It’s about 7:30 a.m., and I’m walking to class.
There’s a little bit of rain, but that’s okay.
As I progress further down the sidewalk, it sure seems like there are a lot of sticks all over the pavement. As early as it is in the morning, my eyes are not fully awake.
What is supposed to be the sounds of crackling soon becomes the sound of squishing.
Photo by Colten McCabe.
In a state of confusion and utter awe, I realize that what my eyes once thought were sticks, were in fact, earthworms.
Now, with stains on the foxing of my maroon pair of Vans, I wondered, “What has prompted so many earthworms to have a business meeting on the sidewalk?”
I spoke with Todd Rainey, professor of biology, on why earthworms come out in the morning and in the rain.
“Earthworms need to breathe oxygen like we do, but instead of using lungs to do that, they exchange oxygen and waste carbon dioxide across their skin.”
Earthworms need oxygen just like us, and just like us, earthworms also have a hard time breathing in water.
“When they’re down in the burrows in the ground, as long as air can come down those tunnels, they can breathe across their skin and they’re fine, but, when it’s been raining and the tunnels fill up with water, the oxygen can’t come in and the carbon dioxide waste can’t leave the tunnels,” Rainey said. “Basically, they’re asphyxiating (like someone is holding their throat and they can’t breathe for a human), so they come up to the surface to get enough oxygen to keep their bodies going.”
But why is an earthworm always slimy when you touch one?
Todd Rainey, file photo
“Their skin has to be kept moist in order to be able to get enough oxygen into the animal and enough carbon dioxide waste out of the animal,” said Rainey. “They have a slimy layer on their surface, which is fine for protecting them from drying out in the soil, but is less effective when exposed to air outside of the atmosphere in general.”
This ability to stay moist is shown through a chemical that resides within earthworms.
“They have a chemical in their skin that is helpful for the animal, but when that chemical is exposed to sunlight, it is transformed into a chemical that is toxic to the worm,” Rainey said. “Coming out on the surface was fine if it was raining during the night and they needed to breathe, but when the sun comes out after a while, this skin chemical will have been transformed and they will not be able to escape off of the sidewalk surface back into the soil. This is because they have been poisoned or paralyzed by this chemical transformation.”
When it rains, earthworms come out of the soil to get more oxygen and find themselves getting stuck on the pavement.
“When they’re exposed out on the sidewalk, there’s nowhere to go, and if they’re getting sick, they can’t wander off the pavement and into the grass again, so they end up dying as you found when you were looking at the bottoms of the soles of your shoes,” explained Rainey.
After finding out the reason behind why earthworms come upon the sidewalk, I do feel partially bad for assuming that they do it to ruin my shoes.
So, when you’re walking to class, and it’s too early to even keep your eyes open, remember that there are earthworms just trying to survive, much like you and me.
