Banded Millipede

2011 February 5

The millipede posted back in January was photographed some years ago, but this one is more current. Sam found it under a rock in 2010, on March 14, which is, for us, just about the earliest time where you might conceivably be able to find a patch where the snow has melted. In this case, I think the rock in question was on the south side of the house, which is noticeably warmer than anywhere else in the yard.

These were unfortunately taken before I had invented the Cone Flash Concentrator, so the shutter speed was slow due to inadequate flash. Which means the pictures weren’t as sharp as they might have been. But, we can still see that this millipede has distinct pale bands between the segments, rather than being uniformly colored.

As you can see from it here in my hand, it was not a very large millipede, only maybe a couple of centimeters long.

Judging from the banding, it’s just barely possible that this is one of the species in the family Julidae, which are not native to North America (although this is a long shot, and it is probably another of the native species after all – but just for the sake of discussion, let’s assume it isn’t). Like so many other things, some of the Julidae millipedes hitch-hiked over from Europe. They probably were living in ship ballast, or agricultural products, or just hidden in dark, moist crevices on all sorts of imported products. And that’s probably how they spread over North America, too; by hitch-hiking. They aren’t very fast, so if they have gotten all the way up here I really doubt that they walked all the way from their initial introduction points on the East Coast.

Julidae are very similar to the native Parajulidae family (which, honestly, is much more likely to be what this specimen is), and have about the same lifestyle. They all mostly live in the leaf litter and under rocks, eating bits of organic debris that they find, and being toxic and unpalatable to anything that tries to eat them.

This one obviously wasn’t much bothered by cold, and probably spent most of the winter being somewhat active in the “subnivean environment”, the thin layer of above-freezing conditions where the snow touches the ground. The thing that millipedes in general can’t tolerate is dryness. Even though they look as if they should be well-sealed, they actually lack the waxy layer on their skins that other arthropods use to prevent moisture loss. This means that they dry out unusually quickly when they are exposed. So, if you try to keep them as pets, they really do need to be kept in moist conditions.

And speaking of pet millipedes, you can get live specimens commercially that range from large to positively huge. And they’re evidently both long-lived and easy to feed, it says that they do well on things like cucumbers and potatoes.

It’s too bad we can’t get live specimens from the heady days of the Carboniferous Period, back when arthropods were the dominant land animals and the largest myriapod was Arthropleura, at a whopping 2.6 meters (almost 9 feet!) long. Not to mention the giant dragonflies. There is a theory that the arthropods (and insects in particular) were so big in the old days because the oxygen content of the atmosphere was higher (about 35%, compared to 21% these days), and this overcame the limitations of their respiratory and circulatory systems that would otherwise keep them small. At least one recent study has, in fact, shown that most insects grow larger when the oxygen content of the air is increased. But, there is some argument about the ultimate importance of this. A competing theory is that the reason land arthropods used to be so big was simply that there was nothing else big enough to eat them at the time.

4 Responses
  1. February 5, 2011

    Assuming they arrived in Jamestown in 1607 and they spread 100 yards each generation (moving the length of a football field with Brownian motion when you’re that small seems a reasonable assumption), they would have spread 40,400 yards by now. That’s about 23 miles. That means they would have just about made it to the door of Willie’s BBQ by now.

  2. February 5, 2011

    Scratch that. I didn’t double check my distances on Google Earth. At 100 yards a year, they’d still have a few more years to make it to Willie’s. Oh well. I guess our multifooted friends will have to wait a bit longer for the taste of authentic Carolina BBQ.

  3. February 7, 2011

    KT: That’s OK, random walks are kind of unpredictable. They could easily have advanced a bit faster than predicted – I’m sure that Willie’s is at least within a standard deviation of the predicted location of the expansion front by now. Plus, the scent of a good BBQ joint might have made their expansion just a tad directional over the last couple of decades.

  4. February 7, 2011

    Let’s hope Willie’s doesn’t have a sign out front like this one.

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