Ceci n’est pas une fourmi

January 19, 2013 • 11:31 am

Nope not an ant, as photographer/entomologist Alex Wild explains (my emphasis):

The delicate build and sabre-like pedipalps of this Brazilian clubionid spider help it to mimic the painfully-stinging trap-jaw ants of the genus Odontomachus. Photo from Morretes, Paraná, Brazil.


What a great example of mimicry! Count the legs (I think one is missing, but there are clearly >6!).  I’m not sure which species they mimic, but here’s an Odontomachus brunneus (an ant!) from Wikipedia:


27 thoughts on “Ceci n’est pas une fourmi

  1. An important question in the case of all mimics is what observer the mimic is attempting to deceive.

    Is the spider trying to trick ants into accepting it as one of its own, or is some other species the target of its illusion?

    Obviously, it’s a species that relies at least in part upon visual identification…but is there also any chemical mimicry going on? Sounds, too? Maybe even surface texture…?


    1. Probably trying to deceive birds or something else that hunts by sight. I’m thinking that ants rely more on chemical signals for recognition.

    2. …what observer the mimic is attempting to deceive.

      Is the spider trying to trick ants into accepting it as one of its own, or is some other species the target of its illusion?

      Such ant-hropomorphism! None of the ganglia of that ant, nor those of any of its ant-cestors for millennia in the past, has ever formed any such intention, or indeed any intention.

      But what is a quick and accurate way of describing what is going on?

      “…what observer is deceived by the mimic.

      Are ants deceived into accepting it as one of [their] own, or does some other species attract the arrows of its illusion?”

      That metaphor is much too cumbersome, and even “deceived” implies a degree of consciousness about what they ought to be seeking/avoiding.

      “…what observer’s mistake the ant (most) benefits from.

      Has it evolved in such a way that ants mistake it for one of their own, or so that some other species treats it – whether by assistance or avoidance – as an ant?”

      Improvements welcome.

  2. As I understand it, spiders and other arthropods mimic ants b/c they are bad tasting, and some ants can sting. So they are mimicking something unpleasant. We have a local jumping spider that is an ant mimic. It is amazing how they look like the real thing, then you count the legs.

  3. I instantly recognized it as not an ant (the fake mandibles give it away), but I couldn’t guess what it was. But how do we know it isn’t the ant mimicking the spider?

    1. The ants are big, common, and conspicuous shiny black and easy to see on the forest floor. They are active as isolated forragers but attack in mass if a nest is disturbed. The sting of the ant is formidable, like that of a wasp. I suspect that insectivorous birds and small mammals learn to avoid them. Mimetic spiders, on the other hand, are much less common and do not seem to have much of a bite (I’ve never heard of a case of a painful bite, while the ant is well known for its sting). Not much in the line of tropical forest vertebrates seem to eat ants.
      In my opinion experimental proof of mimicry would require cruelty to the test animal. My was d*g visibly distressed after being stung on the tongue. The cats seem to know better.

  4. Never realized how much I disliked how insects looked until I started following these posts. As awesome as this mimicking is, hah.

    How am I supposed to pluck ants off my shoulders or throw spiders outside knowing they look so… *shudder*

    1. I suggest that you not look at these posts if they cause you such discomfort.

      And your comment is unnecessarily rude.

      1. I’m curious what about Shinashi’s post you find rude. I suppose it may have been edited but looking at it now I can’t see anything that insults either you or your site in any way. All it says is that dislikes insects.

        1. + 2

          Came across to me as a self-reflective comment and a bit of humor at his own expense.

          (Not to mention interesting for its mention of involuntary revulsion, as other commenters have noted.)

    2. I find Shinashi’s reaction interesting, and not uncommon. Is this revulsion evolved? Why does it seem that it is more common among women than men (sorry, no citation, just my own feeling)? I can pick spiders up from the bath and put them outside, but Mrs Brains leaves a toilet paper ladder for them to climb out by themselves, preferably once she has left the room.

    3. Shinashi,

      My reactions have been the opposite. My gut reaction to pictures of spiders, flies, ants, etc. used to be one of mild to strong “ick”, and maybe a bit of morbid fascination, but after reading the text and learning more about them they seem really interesting and now I see the images in a different light–one in which they appear beautiful in their own way. May I suggest that if you stick with the posts your esthetics may change, or evolve, as it were? Meanwhile, good luck keeping the ants off your shoulders!

      1. Lady I am!

        That’s the thing- how interesting it all is. I thought it was a close up of a terrifying ant, and then I read the comments about the whole ‘mimic’ thing, and I was forced to take a closer look. “Ick” was strong.

        But the dead spider with the parasitic worm (the camera was far enough away from that)- I had no problem with that and was showing it off to others ’cause I thought it was awesome.

        I’m confused on why certain magnification scares me. (It’s actually the same with magnification of skin pores, or dust, or non-moving cells…)

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