The Dark World of Underground

 When I listen to the news and hear about the distressing things happening all over the world, sometimes I like to zero down into present time right where I am. Worrying about whether we will have a future doesn't seem to help. I worry about how long we can survive if we cut out all our environmental protection and focus on our cultural tendency to make money, buy more things, and ignore the needs of others. It is depressing! Of course it's important for us all to use what influence we have, pitch in at whatever level we can to help the future of our world, join with others in good work. But sometimes I need to just shut out the chaos and focus on Nature. A couple of us from Prairie Hill have enrolled in a 3 1/2 month course: Iowa Master Naturalists. And each Saturday we go to learn about the world around us firsthand. Each week we also bring to class a "Nature Share", something we've noticed and researched during the previous week. And my focus this week was the earthworm. I found one outside my front door burrowing in my flower bed. Then I read all I could find about earthworms.

Ever since I started growing things in the soil, I have loved earthworms. They do so many beneficial things in the cycle of life underneath the ground, improving the soil for us gardeners.  So I celebrate whenever I see an earthworm, especially since I've been having to build up my soil from a stony infertile building site. Earthworms have been on my most-appreciated list. And the whole world of their home, the soil itself, has always been intriguing to me.  There's a tapestry of life under the surface that is unseen, and so easy to forget about. In these dark, mysterious realms of "dirt" under our feet, there live many times more invertebrate organisms than vertebrates on the surface of the world. It is teeming with life. So for my class, I started with one soil resident, earthworms this week, finding out all kinds of fascinating facts about their lives, their bodies, their organs and systems. 

As we probably all know, earthworms break down dead and decaying matter on top of the soil, turning it into rich humus that is good for plant growth. They also aerate the soil with their holes and channels. Did you know that earthworms breathe through their skin? They take in both oxygen and carbon dioxide through the skin, a skin that also helps them sense light and touch since they have no eyes. If that grabs your curiosity, I'd recommend you see what you can find about this unique soil resident on the web. But here are a few interesting facts. Earthworms have five hearts that pump blood through their bodies! To make offspring, they build a cocoon in the soil full of emerging little worms. An earthworm can live for more than 4 years! And they have spines along their skin that help them hold to certain spots. There is much, much more that you can find out about them.

However, one thing I learned was a total surprise. I had always thought earthworms were our friends, blameless for any problems we might encounter. Yet I found that some species of earthworm are not good for certain ecosystems. I did not even want to believe that at first. But now that I know more, I can understand. Just as with life above ground, there are many below-ground life forms that have been imported (most often unknowingly) from other parts of the world. And sometimes these different kinds of worms or beetles or spiders or bugs do not fit well with the ecosystems they "invade". We are more familiar with the issue of plants and trees that are non-native. They sometimes have a tendency to be invasive because they are recent additions to an ecosystem that has already evolved in a balanced way, and these newcomers upset the balance. There are scientists studying the effect of areas where invasive underground invertebrates have negatively changed the growth and health of the above-ground ecosystem. So now I can believe that some earthworms are not good for the place where they have landed. (But, I want to say, it is not their fault!! I think I am prejudiced...)

There are other tiny animals besides earthworms in the soil. As I was weeding my front garden this afternoon, a little bug scurried over my hand. I recognized it, but was unsure what it was called until I looked it up. The Xerces Society has a handbook of invertebrate identification that is really helpful, and this bug was identified as an Isopod. What I found is that it is mostly nocturnal, so I probably bothered it in its resting phase today. They can live over 2 years. Like earthworms, they help to recycle plant material, breaking down the nutrients. Some can roll their bodies into a ball. I think this one I saw could not do that.

The Dung Beetle became famous when some popular nature photographer filmed one pushing a round ball of dung up and down obstacles on its long way home. There are many species of the dung beetle. Many dig tunnels under piles of manure, lay their eggs there, and bring up their young right below their food source. Some actually lay their eggs in the dung itself. Only a few species make the manure into a round ball and roll or pull it to a home further away. The presence of dung beetles helps return nutrients to the soil, and reduces pest and parasite habitat. They can live for more than 3 years.

Then there are Millipedes, those many-legged creatures. As with so many others, their presence in the soil helps with decomposition of plant materials. They are able to excavate deep tunnels, so they are often found many feet below the surface. The females protect the eggs they've laid in a nest underground. And millipedes are long-lived - as long as 11 years!

I've just scratched the surface here, I know. There are probably thousands or millions of different forms of life in our soils. So I ask myself, how can this knowledge help me to take better care of the soil around me? The most obvious thing, I guess, is that herbicides and pesticides are harmful to the whole ecosystem of underground life. We fool ourselves when we think it only affects the plant we are trying to get rid of. Being aware of the forces of decomposition activated by these small creatures is also good to have in my consciousness. And it will perhaps guide me to take better care of my compost pile, making that a more pleasant place for the workers who will turn it into soil. It's a big world out there, and so much that we are still discovering. Who is your favorite underground-dweller?