Worm emerges from parasitized spider

Matthew Cobb, who has a penchant for parasites, sent me this video that was recently posted on YouTube. WARNING: if you’re squeamish you may find it distressing. But that’s nature, folks!

The caption says this:

ok so i was just editing my latest montage and this huge spider came out, so i sprayed it and killed it, then this fricken alien worm came out of it!!!

One commenter noted (and this looks accurate) that it’s a “Gordian worm,” also known as a “horsehair worm.” They constitute their own phylum, the Nematomorpha. Curiously, although they infest some terrestrial arthropods, like this spider, nematomorphs must reproduce in water. The article on the phylum in the Encyclopedia of Life notes that they might be quite devious about this:

Many types of parasites are known to modify the behavior of their host in ways that benefit the parasite. Based on anecdotal observations, it has long been suspected that at least some mature nematomorphs, which must reach water to mate and reproduce, manipulate the behavior of their terrestrial insect hosts, causing them to seek water and jump into it. Investigations by Thomas et al. (2002) found clear evidence of this phenomenon in 8 tettigoniid orthopterans infected by the nematomorph Spinochordodes tellinii, as well as in the gryllid cricket Nemobius sylvestris infected by the nematomorph Paragordius tricuspidatus. In experiments, however, they found no evidence that hosts actively seek out water; rather, they suggested, infected hosts seem to display erratic behavior that eventually brings them close to water, which they then enter. Consistent with the findings of Thomas et al. (2002), Sanchez et al. (2008) found that this behavioral manipulation has two phases, first causing the cricket to wander into atypical habitats and next causing it to commit suicide by entering water.

The evolution of the ability of parasites to manipulate their host’s behavior in an adaptive way is one of the most fascinating areas of organismal biology. In almost no case do we know how they do it. It’s mind control, pure and simple.


  1. Matthew Cobb
    Posted January 11, 2013 at 1:36 pm | Permalink

    I didn’t think you’d dare, Jerry! Now show us the video of the nematode exiting the beetle!

  2. blitz442
    Posted January 11, 2013 at 1:38 pm | Permalink

    The relationship between the worm and the spider appears to be irreducibly complex.

    • starskeptic
      Posted January 12, 2013 at 1:25 pm | Permalink

      …which came first? – in other words…

      • gbjames
        Posted January 12, 2013 at 1:27 pm | Permalink

        I would imagine this particular spider came before this particular worm. Jesus put him there so that Wormie could have a feast.

        • starskeptic
          Posted January 12, 2013 at 1:40 pm | Permalink

          You’re drawing a conclusion not supported by the info provided; the spider could have been produced by the actions of the worm – because we KNOW Jesus likes worms better…

          • gbjames
            Posted January 12, 2013 at 1:42 pm | Permalink

            “We’ll have to prey on that.”

            That’s a direct quote from the worm.

            • starskeptic
              Posted January 12, 2013 at 1:48 pm | Permalink

              Spider-shaped-mobile worm cocoon has people baffled – “why doesn’t this make Jesus cry?” , asks one Discovery Institute employee posing as a scientist.

  3. Posted January 11, 2013 at 1:43 pm | Permalink

    It looks like a piece of whole wheat spaghetti come to life–as in Byron and Shelley’s conversation, recounted by Mary Shelley, about Dr. Darwin’s supposedly having “preserved a piece of vermicelli, till by some extraordinary means it began to move with voluntary motion.” Presumably this is Grandad Erasmus.

    Anyway, the more I learn, the more it seems spiders are more sinned against than sinning. Yet another reason to read Carl Zimmer’s “Parasite Rex.”

    • Matthew Cobb
      Posted January 11, 2013 at 1:47 pm | Permalink

      Tell that to the flies…

  4. MadScientist
    Posted January 11, 2013 at 1:55 pm | Permalink

    See, the spider was perfectly designed to fit that worm in it. A human could never pack a worm that size into a spider that size.

  5. Marella
    Posted January 11, 2013 at 2:10 pm | Permalink

    Ewwww, I’m eating my breakfast! That was really nasty, poor spider, presumably it came out of hiding at the instigation of the worm which wanted water to reproduce in, that didn’t go so well.

  6. Posted January 11, 2013 at 2:27 pm | Permalink

    Don’t worry, if any of you get that worm in you I’ll do for you what Matt did for the spider…and I’d expect the same in return.

