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DARWIN and his Worms

Charles Darwin, the great English scientist, studied worms for over 30 years. He wrote a book about worms in 1881. The book’s full title is The Formation of Vegetable Mould Through the Action of Worms, With Observations on Their Habits. Most people call it simply “Darwin’s Worm Book.”

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Charles Darwin and his “Worm Book”

Charles and Emma Darwin had ten children. They lived in a big house near London, England with large flower and vegetable gardens. The children enjoyed helping their father with his earthworm experiments. They collected worms from the gardens early in the morning and late at night.

from We Dig Worms! © Kevin McCloskey 2015

You Can Try Darwin’s Experiments!

You’ll need worms! Best bet is to dig earthworms from you own garden. If you can’t do that, ask around. There is probably someone in your neighborhood who has a worm bin with worms known as red wigglers. These worms are about 2 to 3 inches long. Or search for your neighborhood bait shop. If you live anywhere near a lake or river you might find a bait station at your convenience store. A dozen nightcrawlers should cost under $5. Nightcrawlers are likely to be twice as long a red wigglers and so easier to observe.

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Darwin plays piano for the worms. art© Kevin McCloskey 2015

Experiment 1: Can Worms Hear?

Play a musical instrument over your worm habitat. Young Francis Darwin played his bassoon to help his father with this experiment. Another time, Charles Darwin placed a tray of worms on top of his wife’s piano. Emma Darwin had studied piano with the great Frederick Chopin. It is likely she was not amused to see her piano covered with worms. 

So: Can worms hear? Darwin presumed worms could not hear because they have no ears. He noticed the worms sometimes moved when he played certain loud musical notes. What do you think this means? Darwin wrote that worms cannot truly hear, but they sense the vibration of sound through their skin.

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Simple Worm Experiments artwork ©Kevin McCloskey 2015

Experiment 2: Do Worms Have a Sense of Taste?

Do worms have favorite foods?  Can worms taste?  Worms eat dirt, but they also eat dead leaves. Darwin figured if worms always chose one sort of leaf that would show worms have a sense of taste. He collected leaves from his cherry tree and a lime tree. He collected cabbage leaves and carrot tops. He put the leaves on top of the dirt in covered pots where he kept worms. He waited 22 days. Then he looked under the lids to see which leaves the worms like best. Darwin found out worms liked cherry leaves better than lime leaves, but their favorite leaves were carrot tops. 

Try this yourself. You can buy a worm bin or build a simple worm habitat from a soda bottle. Collect leaves and kitchen scraps. You might pick a different sort of food. Do worms like one breakfast cereal more than another?  There were no packaged breakfast cereals in Darwin’s time. This would be a totally new experiment. 

Experiment 3: How Do Worms React to Light?

Do worms like bright light?  What about red light? Lower the lights in the room. Put a worm on a paper plate or other smooth surface. Shine a bright flashlight on the worm. How does it react? Try pointing the light at the front of the worm, then at the back. Is one end of the worm more sensitive to light?

In Darwin’s time there were no flashlights. He and his children went out to the gardens at night with lanterns. He covered the lantern with a red film so it cast a reddish light. He found the worms did not race away from red light. Today fishermen use red flashlights when hunting for worms. You might find some red plastic to put over your flashlight. Try shining red or other colored light on the worms. Are your results the same as Darwin’s?

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TAKE CARE WHEN YOU RETIRE YOUR WORMS. art © 2021 Kevin McCloskey

Important note. Worms are living creatures and deserve to be treated with respect. After your experiments, be careful where you retire your worms. If they came from a compost pile, that’s where they should return. Your bait shop might accept returns. Never release worms into a forest! While worms can be beneficial for lawns and gardens, they are not good for the forest floor. Young hardwood trees have trouble taking root if there are worms in the soil. A number of states have strict rules against releasing worms into the woods. The Minnesota Department of Natural Resources has good info here.

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Poster from the Minnesota Dept. of Natural Resources

Links to more info on Darwin and worms:

Earthworms and Charles Darwin at Darwin Online

The entire text of Darwin’s Earthworms 1881, is free at Project Gutenberg.

http://www.gutenberg.org/files/2355/2355-h/2355-h.htm

More worm experiments suitable for children can be found in Earthworms: Dirt & Rotten Leaves by Molly McLoughlin, Athenaeum, 1986.

Darwin’s Earthworm Experiments, Joe Palco, All Things Considered, NPR

The Amazing World of Earthworms in the UK, BBC, 2012, Emma Sherlock of the Natural History Museum, London, shares her love of worms.

We Dig Worm Race. 2015, 2 minutes, Librarian Patt McCloskey and children demonstrate a worm race on the sidewalk in Kutztown, PA.

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Now for something silly….

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My July, 2020 Cartoonist’s Diary at The Comic’s Journal site, TCJ.com, was a hit. That story was meant for grown-ups, but it is kid-friendly. This origin story of We Dig Worms! is meant for kids, but is adult-friendly. We Dig Worms! was published in 2015 and is now available in paperback. Or, Do me a favor – Ask for it at your library!

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©Kevin McCloskey 2020

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