Last weekend was comparatively warm and despite rain showers, I took the opportunity to get out and clean up debris tossed about by the storms we’ve seen this winter. I wasn’t the only one about, and I found myself leaning on my tip bag watching an enormous earthworm cruising across the moist, mossy lawn post-haste.
Its size caught my eye. When it stretched out it was every bit of 5 inches, retracting to about 4” in its “push-pull” way of gliding along. I grabbed my camera. Its segments expanded and contracted as it moved. Or perhaps we can say it moved because it expanded and contracted, using the four tiny sets of bristles on the outside bottom of each of its segments for traction. These bristles, or setae, also help it in burrowing into the ground, where it’s better protected from predators like birds. Earthworms and 2 other classes of worms are in the Phylum Annelida, classified together due to their prominent segments. Annelida means “little rings”.
When it reached the stone edging, it slowed to “whiff” a rotting leaf from the now completely mushy and dormant Aralia californica (why use the Latin name exclusively for a plant whose common name is as tremendous as spikenard). The glistening, lively worm moved its head about, poking into the leaf; obviously reading sophisticated chemical signals about the nature of what was almost slime. It was a blast to watch something I had never taken the time to observe before: one of nature’s “shredders” in action.
The worm began to munch down in earnest. Fascinating really, that these invertebrates, as well as many others like ground beetles, slugs and snails, service our plants and soil by recycling such detritus into nutrients available for other forms of life in what is called the soil food web. The soil food web is made up of all the organisms that spend all or part of their lives in the soil. If it weren’t for these decomposers, researchers say, we’d be up to our knees, or necks in dead plants and animals.
Some of the benefits of earthworms: making debris more easily digestible for other organisms; turning the soil and improving it’s porosity, fertility and its capacity for holding water; moving organic matter through the soil; stimulating microbial activity by leaving behind nutrient rich feces, or casts, inoculated with microorganisms that live in their intestines; leaving behind burrows that serve as channels for plant roots to easily colonize. In other words, earthworms are invaluable!
For more information on earthworms and the soil food web:
Teaming with Microbes: the Organic Gardener’s Guide to the Soil Food Web, Revised Edition. Jeff Lowenfels and Wayne Lewis, 2010. Timber Press, 220 pages.
Soil Biology Primer [online]. Available: soils.usda.gov/sqi/concepts/soil_biology/biology.html . Soil and Water Conservation Society (SWCS). 2000. Soil Biology Primer. Rev. ed. Ankeny, Iowa: Soil and Water Conservation Society.
© Colleen Miko, 2011