Thursday, June 05, 2008


This is a follow-up to my post, Wednesday morning, Down came the rain and ....

I wrote about a mysterious (to me) long worm that I found dancing in the rain. (The worm was dancing, not me. Just clarifying.)

I labelled it a roundworm, or nematode. Hugh, in the comments, suggested that it might be a horsehair worm. So I've been Googling again.

He's right. And I was wrong. It has all the characteristics of a horsehair worm. It is not a Nematode, but a Nematomorph. Which means "shaped like a nematode", so I wasn't that far out.

Wikipedia has a description of the phylum and a basic description of their life cycle. And at the NH Department of Environmental Services, I found a useful fact sheet, including:
Adult worms may be found in flowing or standing water including rivers, streams, vernal pools, ponds, and even pets’ water bowls. They are long (can grow up to two feet), thin (1/16th of an inch), and round, with inter- and intra- species color variation ranging from tan to black. Besides having a long and slender appearance, Gordian worms are unlike earth worms, in that they are not segmented. The body diameter is the same throughout most of the body’s length, with a slight taper at both extremities. The Gordian worm does not have a distinct head. Adults do not feed as their stomachs are degenerate (do not function) and their mouths are useless. They can be found either singularly or in masses, often wrapped around rocks, branches and each other.
  • Found in (or near) water? Yes, in the rain.
  • Not segmented? Check.
  • Body diameter equal along length? Yes.
  • No distinct head. Oh, yes. I spent a good part of my watching time trying to decide which end was the head.
  • Add to that, from Wikipedia, no cilia. Uh-huh.
  • ... longitudinal muscle and a non-functional gut, with no excretory, respiratory or circulatory systems. As far as I could see.
The adult worms don't need a functioning gut; they don't eat. They find a mate and start work on the next generation.

Wednesday evening, my worm was still alive, so I put him back in the planter where I found him. Today it was raining again, and he was back on his post at the top of the bird's head, swaying to some unheard beat.


PS. In the comments, Christopher links to a video of a horsehair worm emerging from its previous cricket host. Warning: it's not for the squeamish.


  1. You would have probably also discovered in your researches that nematomorphs live their juvenile years as parasites of insects, before driving the host to seek out water where the adult Gordian worm can emerge. I linked to a video of a Gordian worm emerging from a cricket a while ago.

  2. Thanks for that link! Wonderful, and terrible at the same time.

    It's almost unbelievable that such a long worm could fit inside a small cricket and still leave it room to function. And I wonder how it manages to convince the cricket to commit suicide.

    (Yes, I'd read about that, but it's easier to believe after I've seen it.)

  3. Ugh! But VERY interesting. I wondered how that long worm could fit in that cricket as well.


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