Mud Room
10:05 am
Fri March 7, 2014

Why Do Earthworms Love To Come Out In The Rain?

Some experts think earthworms surface after the rain because a moist surface makes an easier commute.
Credit Flickr Photo/Allan Henderson (CC By 2.0)

This week when I’ve asked my kids about their school day, their answers have been all about worms. Their recess playgrounds have been lively with earthworms surfacing, as they typically do during a rainy week like we had. When I was a kid, they told us worms surfaced so they wouldn't drown.

But Scientific American writes it’s not so much that, as earthworms can survive several days fully submerged in water. Some scientists think they're coming up to mate. Others say the rain makes vibrations on the soil surface that reminds the worms of predators coming.

Or maybe it’s all about their commute.  

Worms can move greater distances across the soil surface than they can through soil, but normally the surface is too dry. So some experts think that when it rains, worms can speed along up top and stay moist.

Could the worm commute mess up our commute? At England’s University of Central Lancashire Environmental Management, lecturer Dr. Chris Lowe said, "I have not heard of earthworms causing slick conditions, but I can believe it might happen as they exude a mucous through their skin that may cause slippery conditions."

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