want to ask is what young-earth creationists and others who reject evolution say about such organisms. Do they envisage God creating these parasites specifically to do the things that they do? And if so, why? I expect that I am not alone in finding evolution to give not merely the best scientific explanation, but also an account that is theologically preferable to one that envisages God creating creatures directly to survive and reproduce in these specific ways. Read the information below, and then please share your thoughts on this!

Cat got your tongue, or is it Cymothoa exigua?

Parasites often alter their host's behaviour or appearance, but Cymothoa exigua goes one further – it is the only parasite known to replace an entire organ. Its unfortunate host is typically the rose spotted snapper, which it enters through the gills and lodges itself at the back of the mouth. It hooks its claws at the base of the tongue and interrupts the blood flow, consuming it instead. Due to the lack of blood the tongue atrophies and falls off, whereupon the isopod parasite attaches itself to the remaining stub. It then “becomes” a functional tongue for the fish, able to be moved as the fish would have moved its original tongue.

Like most cymothoid isopods, C. exigua is a hermaphrodite. In one study females were only found in the mouth, whereas males could be found in the gills and the mouth (and in the mouth they were clinging to females, suggesting copulation). A small proportion of extremely un

lucky fish were found with females as the tongue and males simultaneously occupying the gills. Despite the “organ-replacement” part, it doesn't appear C. exigua has other adverse effects on the fish.
In case you were wondering (and we're sure it crossed your mind at some point), C. exigua does not affect humans. That said, don't pick one up – they deliver quite a nip.
Photo credit: Dr. Nico Smit.


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  • Gary

    “In case you were wondering (and we’re sure it crossed your mind at some point), C. exigua does not affect humans.”…Maybe until the red snapper population is depleted. Then another host? I will pass on sushi for awhile. He just has to adapt to alittle lower into the throat, away from prying fingers. But might help the diet, if he just shares.

  • Susan Burns

    Cool! Biologic adaptations never cease to amaze me. Parasites can be also be mutually beneficial to host and organism. Humans could not survive without the bacteria parasites that live in our gut. Mitrocondrial organelles may have started their evolutionary process separately and then forming symbiotic relationships with their host creating an entirely new functional process.
    Evolution seems to sacrifice many organisms to bacterial infestations to find that one individual that can use the parasite beneficially. That individual then passes this newly found ability to its offspring resulting in a more robust gene pool. The Black Death that ravaged Europe has resulted in whites being more immune to the AIDS virus than blacks.
    “By the toll of a billion deaths man has bought his birthright of the earth, and it is his against all comers; it would still be his were the Martians ten times as mighty as they are. For neither do men live nor die in vain.” – H.G. Wells

  • Kaz

    “I expect that I am not alone in finding evolution to give…[snip] an account that is theologically preferable to one that envisages God creating creatures directly to survive and reproduce in these specific ways.”

    I don’t want to go through the entire debate again, but until you give a philosophically compelling answer to the question I asked about this the last time it came up, the above would seem to be based more on feeling than on sound philosophical reasoning. The two possibilities you’ve mentioned involve:

    1) God created the universe and the conditions in which harmful parasites and other harmful biological entities would emerge, and then passively sat back and let them cause pain and suffering even though he has the ability to help but chooses not to for reasons that are unknown to us.

    2) God created harmful parasites and other harmful biological entities directly and then sat back and let them cause pain and suffering even though he has the ability to help but chooses not to for reasons that are unknown to us.

    I fail to see how #1 is theologically preferable to #2. In both cases harmful biological entities emerge specifically because of what God has done, and in both cases God has heretofore seemingly done nothing to stop the pain and suffering that results. For those who accept the two choices you’ve offered yet hold that God is both real and blameless for such pain and suffering, I see two options:

    a) Attribute weakness to him and say that he either (i) lacked the ability to foresee that such harmful biological entities would emerge, and/or (ii) lacked the ability to create a universe without such harmful entities, and/or (iii) lacked the ability to help once they emerged.

    b) Grant that He had morally sufficient reasons for directly or indirectly causing such harmful entities to emerge and for allowing them to cause pain and suffering.

    I’m not sure whether liberal Christians would accept a, but Christianity as a whole has rejected such a notion. So, it seems to me that all who accept that 1 and 2 are the only plausible possibilities, yet choose to reject a, are stuck with b.

    • Susan Burns

      There could be c) Control is intrinsically immoral.

