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.”

Charles and Emma Darwin had ten children. They lived near 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.

You can recreate many of Darwin’s worm 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.

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.

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 from his cherry tree and a lime tree. He collected cabbage leaves and carrot tops. He put the leaves on the 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. 

You caN 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. Sometimes he covered the lantern with a red film so it cast reddish light. He found the worms did not race away from the 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 light on the worms. Are your results the same as Darwin’s?

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 go. Your bait shop might accept returns. Never release the 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 rules against releasing worms into the woods. The Minnesota Department of Natural Resources has good info here.