Why do worms come out when it rains?

Big picture huh?

Its been raining for days where I live and as I was walking to class, I saw those darn earthworms again. I always wondered why this happened for years. Many of you may know this already but hell, I didn’t know. So with that said, here’s what I found….

Researchers hypothesize several reasons why heavy rain storms bring these crawlers out of their soil homes. For years scientists seemed to think the only reason earthworms came to the soil surface after a good rain was to prevent drowning in their water-filled burrows.

As it turn out, contrary to popular belief, worms are not forced out of the ground because their holes will be flooded.Worms breath through a chemical process so they actually can breath in water for days. There are many reasons why worms come out from the ground when it rains but not the typical reasons people think. Sure some of us would assume its because they like the conditions and its easier for them to slither when the ground is wet, but I would not have guessed it was for mating purposes. In fact, one of the reasons worms go above ground is to mate, so many worms are above ground when it rains because they like the conditions, so why not find a mate?

But even so, only certain species of earthworms surface to mate, only a few of the 4,400 existing species do in fact, in turn, making it unlikely that mating is a primary reason for widespread surfacing.

Another explanation involves rain drop vibrations on the soil surface sounding similar to predator vibrations, like that of moles. Earthworms often come to the surface to escape moles.“Rain can set up vibrations on top of the soil like mole vibrations,” said Professor Josef Gorres of the University of Vermont’s Department of Plant and Soil Science. “Similar to how earthworms move upwards and out of the way when predator vibrations are felt, they could move in a similar way for rain vibrations.”

Also, the earthworm’s cuticle (outer layer of skin) must remain moist to absorb oxygen. When they are in soil, they receive oxygen from air trapped underground. Rain-soaked dirt, however, fills that air space with water, and although earthworms can absorb oxygen from the water, air contains more oxygen, so they will surface for more efficient breathing

Your Thoughts?


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