soil centipede

Back on May 10, this is one of the things that Sam and I found under a rock. We didn’t spot it at first, because it looked a great deal like a small plant root - at least until it moved. It’s almost two centimeters long, but less than a millimeter wide.

It’s a soil centipede, order Geophilomorpha. These are actually getting close to deserving the name “centipede” (”hundred-legger”), because for this one I count 39 pairs of legs (78 legs total). Some other species of soil centipede actually do have over a hundred legs.

An interesting point about centipedes (or at least, I think it is interesting): the different types of centipedes are actually quite distantly related to each other. Notice I said it was in the Order Geophilomorpha. The Stone Centipede that I posted a while back (and that we found under the same rock) is in the order Lithobiomorpha. Since they are in different orders, they are no more closely related to each other than, say, beetles are to butterflies. And other “myriapods”, like millipedes, are about as closely related to centipedes as they are to lobsters or spiders. I understand that the biologists currently think that the “myriapods” are pretty much what the ancestral arthropods looked like. We evidently have a bunch of distantly-related groups that, even though their last common ancestor was a long time ago, didn’t happen to evolve in a way that changed their body morphology too much. As a result, they still all look generally similar to each other even though they probably became separate groups sometime before there were dinosaurs.

Anyway, soil centipedes are generally carnivorous, and run under leaf litter and down earthworm holes to eat other small things that they find underground. These are enough smaller than the stone centipedes that I can’t really see them being any harm to anyone, and I don’t see any sign of poison claws in these pictures (although, to be fair, the heads are so small that it’s hard to see details). They evidently don’t have eyes, because, well, why would they have them? What is there to see under a rock, anyway? Normally, you probably won’t even notice these until you go specifically looking for them, but as soon as you look closely they are probably all over the place anytime you start digging.