      • Kaz

        I think that would rule out the control imposed upon the emergence of the universe so that it was fine tuned for the existence of life in the first place. Also, that suggestion would seem to necessitate that it would be immoral for God to do anything other than allow the existence of that which hurts us, in which case the Christian hope of the resurrection to everlasting life as part of God’s good kingdom would itself be immoral.

        • Susan Burns

          You are assuming that the emergence of the universe was predicated on control. I don’t think so. Where is your proof of fine tuning? I don’t see any evidence of that. “God” obviously not only allows that which hurts us but also helps. In other words, absolutely no intervention whatsoever.
          Where I see God in biology and every other physical and cultural construct is that we are continuously evolving toward the good. From every bad thing that happens, something good emerges. Even though President Bush was responsible for killing thousands of innocent people, the Arab Spring would not have been possible without the elimination of Saddam Hussein (as an example).

          • Kaz

            I don’t think there’s really any questioning the fact of fine tuning. That’s why cosmologists put forth the hypothesis of the multi-verse or “landscape”, i.e. because the fine tuning of the constants and quantities was/are so unimaginably precise that some have posited an infinite number of universes in a bizarre effort to account for the fact that a universe as unlikely as ours could exist by chance.

            • Kaz

              Please replace “…to account for the fact…” with “…to account for the proposition…”

              • Susan Burns

                Fine tuning is just another way to say Intelligent design and intelligent design is just another way to say creationism. Whenever I converse with creationists, it always comes down to their lack of understanding of the process of evolution. It is not “chance” that created our universe, it was the repeated destruction and recreation of the simple to the more complex. I really don’t see why you would call that unlikely.

                • Kaz

                  I’m afraid that you’re mistaken, Susan. James acknowledges fine tuning yet rejects intelligent design, so one isn’t really equivalent to the other. Let me repeat, it is because of the fine tuning of the constants and quantities of the universe that cosmologists were compelled to postulate the existence of an infinite ensemble of universes. The question isn’t whether there is fine tuning, but whether the fine tuning required a fine tuner. The multiple universe hypothesis was a desperate attempt to offer some theory, however implausible or downright bizarre, to answer that question in the negative. I’m not so desperate to deny God, so I can comfortably answer in the affirmative.

                  In my very first post I indicated that I didn’t want to resurrect the previous debate, but really just wanted to remind James of the issues he faces, or, more accurately, that we both face. I’ve made my point, and you disagree, and that’s fine by me.

                  • Susan Burns

                    I don’t know what previous debate you are referencing. If by “fine tuning” you mean that an organism becomes more adapted to its ecological niche then I can agree.

                    • Kaz

                      The fine tuning I’m referring to has to do with the physical laws of the universe, which make the existence of biological life possible in the first place. Cosmological fine tuning has nothing to do with biology except insofar as it makes biology possible.

            • Beau Quilter

              No Kaz. Multiverse theories, though occasionally applied to “fine tuning” ideas by a few, were not invented to resolve “fine tuning”.

          • Kaz

            “Where I see God in biology and every other physical and cultural construct is that we are continuously evolving toward the good.”

            If that’s the case, then you reject the form of the evolutionary theory that is widely accepted, even by James. Scientific evolutionary theory has nothing to do with evolution producing what is “good” or “bad”. An unguided process, by definition, can’t guarantee that change will tend towards “good”. Only and evolutionary process that proceeds according to guidance can inevitably tend towards “good”, and that is a form of intelligent design. Good to have you aboard;-)

            • Susan Burns

              I realize that evolutionary theory does not account for attributes that could be termed good or bad. However, that is what is happening – at least on the cultural level. We are becoming less controlling which I think is instrinsically immoral. Therefore, we are evolving toward the “good”.

            • Jason

              Evolutionary theory does suggest that biological life gets more complicated over time.
              I think one could make an argument that more complicated brains allow
              higher level reflection (resulting e.g. in the concept of human rights)
              and thus something we might reasonably call good.

    • James F. McGrath

      I think that, if evolution provides a process whereby sentient beings can be created with an epistemic distance from God that allows for free will and other important things, in a manner that creating two full-formed humans pre-programmed would arguably not, and if that is considered a worthwhile goal, then the evolutionary process that brings that about could seem worthwhile, even though it produces nor only cooperation and sentience and kindness but also parasitism and competition. Indeed, it may be that some things we deem “evil” may be necessary to a well-functioning universe – the idea that we should have remained in some Edenic state or that that is ideal is not persuasive to everyone. In both such cases, these evolutionary products make sense in a way that they may not, theologically, if viewed as the direct intentional creation of a supposedly good and benevolent and all-powerful Creator who creates each organism directly.