    • Matthew Cobb
      Posted January 11, 2013 at 2:34 pm | Permalink

      I DID NOT MAKE THIS VIDEO! I saw it on Twitter and sent the link. I wouldn’t have known about the worm because I wouldn’t have killed the spider! (Never mind the music…)

      • Diane G.
        Posted January 11, 2013 at 3:50 pm | Permalink


      • Timothy Hughbanks
        Posted January 11, 2013 at 10:52 pm | Permalink

        It was a mercy killing.

    • suwise3
      Posted January 11, 2013 at 2:34 pm | Permalink

      and did he hear the little voice saying, “Kill me!”?

      • Posted January 13, 2013 at 12:30 pm | Permalink

        No the little squeaky voice he heard was saying “help me! help me!

        • suwise3
          Posted January 13, 2013 at 2:02 pm | Permalink

          At that point, with both of them lying in a pool of insecticide, could be either one saying either phrase…

  7. Roger
    Posted January 11, 2013 at 2:48 pm | Permalink

    I think it is proof of the FSM.

  8. Brian
    Posted January 11, 2013 at 2:50 pm | Permalink

    Yet Coyne doubts that different male and female behavioral means /stdvs on many variables might differ owing to differential reproduction based on different strategies that yield successful reproduction.

  9. Torbjörn Larsson, OM
    Posted January 11, 2013 at 3:26 pm | Permalink

    You can see how the photographer thinks “KILL IT WITH FIRE!”, but had to settle for poison.

    I wonder where the spider’s religious “free will” went?

  10. Posted January 11, 2013 at 3:26 pm | Permalink

    I always wonder how some of these parasites fit into the hosts, especially together with enough organs to keep the host marginally functioning…

    • still learning
      Posted January 11, 2013 at 3:51 pm | Permalink

      Exactly what I was thinking.

      • thh1859
        Posted January 12, 2013 at 5:25 am | Permalink

        And me.

    • Diane G.
      Posted January 11, 2013 at 3:52 pm | Permalink

      I think the latter is the most amazing part. Even if the prey is paralyzed, parasites “know” what parts to eat in what order to keep the host alive as long as possible.

      • Posted January 11, 2013 at 8:41 pm | Permalink

        My husband keeps asking “How do they know [how] to do that?” questions, and my answer is almost invariably the same:
        “If they don’t, they die.”

        • Diane G.
          Posted January 11, 2013 at 10:26 pm | Permalink

          Indeed. “Knowing” in the evolutionary sense is different from “knowing” in the Biblical sense. Altho that latter sense does enter into it…


  11. taupossaft
    Posted January 11, 2013 at 4:13 pm | Permalink

    You can find other funky videos of this parasite here: http://goo.gl/KolWr
    The gordian worm has the capability of hijacking its host nervous system and pushes it to drown itself in the nearest water pond. But it’s also capable of escaping the mouth or gills of their host predator!

  12. Posted January 11, 2013 at 4:38 pm | Permalink

    Such restraint! I don’t know how you managed to write the bit about nematomorphs manipulating their hosts to seek out and hurl themselves into water without making an “Itsy, Bitsy Spider” reference. Now we finally understand that wayward arachnid’s obsessive behavior in returning to the waterspout over and over.

    • Posted January 11, 2013 at 11:46 pm | Permalink

      “Itsy, Bitsy”? Strange dialect. Everyone knows the Correct Pronunciaiton is
      “Intsy Wintsy”!

      • starskeptic
        Posted January 12, 2013 at 12:33 pm | Permalink

        Not strange at all – it’s a regional thing…

        • gbjames
          Posted January 12, 2013 at 1:11 pm | Permalink

          I don’t know.. I think regional things are all strange! except mine 😉

          • starskeptic
            Posted January 12, 2013 at 1:23 pm | Permalink

            That IS strange!

            • MastrNinjaMonkey
              Posted September 23, 2013 at 9:48 pm | Permalink

              I’ve always thought it was “itsy, bitsy’ also, hmmm…

  13. cremnomaniac
    Posted January 11, 2013 at 5:16 pm | Permalink

    Holy horsehair Batman!
    that thing must have occupied half of the spiders internal cavity.
    Incredible, and a little creepy.

  14. Geoff
    Posted January 11, 2013 at 5:21 pm | Permalink

    Wait… Some dude found a spider THAT big in his house and the worm is what’s upsetting?>

    • starskeptic
      Posted January 12, 2013 at 12:36 pm | Permalink

      …depends on what you’re used to, I guess. FWIW, never hit a Tombstone Jack-rabbit with a car doing 70 mph – it just pisses them off…

  15. Scott Reilly
    Posted January 11, 2013 at 5:50 pm | Permalink

    I remember reading that the cricket population in Hawaii has undergone rapid evolution by NS as a result of being preyed upon by parasites. The parasites home in on the male crickets as they chirp trying to attract mates, and the parasites lay their eggs inside. A mutation eventually arose allowing for quieter chirping in the crickets, which meant it was more difficult to attract a mate but less likely they would get killed by parasites. Now most of the cricket population chirp quietly.

