Worms and Millipedes in the Snow
A special Easter bonus posting. Two postings in one weekend! Plus snow!
Early yesterday morning (Saturday, April 23, 2011), we had what I sincerely hope was our last serious snowfall of the season [1] . We got a couple of inches by about 7:30 AM, when I went outside to get the saturday newspaper.
Once outside, I noticed that there were a number of what looked like short twigs resting on top of the snow. Then I thought, “That’s odd – there’s no wind to break twigs off of trees, and it’s still snowing. Why would twigs be on top of the snow?” And looking closer, I realized that the answer was, “Because they aren’t twigs”.
They were, in fact, earthworms! Little earthworms, only a few millimeters in diameter and a couple of inches long, but earthworms nevertheless. What they were doing crawling around in the snow, I have no idea. They were certainly alive, too. When I picked one up, it curled up and contracted just like you expect a worm to do.
And yes, yes, I know earthworms aren’t arthopods. In point of fact, they are actually no more closely related to arthropods than we are. Still, they are small invertebrates that live in the yard, so I might as well include them.
Besides, it turned out some of the “worms” weren’t worms, but actual arthropods: there was at least one millipede crawling over the snow, too!
Normally, when you pick up a millipede, it curls up into a ball right away. This one curled up too, but veeeerrrrrrryyyyy slowly. Well, it was only 33 degrees F outside at the time, so really, I’m surprised the little feller was able to move at all!
Anyway, I’d never seen worms and millipedes on top of new-fallen snow before, so I had to get this one posted. As for what they thought they were doing, who knows? Earthworms don’t have much of a brain, I suppose they didn’t actually think about it at all.
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[1] Actually, this weather is not unusual for us. For example, two years ago, on April 22, I was trying to fly back to Houghton after a business trip, and we were so badly snowed under that I couldn’t get back home for two days (we got a couple of feet of snow that time). And, looking at three years ago on this very blog, I see I was complaining about a late blizzard around April 7. The only months where we are unlikely to get measurable snow are June, July, and August. I’ve been told (but haven’t been able to confirm) that if you check the records far enough back, there has been measurable snowfall recorded in Houghton for every month of the year, including July and August. That’s just the way it goes here, I guess.
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If skijorning is x-country skiing with dogs pulling you, what would it be with worms harnessed up?
Yes, I remember getting snow in August one year when I was in Houghton. It was measurable, but melted by mid-morning….
They mustn’t have much water in their bodies otherwise it would crystalize and break cell walls, right?
I think it is just that they weren’t quite cold enough to freeze. The worms I’ve seen die of dessication on the sidewalks over the years certainly look like they lost a great deal of water. The snow was just barely freezing, and the natural electrolytes in the worms’ body fluids was probably enough to depress their freezing points just enough. For that matter, they may very well have had natural antifreeze in their blood.
What do you call it when worms pull you through the snow? How about Vermibogganing?
Do you suppose that the chemistry of the fluids in their bodies changes with temperature? Do they produce more electrolytes as temperature decreases?
I don’t know if it is true specifically for earthworms, but I’ve read that a lot of small invertebrates that overwinter do boost their levels of electrolytes and antifreeze compounds in response to cooling temperatures in the fall. For example, if you lightly freeze a woolly bear caterpillar in the summer it will die, but if you lightly freeze one in late fall, it will generally survive.
I expect that these earthworms were still in “winter” mode, and so could survive the cold much better than “summer” worms would have.
Very strange!
Aaaahh, the millipede looks so contended in your warm hand. I bet it was disappointed when you put it back in the snow.