Crawling in Ranks

Nightcrawlers. The name is creepy enough, and surely spookier than the more common name, earthworm. ‘Nightcrawler’ comes from their habit of feeding above ground at night, but most of the time we expect to see them on a fishing hook or nosing through soil under the house. There are more than a thousand different kinds of earthworms worldwide, some of them growing to three feet in length. Probably to the relief of most people, common earthworms, especially the North America variety are just a few inches long, but nightcrawlers do claim the title of largest of North American earthworms and may grow to eight inches long. A few have been found to reach a whopping fourteen inches, weighing almost half an ounce. Earthworms do burrow deeply, but generally stay close to the surface, which is why we sometimes run across one when gardening or playing in the dirt.

During a heavy downpour yesterday, on the way out to the car to get something I found myself confronted by a near invasion of earthworms crawling in ranks across the covered walkway outside my door. My first thought was “Whoa! What the hell and where are they going?” I could see them slithering up out of the grass at the edge of the walkway as though desperate to get out of the sopping ground, but since there was nowhere for them to go, I couldn’t see their purpose. As it happens, rather than being flooded out of the ground and their tunnels, on rainy days earthworms seek out new homes and extra moisture. But what would encourage them to strike out across an expanse of clean concrete heading for a dead end wall?

Maybe not the most dependable of research, but students at one Florida elementary school found that European settlers brought nightcrawlers to North America, that native earthworms disappeared long ago. Nightcrawlers live in soil where they dig long tunnels, swallowing and digesting dead organic material as they go. Look and you’ll find them along damp river and stream banks, in the grass of lawns, gardens and parks. Their burrows may be six to eight feet deep, and according to the Florida State University website, as many as seventy nightcrawlers may be present in a square meter of soil. Their most common predators include frogs, turtles and birds.

Nightcrawlers live in large colonies that can grow by several meters a year. An individual may live as long as six years and produce an average of thirty-eight cocoons yearly, each cocoon containing a single egg. Earthworms perform the highly beneficial task of decomposition and aeration of the soil. They break down and assist in the decay of dead plant material that leads to improvement of the topsoil. As they burrow through the soil they mix nutrients, creating a network of tunnels through which air, water and nutrients travel. As they move through layers of soil from deeper soil toward the topsoil they carry minerals and nutrients from the richer bottom soil to the topsoil.

Though simple organisms, nightcrawlers have some interesting features. Their bodies are made up of approximately sixty percent protein; they have both male and female reproductive organs; they can regenerate a severed body part, though will die if cut in half; they breathe through their skin, and therefore must stay moist to aid breathing. When you examine a nightcrawler up close you see a reddish gray color and ring-shaped segments called annuli. Tiny bristles called setae cover each annuli. Nightcrawlers use the setae to slither and move, as well as burrow into the ground. Like all invertebrates a worm lacks a backbone. The first segment of the nightcrawler’s body contains the mouth. The fact that they eat decomposed plants for energy makes them herbivores. They will eat almost anything organic, but are not fond of citrus. In a single day a worm can eat up to a third of its body weight.

Obviously, nightcrawlers provide a valuable service to the earth, to gardeners and to farmers. Nasty, slimy looking creatures, but the advantages they bring are many. Scream, jump on a chair or run away, but keep in mind the part they play in keeping the earth rich and green. Charles Darwin said about them: ‘It may be doubted whether there are many other animals which have played a part in the history of the world, as have these lowly organized creatures.’