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Earthworms: Fun activities to help kids learn about worms
Anyone who has done much digging or gardening has seen an earthworm. Many people think they’re wiggly, slimy and disgusting. When you get to know them better, you realize that even though you may not want to pick one up or keep one as a pet, they are an important part of the world we live on.
Earthworms can be found almost anywhere except sandy deserts and areas with permanent frost in the ground.
There is no fossil record of earthworms because their bodies are soft and they have no skeleton. When they die, they quickly decompose.
Most earthworms live about six years. They eat almost anything, mostly decaying vegetable matter in the soil like dead leaves.
Worm Tracks Activity
Have the kids wear old clothing that won’t be ruined if they get paint on it.
1. Cook spaghetti and add some oil to the water so that the noodles do not stick together.
2. Drain and place in a small container for the kids. Wait for the spaghetti to completely cool.
3. Cover the work surface with newspaper or plastic.
- Set out 2-3 plates filled with different colors of washable paint.
- Provide some white paper to paint on.
- Drag a piece of spaghetti through the paint and then across the paper to create interesting designs on the paper.
You may want to do this activity before actually working with real worms. This will help get the kids accustomed to handling wormy things and make them a little less squeamish about holding live worms.
Although you shouldn’t force kids to do things they are uncomfortable doing, they should be encouraged to try new things.
Most of the worms in North America are quite small, usually only a couple of inches long. Some can grow as long as two feet. Their bodies are made up of rounded segments called annuli. These segments are covered with little hairlike bristles called setae. Worms use their setae to help them move and burrow in the soil where they live.
Some of the larger worms are called night crawlers because we usually see them at night when conditions are better for them to crawl to the surface to move around and find food.
They usually live underground, close to the surface. Sometimes they burrow as far down as six feet or more.
How do worms move?
There are two characteristics of worms that make it possible for them to move around. They have very strong muscles for their size and can wiggle like crazy or quickly alternate between being long and slender or thick and stubby.
When they want to move, worms pull their setae into their body, wiggle or expand forward. When they want it to stay still, they push their setae back out and use them like spikes on a pair of track shoes.
When a predator, like a robin or even a person gathering worms for fishing tries to pull a worm from its hole, the worm will push out all its setae and hold on for dear life.
Earthworms don't have eyes, but they do have light-sensitive cells in their skin. Worms can’t see like we do, but they can detect light and changes in light intensity.
On a day that you’ve watered your lawn, wait until dark and take a flashlight out to look for night crawlers. Move slowly across the grass while shining your flashlight ahead of you, looking for worms.
If you see one, pay attention to what it does when you shine the light on it. If it hasn’t crawled completely out of its burrow it will probably scoot back into the hole and hide. What does it do if it is completely out of the ground?
Earthworms have very simple brains which are used mostly to direct body movement in response to light. If an earthworm's brain is removed, changes in its general behavior are hardly noticeable.
Why are earthworms important?
It may not seem like earthworms are very important, but they provide a great service to the earth’s ecosystem.
One important thing that earthworms do is plow the soil by tunneling through it. Their tunnels provide the soil with passage-ways that allow air and water to circulate. This is important because soil microorganisms and plant roots need air and water to grow. Without some kind of plowing, soil becomes compacted, air and water can't circulate in it, and plant roots can't penetrate it.
Turning the soil is an important part of the work worms perform, but they do even more than just move stuff around.
One study showed that each year on an acre of average cultivated land, 16,000 pounds of soil pass through earthworm guts and are deposited on top of the soil.
Earthworm droppings, called castings, are great fertilizer. They are rich in nitrogen, calcium, magnesium, and phosphorus. These are important nutrients for healthy, prospering ecosystems. So, not only do earthworms plow the soil, they fertilize it at the same time.
In 1881, Charles Darwin, a famous scientist, said of earthworms:
“It may be doubted whether there are many other animals which have played so important a part in the history of the world as these lowly creatures.
Without the work of this humble creature, who knows nothing of the benefits he confers upon mankind, agriculture, as we know it, would be very difficult, if not wholly impossible.”
Why do worms come out after a rainstorm?
If you’ve ever gone for a walk after a heavy rain storm you’ve probably seen worms crawling around on lawns, in gardens and even across sidewalks and streets. Many people believe this is because they must get out of the water saturated soil or they’ll drown.
Worms don’t breathe the same way humans do. They get their oxygen through their skin. If they are completely submerged in water they can breathe and survive as long as the water has enough oxygen in it, much in the same way a fish uses its gills to breathe in the water. Studies have proven that worms can live for several days completely under water.
Why do worms come out after a rain? For the same reason they come out at night. Because they want to.
Worms are covered with a slimy coating called mucus that makes it easier to get the oxygen they need through their skin. If they become dry the mucus doesn’t work as well and it becomes harder for them to breathe. At night and after a rain storm the air is cooler and moister, creating an environment that is comfortable for worms. They work their way to the surface looking for food and for other worms to mate with.
When it gets too hot, cold, or dry for worms, they can protect themselves by burrowing deeper into the soil where conditions are more constant. Sometimes they will go as deep as six feet or more. Sometimes they curl into a tight ball and slow down their metabolism. This is called estivation and is similar to hibernation. When conditions get better the worms will resume their normal activities.
