Earth worms are credited with improving the soil by aerating it and helping incorporate organic matter through their feces.
After being eliminated during the glaciation period, earthworms were reintroduced to North Americawith the arrival of European settlers in the 18th century. There are now more than 30 species of non-native earthworms in Canada, according to Michael McTavish, a postdoctoral research fellow at the University of Toronto specializing in the ecology of non-native earthworms.
I have been pleased with the increase in earthworms in my garden since adding more compost and leaf litter and notice considerably more worms in the garden compared to worms in my forest plots where I have been experimenting with some additives like biochar.
I have also started using a fork for soil prep rather than a shovel or rototiller since I heard it has better long-term consequences for worms and other soil organisms. I have also been careful to cover up any worms dug up during my digging so they are not going to be food for the birds and other critters.
Most worms brought to the surface were not very active or concerned about returning to their tunnels hence my attempts to at least cover them with mulch or earth. After a significant rain it is common to see some worms on the soil surface which make them easy pickings for the predators.
Earthworms don’t use a nose, mouth or lungs to breathe like we do. Instead they absorb oxygen that is dissolved in the moisture on their skin and from the surrounding environment. Hence too much soil moisture and they head for the surface where they often die if they can’t make it back underground before drying out.
With this background knowledge I was surprised one hot sunny day when a worm suddenly emerged from the ground and within a few seconds was rapidly retreating from where I was making some holes for some new potted plants. I watched him quickly move a couple of feet then returned to my work and did not see how far the worm travelled or how fast it returned underground.
I later did some research to see if all worms can move this fast as this one and live so recklessly on top of the ground. One You Tube video showed an earthworm can move quickly but not as fast as my speedy Olympian.
I also heard an interesting program on the radio about how worms can be encouraged to spend some time on the soil surface. There is a festival in Falmoth England the “Worm Charming Championships” where competitors employ music, poetry, and dancing to entice the creatures out of the earth.
The ground rules are that everyone gets a three-by-three metre plot of grass in a field. And they have half an hour to get as many worms out of the ground as possible using vibrations only. And they’re not allowed to use any sort of mechanical vibrations and no digging is allowed.
This year’s winner attracted 20 worms to the surface in just 30 minutes.
An earthworm moves by using two different sets of muscles. Circular muscles loop around each segment, and longitudinal muscles run along the length of the body. When the circular muscles contract, the earthworm stretches, becoming longer and thinner.
The earthworm uses its setae (short retractable projections) to anchor the front of its body in the soil. Now the longitudinal muscles contract and the earthworm becomes shorter and wider or it bends from one side to the other, pulling the body forward.
The earthworm withdraws the front setae and uses its rear setae to anchor itself at the back. The earthworm uses its circular muscles to lengthen and push itself forward again.
Many introduced species can often thrive in a new environment but it can be at the expense of the native fauna or flora. When earthworms move into some of our forests, they have the potential to rapidly change these ecosystems by devouring the leaf litter.
They break down plant matter in much the same way as other invertebrates, but they do it much faster. In essence, worms speed up decomposition, which can be a bad thing for ecosystems used to taking it slow. In a future article we will take a closer look at how earthworms might have some negative impacts.
monica.lamb-yorski@wltribune.com
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