Why Would Earthworms Leave the Grass?
You probably don't see earthworms out and about very often, except following a rainstorm. Especially in the springtime, rain brings earthworms out of their burrows and onto the sidewalks. Surprisingly, intuitive theories about why worms leave the grass when it rains aren't very accurate. Does this Spark an idea?
Other People Are Reading
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Not to Avoid Drowning
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According to the website Learner.org, many people think worms leave their burrows when it rains to avoid drowning. While it is true that worms need oxygen to survive, worms breathe through their skin and can actually absorb the oxygen they need from water. Earthworms can live comfortably under water for several weeks, as long as the water contains enough oxygen to support them.
High Relative Humidity
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Worms that leave the grass to crawl over driveways and sidewalks are actually responding to high relative humidity. A worm's skin needs to stay moist in order for it to absorb oxygen, so they can't survive long in dry environments. The air contains a lot of moisture following a rainstorm, making it safe for worms to migrate above ground from one patch of soil to another.
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Some Worms Don't Make It
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Sometimes, you might see a dried out worm left stranded on the sidewalk after too much time in the sun. Light paralyzes worms if they're out for more than an hour, which can happen if the sun suddenly breaks through when a worm's only made it halfway across your driveway. When the sun dries out a worm's skin, it can no longer breathe, causing the worm to suffocate.
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References
- Photo Credit worm image by Ksenija Djurica from Fotolia.com
