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Earthworm Castles

worm graphic

Want to watch an earth-moving, dirt munching, soil making machine? You can watch one live, and in the comfort of your own home. This machine has no gears or wheels. In fact, it's not a machine at all -- it's an earthworm.

"All fertile areas of the planet have at least once passed through the bodies of earthworms."

Earthworms eat their way through the soil, getting food from small pieces of decaying plants and animals. By doing this, they make the soil a better place for plants to grow. Their tunnels let air into the ground and keep the soil loose. The soil they can't digest is excreted with mucus to form the tunnel walls or is left in the form of castings on the surface. In doing their job, worms become important recyclers.

Wacky Worm Antics

Earthworms are simple animals. Inside, they have two tubes, one inside the other. The inner tube is the digestive system which you can see from the outside as a dark line inside the worm. The black color is actually the food in the digestive tract. You'll also notice that worms are segmented where each segment is the same except for the head and a larger band called the clitellum. The head is the end which moves forward and has a mouth but no eyes since worms are always underground in the darkness. The clitellum (or band) that you see contains many glands which secrete mucus to make the walls of a cocoon in which fertilized eggs are deposited. The cocoon is then left to hatch in the soil. Earthworms have both male and female reproductive organs and can produce eggs as well as fertilize them.

Of course earthworms don't need legs, they wriggle by moving their front-half forward, anchor it with small hair-like structures called setae, then they pull their back half forward. Earthworms dig tunnels by eating up the soil in front of them. The soil is then excreted with mucus to form burrow walls. Castings, which are excreted wastes and dirt clumps, show up on the surface of the ground. They look like tiny bunches of grapes. You've probably seen them in wet moist places. If not, go out and try to find a bunch. Castings help fertilize the ground.

That's worms in a nutshell, rather, in the ground. Here's how you can watch them make better soil right in front of your eyes.

What You Need

magnifying glass
large jar (ex. = a used mayonnaise jar)
pebbles
soil
peat moss
worm food (grass cuttings, tiny table scraps, egg shells, coffee grounds, etc.)
black paper
shovel(s) or spoon(s)

What to Do:

  1. Go out and find a cool, moist location. This might be a wooded area under a tree that is also in a low spot, or in a shaded part of a lawn after a good rain. Also look for the castings which mark the best spot to dig. Now, dig a hole with your shovel until you find a worm magnifying glass (get permission first if it's not your land). Use a magnifying glass and observe the worm. Locate the setae and the clitellum. Can you tell the front part from the rear. Put some "worm food" (see #3 below) near the worm's mouth and see if it will eat.
  2. Now, you are going to create a castle for the worm. Find a jar about the size of a large mayonnaise jar. Place a few pebbles in the bottom. Add a mixture of soil and peat moss (if available) to a depth of about 10 cm (4 inches). Invite one or two worms into this new home by carefully placing it/them in the jar.
  3. Place some worm food on top of the soil. Foods that work well are: apple and banana peels, cantaloupe, watermelon, celery, coffee grounds, eggshells, onion peels, pizza crusts and tea bags. (To avoid fruit flies, completely cover the food with a thin layer of soil.)
  4. Keep the castle moist, but not wet.
  5. Cover the jar with black paper. Worms are sensitive to light since they live underground most of the time.
  6. Observe the tunnels that the worm will make. Also look at the castings and the worm's eating habits. Remember to continue to keep the soil moist, keep the jar covered with the dark paper when you aren't watching the worm, and add new "worm food" every few days.
  7. You may want to feed the worm some of your table scraps. This way some of nature's recyclers are helping recycle some of your waste. Composting uses these same principles and helps recycle human food scraps as well as nature's waste.
  8. When you are finished observing your worm, return it/them to the same place you found it/them.

More ideas

  • If you liked this activity and want to expand your worm empire, try composting with worms in your classroom or at home to get rid of more food waste.
  • Make an "earthworm-track observation spot." Pour water over some soil outdoors to make it muddy. Come back the next day and look for worm tracks. Worms need air to breathe. They come out of the ground so they do not drown.

    • Gather worms and go fishing!
    • Take a friend and look for castings after a rainfall.
    • Make an earthworm castle and show it to friends and family.
    • Go on a hike and look for other nature's recyclers like the mushroom.


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