Squirmin' In the Rain

My first-ever blog. I feel so viral! I was excited when Janet invited the naturalists over here at Holliday Park to join in the fun, but was having a hard time getting inspiration for a post. Then, this morning when I stepped outside, it hit me! Then it hit me again! Right on the head this time! After a few weeks of unseasonably warm and dry weather in central Indiana, we were finally getting a good rainstorm. I donned my raincoat to avoid any more cold drops down the neck, and quickly realized that I was not the only creature enjoying the change in weather. Earthworms were everywhere!

photo from Wildlife Trust

There is a bit of debate as to why earthworms come to the surface during a good rain. Since they ‘breathe’ through permeable skin, some believe that rain causes the ground to become too saturated and that the worms begin to drown.

Others think that it has more to do with the worms taking the opportunity to move quickly in order to colonize new areas (a big risk when you factor in hungry birds like this one found on Google Images, hikers boots, etc.) Another theory is that the carbon dioxide produced from respiration dissolves into the rainwater and creates carbonic acid. The soil gets too acidic and the worms head for the surface.

Regardless of the reason, seeing these little annelids always reminds me of what an important role they play in our world. One study has shown that on the average acre of cultivated land, over 16,000 pounds of soil has passed through the digestive systems of earthworms. The droppings, or castings, are full of minerals that provide the building blocks for a healthy ecosystem. When you factor in the amount of organic material they decompose, the soil they aerate, and the food source they provide for other animals in the ecosystem, it’s no wonder Darwin wrote “It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures.”

I could go on and on about all the other features that make earthworms so fascinating, but the sun is back out, the wigglers have headed underground, and I don’t want to overstay my welcome. But hey, think of it as a good excuse to head out and do a little digging yourself!