Charles Darwin was one of the first scientists to formally study earthworms, which he
called “nature's plough.” Earthworms tunnel through the soil, taking dirt in through their mouths, digesting bacteria and organic material in the soil,
and dumping the leftovers out their other end. Besides letting oxygen and water down into the soil, earthworm droppings or “castings” make good
fertilizer. Fertile soil that has had plenty of compost worked into it will attract earthworms. In return, the worms make the soil even better.
Good soil may have up to 1,000,000 worms per acre.
Earthworms have no eyes, although they can sense light and dark. They don’t have lungs either, but constantly absorb oxygen through
their skin. They need moist soil so that their skin can breathe properly. Worms can sense vibrations and use this sense to try to avoid creatures
such as robins or garter snakes that want to eat them. Earthworms don’t handle cold, so when winter comes they migrate--down.
They tunnel deep into the earth, below the frost line. Sometimes they clump together underground in balls of up to a hundred worms to conserve
moisture. Then, when the soil temperature rises to about 36 degrees F, they come back near the surface and start tunneling again.
Most earthworms are only an inch to a few inches long, but one Australian variety can be 80 cm (32 inches) long, and can stretch to 3 meters
(9 feet) when completely relaxed!
The last Ice Age killed off many North American earthworm species. The most common earthworm in North America today,
the nightcrawler, is an accidental immigrant from Europe, brought along in the soil with potted plants brought by early settlers. Earthworms are
great friends in lawns and gardens, but they can completely change the landscape when they arrive in a new place that had no earthworms before.
When earthworms are introduced to a forest, they start digesting fallen leaves, competing with the other plants and creatures that relied on having
those leaves cover the ground and slowly compost there. Earthworms should be appreciated where they are, but not taken to new places.
For example, never dump left-over earthworms used as fishing bait in a place other than where they were caught. And PLEASE do not dump
any 9 foot earthworms in my yard! That is just too much earthworm for me to appreciate!!!