Monday, March 17, 2008

Season's Spinning Round Again

Spring is almost here. And it's not just the calendar that tells me this. More importantly the worms are back. They lie twisted and flaccid along the edges of my driveway or pink and swollen along the sides of the road - looking as if they were washed ashore by the mid-March rains that have soaked into the recently unfrozen earth.

But then I wonder - where have they been for the past bitter cold months? Did they migrate to a warmer climate along with the birds that feed upon them - grouped together in tiny vee formations inching their way along I 95 South? Did they hibernate - fattening up and then deliberately slowing down their metabolisms as they hunkered down in their winter bunkers? Or did they just crank up the heat in their little worm burrows, throw on a couple of layers of red flannel fleece, bundle together, and sip on cups of hot chocolate for warmth?

Actually, according to Google's number one answer to the query "worms winter":

While other creatures are winging and swimming south as you read this, underground worm activity is also at a peak. Surprised? Fall and spring are a worm's favorite seasons! Dark, cool, and moist. That's how worms like it. Believe it or not, worms are responsible for eating many of the fallen leaves and debris that result from autumn season. They hang around because there's good stuff to eat, and they like the cool temps and moist conditions fall brings.

When temperatures drop or soils get too warm or dry, worms know what to do. If it starts getting chilly, many kinds of worms tunnel deep into the soil before it freezes. Worms "migrate" downward, burrowing deeper to get past the frost. Sometimes they dig six feet deep! There they stay in their burrows, prisoners below soil frozen hard as rock and topped by ice and snow. They coil into a slime-coated ball and go into a sleep-like state called estivation, which is similar to hibernation for bears. (The mucous, or slime, keeps the worms from drying out.) Worms will survive in frozen or dry soils by estivation until conditions improve.

Wow! There's an awful lot of stuff in there that I just didn't know - plus this additional vocabulary lesson provided by my online dictionary.

estivation (also aestivation)

1 Zoology prolonged torpor or dormancy of an animal during a hot or dry period.
2 Botany the arrangement of petals and sepals in a flower bud before it opens. Compare with vernation.

noun Botany
the arrangement of young leaves in a leaf bud before it opens. Compare with estivation .
ORIGIN late 18th cent.: from modern Latin vernatio(n-), from Latin vernare 'to grow (as in the spring),' from vernus (see vernal ).

of, in, or appropriate to spring: the vernal freshness of the land.
vernally adverb
ORIGIN mid 16th cent.: from Latin vernalis, from vernus 'of the spring,' from ver 'spring.'

Granted my wordbook's definition of estivation talks about "dormancy.....during a hot or dry period", and the connection between estivation and vernation has nothing whatsoever to do with limbless invertebrates. Still it seems kind of strangely serendipitous that the path dictated by the dictionary's word citations led me from the behavior of worms in the winter to the arrival of spring, which of course is what started this whole thing to begin with. I remember once hearing the author William Least Heat Moon wondering whether outside events arranged themselves to answer the questions that we were currently asking, or whether they are always there and our curiousness just makes us aware of them.

Anyway, the worms are back because they never left. But why did they come to surface? According again to

Dr. Dennis Linden, Cindy Hale, and other worm experts say that worms do NOT surface to avoid drowning. In fact, they come to the surface during rains (especially in the spring) so they can move overland. The temporarily wet conditions give worms a chance to move safely to new places. Since worms breathe through their skin, the skin must stay wet in order for the oxygen to pass through it. After rain or during high humidity are safe times for worms to move around without dehydrating. It is true that, without oxygen, worms will suffocate. But earthworms can survive for several weeks under water, providing there is sufficient oxygen in the water to support them.

One more thing: Remember what can happen to worms left in sunshine or daylight? Their skin dries out and they can no longer breathe. Naturalist Jim Gilbert has this friendly advice: "Next time you see earthworms under your garage door or on your sidewalk after a rain shower, why not pick them up and put them in a shady garden spot so they can safely go back into the soil. This could be your way of thanking the earthworm population for many jobs well done."

So the totally motionless demeanor that I have been observing on my driveway must be just some kind of possum-like deception. These seemingly lifeless invertebrates are actually relocating themselves, at roughly half the speed of Xeno's paradox of motion, searching for the next best place to play their role in the cycle of the seasons.

As for my part: mulching my autumn leaves helps to feed the earthworms; transporting the languid little guys across the driveway hastens the nurturing of my pre-spring soil. Just like them, all my lifes a circle.

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