    Pretty Cool!

    • Marlene Zuk
      Posted January 12, 2013 at 9:26 am | Permalink

      Can’t resist — that’s our research, and I am really flattered that someone remembered it in relation to this. Actually it’s a single gene mutation that completely eliminates the male’s ability to call. It spread remarkably quickly, within 20 generations or fewer. A few of the callers remain on both of the Hawaiian islands where we’ve studied the system, and we think that’s essential for maintaining the new morph.

      • Scott Reilly
        Posted January 12, 2013 at 6:26 pm | Permalink

        Hi Melaine

        That’s really cool. I remember now, I did this online course and your research was mentioned as evidence for rapid evolution. https://www.coursera.org/course/geneticsevolution

        You mentioned that a few of the callers remain on the islands. But wouldn’t the presence of the parasite cause the total loss of that allele.

        Also, I’m curious as to how the parasite actually gets its eggs inside the crickets. Do they have to bore a hole or make a cavity in the cricket somewhere. Why doesn’t the cricket act to remove it?

        Sorry about the questions. I find this really fascinating

        • Marlene Zuk
          Posted January 13, 2013 at 9:50 am | Permalink

          Don’t apologize for the questions — happy to have the opportunity to talk about my lab’s work! We think the presence of some callers is crucial to the maintenance of the system. The flatwings (as we call the silent morph) are attracted to song, and the females seem to be more likely to interact with them as the females themselves move toward the callers. And while the callers are at risk from the fly, they are also much preferred as mates. So we think that selection acts in a frequency-dependent manner: the presence of few callers makes those few even more likely to mate, which will increase their relative abundance. But then the flies will increase, which makes the flatwings more likely to survive, which in turn decreases the fly abundance, and so forth.

          As for the entry of the parasite, flies lack the hardened ovipositor that parasitic wasps possess, so they deposit mobile, free-living larvae on and around the cricket. The larvae are sticky and burrow inside the cricket on their own. Grooming does work sometimes to get them off, but is not totally successful.

          • Diane G.
            Posted January 13, 2013 at 1:40 pm | Permalink

            Very interesting discussion. Thanks, Marlene and Scott!

          • Mark Joseph
            Posted January 13, 2013 at 5:55 pm | Permalink

            Dr. Zuk:
            I recently finished reading Matt Ridley’s “The Red Queen”. While I found the entire book fascinating, the single most fascinating part might have been the section on parasites, resistance, and sexual selection, including the “Hamilton-Zuk parasite theory”. So much so that I actually looked further into your website and the papers listed in the book’s bibliography.
            I notice that the end of your first paragraph above, from “So we think that selection acts in a frequency-dependent manner” on, sounds much like a Red Queen type of reasoning.
            Thank you for showing up here!

  16. Chris
    Posted January 11, 2013 at 5:59 pm | Permalink

    Clearly, this is the sign of intelligent design and a loving creator! NOT….

    • Old Rasputin
      Posted January 12, 2013 at 9:38 pm | Permalink

      As long as the creator loves worms I don’t see any theological conflict. Clearly He gave them dominion over the other animals; we’re just here to serve as hosts.

      It doesn’t make much more or less sense than the arbitrarily human-centric theologies that are being peddled these days.

  17. marksolock
    Posted January 11, 2013 at 8:38 pm | Permalink

    Reblogged this on Mark Solock Blog.

  18. Posted January 11, 2013 at 8:48 pm | Permalink

    “Manipulate” is a recurring word in the descriptions here of parasite and host. But “manipulate” is a term about human skill and social interaction and it’s probably limiting our understanding of what’s taking place biologically. When we understand this phenomenon more clearly, it might turn out that “manipulate” is not what’s happening at all.

    • John Scanlon, FCD
      Posted January 12, 2013 at 2:12 am | Permalink

      Because Gordian worms have no hands? (Latin manus)

      It’s OK to speculate that nothing is really as we think it is, but unless you can propose a test that could falsify a current hypothesis, it’s not really going anywhere.