If you see a worm squirming across a sidewalk, gently pick it up and move it to a safer place such as a patch of shaded soil or a lawn.
Earthworms might seem to be a little creepy, but they can’t hurt you. After you’ve rescued your worms, wash your hands to get the mucus off.
What do earthworms eat?
Earthworms eat dirt. The nutrition they need to grow and survive comes from the tiny things in the soil. Things like decaying roots, leaves and decomposing animal remains. Animal droppings are an important source of food for earthworms because they are rich in decaying organic matter.
Worms are sometimes described as a tube within a tube. This is because they are a very simple organism. They are made up almost entirely of a digestive system inside a muscular tube shaped body.
Worms eat by pulling soil into their mouth, which is basically a hole at the front of their body. The dirt passes through the pharynx and esophagus into the crop and the gizzard where it is digested and all of the nutrients are removed. What is left over passes through the intestine and out the anus.
Worm poop is called castings. These castings are deposited wherever the worm travels and helps fertilize the soil.
Earthworms are the ultimate valentine
Earth worms are different from people in a lot of ways. One difference is that worms have five hearts.
If you put a worm on a clear glass dish and hold it above your head you can see through the light underside of its body. Can you see the five hearts? Can you see the blood moving through the veins? How fast do the hearts beat compared to your own?
Make a Dirty Snack
Here’s a fun snack to help kids remember that although eating dirt seems pretty gross, just because something looks unappetizing doesn’t mean it can’t taste good.
Ingredients: (for each person)
1/2 cup (4 oz.) chocolate pudding
1/4 cup chocolate cookie crumbs
6 gummy worms
Fill cup with chocolate pudding. Crumble chocolate cookies and sprinkle on top of the pudding. Garnish with gummy worms.
Although dirt tastes good to worms, remind children that it’s not good food for humans and they shouldn’t really eat dirt.
Earthworms can eat as much as their own body weight every day. If you were a worm, how much dirt pudding would you eat every day?
What to do:
Weigh one of your empty pudding cups and then weigh a full one. The difference will be the weight of the dirt pudding.
Have the kids weight themselves and then divide their weight by the weight of the dirt pudding. The answer will be how many cups of pudding they would eat every day to eat as much as a worm.
Earthworms are great for lawns
Earthworms help our lawns in more ways than one. As they burrow through the soil they mix and loosen the soil and their castings make great fertilizer, but there’s another thing they do that helps make grass healthy and green.
Worm slime is rich in nitrogen and nitrogen is one of the best things for making grass green. Many gardeners add chemical nitrogen to their lawns, but worms do it for free.
Some people believe that if you break or cut a worm in half, they will turn into two new worms. This isn’t true.
Although worms can sometimes regenerate their tails, the rear half will always die if it is separated from the front half. This is because all the vital organs like the heart, mouth, crop, and gizzard are located in the front half of each worm.
The rear half will always die, but the front half may live to become another whole worm. This is called regeneration. The front part must be long enough to contain the clitellum and at least 10 segments behind the clitellum, about half the length of the worm. The new segments grown will be slightly smaller in diameter than the original segments and sometimes a bit lighter in color.
Hands-on worm activity
After you’ve collected or purchased your worms, take a few minutes to touch, hold, and observe them. If you don't want to gather your own worms, almost every community has someone who sells nightcrawlers for fishing. Many sporting goods departments also sell worms.
Here are some things to talk about.
How to handle an earthworm
Some people are squeamish about holding worms. Although they might be slimy and funny looking, they can’t hurt you, but you can hurt them if you’re not careful.
Always hold them gently and try not to squeeze them. The best way to handle them is to slide your fingers under them and lift them from underneath their body. Then you can set them on your open hand and watch them move around.
They will usually squirm around when you pick them up, but they can’t bite or sting, so there’s no danger in holding them. Once you are finished with the worms, you can release them in shady, moist soil. Be sure to wash after you let them go to get the mucus off your hands.
Things to look for as you study your worms
Look for the clitellum. It’s a wide, thick band around the worm about 2/3 of the way back from the head.
How can you tell the head from the tail? Look at the head with a magnifying glass. See if you can find the mouth with its overhanging lip.
Notice that the worm's body is made up of segments. Each segment has two pairs of special bristles (called setae). Wet your fingers and gently run them down the worm's body to feel the rough setae.
Let the worm crawl on your hand or a paper towel. When it wants to move, it becomes long and thin. If you touch it, the worm contracts and becomes thicker.
Find a light-colored worm. Wet its upper surface and use your magnifying glass to observe the upper surface near the head. You might be able to see the worm's five beating hearts.
Dip a cotton swab in alcohol or ammonia. Hold the swab close to the worm's head, but DON'T touch the worm with the swab.
What happens when the swab is near the head? Does the worm move? Hold the swab near the tail, then near the middle. Can the worm detect where the fumes are? How does it react?
Shine a flashlight on the worm and see how it reacts to the light.
Place a paper towel on the table top and moisten half of it with water. Place a worm on the towel and see how it reacts. Did it seem to prefer the dry side or the moist side of the towel?