  • BibleBeliever3000

    “The question I want to ask is what young-earth creationists and others who reject evolution say about such organisms.”

    All animals, including this one, were strict vegetarians prior to the fall.

    • James F. McGrath

      OK, so does that mean that you think Adam was a bioengineer? Or is that just a way of saying that God redesigned this creature to eat the tongues of fish as a deliberate act to punish fish for Adam’s sin?

      • BibleBeliever3000

        The second one. Suffering was introduced to the world as a result of the fall, and all living things were made to suffer. Don’t feel too bad for this fish, though. Its suffering is nothing compared to what green horn worms go through at the hands of braconid wasps.

        • Kaz

          I wonder if it’s necessary to even accept the second one. Oscar Wilde explored the notion that moral decay leads to physical decay (i.e. in A Picture of Dorian Gray), and I suspect that he may have been on to something. The question is, did the physical decay occur because God inflicted it, or because God withdrew his blessing and allowed the ramifications of sin to run their course?

          • BibleBeliever3000

            The Bible shows God delivering a curse at the fall, so that sounds like it happened because God inflicted it, but the Bible doesn’t go into a lot of detail here, so there are a lot of Christians who believe either of those possibilities you mentioned.

            The Answers in Genesis link I posted earlier suggests that carnivorousness is a result of a combination of genetic reprogramming and learned behavior as a response to scarcity.

            • Kaz

              True, but my question is, does the curse necessarily imply that God directly transformed creation into something unnatural, or at least unoriginal, or did it involve God’s allowing man and the creation over which man had dominion to suffer the necessary ramifications of his own sin?

              • BibleBeliever3000

                That’s an interesting theological question. I don’t know the answer.

              • Gary

                No curse. Why should humans be punished for seeking knowledge, good or evil? The whole Genesis thing is symbolic. Gnostics pictured Christ on the cross as the fruit of knowledge on a tree. Symbolism.

            • Caleb Gates

              If you study biology closely, changing vegetarians into carnivores, and previously harmless animals into parasites is not just genetic reprogramming, but rather a second creation event. These adaptations bear all the marks of exquisite “design.” But Genesis 3 gives no indication of such a second creation event. This is a perfect example of how Genesis inhabits a world foreign to the modern scientific understanding of the world.

              James Stambaugh has no scientific training. Furthermore he offers no scientific evidence to support his position. If Stambaugh’s model is correct then no carnivorous and parasites should exist before humans. But parasites and carnivores existed for millions of years before humans. William Demski tries to get around this by arguing that God back-loaded the results of the fall millions of years before human sin, but I fail to grasp what purpose God would have in human sin causing a T-rex to eat a Triceratops 65 million years ago.

              • BibleBeliever3000

                That’s true according to what people with scientific training or old earth creationists like William Dembski would say, but I was answering the question in the article was about what young-earth creationists would say. If we are discussing that, then references to events that occurred millions of years before humans, as if such things are settled facts, aren’t really relevant.

                What we’re talking about here is the belief that dinosaurs and humans were created on the same day just over 6000 years ago, so dinosaurs predated humans by a few hours at most, not by millions of years. The Bible doesn’t say how much time passed between the creation and the fall, but it was probably only a few weeks at most. So, animals such as lions, tapeworms, peregrine falcons, and Naegleria fowleri lived as strict vegetarians only for a very short period of time before God cursed them.

  • Brandt Hardin

    Here in TN, they have taken steps though new legislation to allow creationism back into the classroom. This law turns the clock back nearly 100 years here in the seemingly unprogressive South and is simply embarrassing. There is no argument against the Theory of Evolution other than that of religious doctrine. The Monkey Law only opens the door for fanatic Christianity to creep its way back into our classrooms. You can see my visual response as a Tennessean to this absurd law on my artist’s blog at with some evolutionary art and a little bit of simple logic.

  • Jonathan W. Hendry

    The latest “Laundry” novel by Charles Stross may be of interest. I can say no more.

  • arcseconds

    why is the sea so weird ^H^H^H^H a nightmare without end?

    If Cymothoa wasn’t enough to give you nightmares, check out these zombifying parasites/parasitoids:

  • Sylvia

    Why do we have this urge to apply human values to Nature? Good, bad, parasite, beneficial are all arbitrary categories. Why can’t we accept Nature as it is?
    Study it, learn from it, protect and restore it if needed but refrain from sticking a label on it.