  19. Posted January 11, 2013 at 10:03 pm | Permalink

    I’m really glad I ate my spaghetti dinner before watching that video and not after. Don’t think I’ll be touching the leftovers for a while, though!

    Thanks for including the Encyclopedia Of Life article; it turned the video, which was viscerally repulsive, into something completely fascinating.

    Hmm…that leftover spaghetti’s lookin’ better already…

    • gravelinspector
      Posted January 12, 2013 at 9:01 am | Permalink

      Clearly you have been touched by the Noodly Appendage!

  20. Posted January 11, 2013 at 10:31 pm | Permalink

    It’s an interesting catch 22. The amount of redundancy in an organism (eg. how much of your liver you can lose and suffer no noticeable effects, needing only 1 kidney/1 lung, etc.) versus the waste of resources to provide that redundancy which can be exploited by a parasite. One might expect that an organism would try to be as efficient as possible, which would make it much more difficult for a parasite to take advantage of it.

    • John Scanlon, FCD
      Posted January 12, 2013 at 2:21 am | Permalink

      …try to be as efficient as possible, so that any parasite attack would be lethal to both parasite and host. That’s the Doomsday Device approach, which only works if you can inform the enemy in a convincing way that the device is installed and will be triggered automatically, and if the enemy is rational. Getting the information across to every single parasite (down to viruses) makes this an impractical strategy, and will not compete successfully vs having a second kidney, an immune system, etc.

  21. starskeptic
    Posted January 11, 2013 at 11:30 pm | Permalink

    Matthew needs to supply more info…what brand of bug spray causes this?

  22. d
    Posted January 12, 2013 at 1:20 am | Permalink

    Knee-jerk instinct to torture a spider to death with poison; I’ll never grok that.

  23. Posted January 12, 2013 at 4:46 am | Permalink


    • starskeptic
      Posted January 12, 2013 at 11:15 am | Permalink

      Dead Goa’uld – if it doesn’t find another host.

  24. Old Rasputin
    Posted January 12, 2013 at 8:10 am | Permalink

    Isn’t there a worm that does this in humans? It develops and grows inside the host and then when it’s mature causes severe itching and burning, inducing the poor fellow to seek out water, at which time it bursts through the skin and sets out on the aquatic phase of it’s life cycle. They are supposed to be quite painful and were once common in some parts of Africa. Does anyone remember what these are called?

    • John Scanlon, FCD
      Posted January 12, 2013 at 8:31 am | Permalink

      Guinea worm

      • gravelinspector
        Posted January 12, 2013 at 9:05 am | Permalink

        Only one species / genus / family.
        I was thinking about (IIRC) pin worm, which need to cycle from human anus back to the human mouth, and achieve this by causing severe anal itching.
        Usual caveats : I’ve been told ; I’ve not experienced this myself, though something like 1/3 of the adult western population carries the parasite.
        I wonder what the transmission routes for Helicobacter are, if anyone knows.

        • John Scanlon, FCD
          Posted January 12, 2013 at 11:29 am | Permalink

          Googling… How about this? Viable and pathogenic H. pylori reported to be associated with a marine copepod in the Adriatic Sea.

          I don’t know if that’s a regular transmission route, but WTF’s up with copepods? It’s like they’ve got it in for us.

      • Old Rasputin
        Posted January 12, 2013 at 9:39 pm | Permalink

        Thank you, sir.

  25. Posted January 12, 2013 at 8:33 am | Permalink

    That is of unbelievably gross, send shivers from head to toes. Aint gonna sleep at all tonight 🙂

  26. Strider
    Posted January 12, 2013 at 9:42 am | Permalink

    I’ve seen these beasties emerge from Ceuthophilus stygius, an orthopteran that often uses caves, and I’ve always wondered how the bloody orthopteran *lives* playing host to that much worm.

  27. acitta
    Posted January 12, 2013 at 11:28 am | Permalink

    So why is it that upon seeing a spider, the first reaction of some people is to spray it with insecticide? I have yet to come across a man-eating spider.

    • starskeptic
      Posted January 12, 2013 at 11:36 am | Permalink

      Lots of man-poisoning spiders though…

      • acitta
        Posted January 12, 2013 at 11:52 am | Permalink

        Not where I live. Anyhow, I have never heard of spiders actually attacking human beings with the intent to kill them.

        • starskeptic
          Posted January 12, 2013 at 11:59 am | Permalink

          Neither is really to the point as to why we have that reaction.

        • gbjames
          Posted January 12, 2013 at 12:03 pm | Permalink

          Doesn’t much matter what the intent is does it?

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