I think I found something in your book More of the Straight Dope that could be described as a mistake, although I wouldn’t use so vulgar a term. You said the reason worms crawl out on the sidewalk when it rains is to avoid drowning when their holes fill with water. A few months ago, after the author of an article in Discover magazine made a similar claim, a scientist who studied worms wrote in to say worms can live underwater as well as in the dirt. They don’t breathe as we do but get oxygen in some way that makes drowning an impossibility. He said the reason they come out was mating. –Brad Campbell, Seattle
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Hmm. The wormologist in question is Richard Wahl of Shippensburg University in Pennsylvania. He writes: “Worms do not drown when it rains. . . . Worms of all kinds are highly susceptible to dessication [drying out]. They breed when it rains. They come out of the ground to find each other and to lie side by side in a mating posture, a difficult thing to do in the confines of their burrows. [And we complain about the back of a Ford!] The only time earthworms can safely come to the surface to breed is when the ground is thoroughly soaked…. Worms don’t have lungs.”
We know that worms will dehydrate and die if exposed to dry conditions for even a few hours. But they do need to leave their burrows once in a while, either to find new quarters when the old neighborhood gets crowded or do the wild thing (for a worm) with members of the opposite sex. Usually the only safe time to do this is at night; that’s why they call them night crawlers. But worms can also do it when the ground is soaked after a heavy rain.
