Fall's Journey South Update: October 22, 1999 Today�s Report Includes: Worm Watch: Challenge Question #4 Down They Go: Worms in Winter Wonderful Worms Calling All Wormologists: Do You Dig Worms? Observing Worms Up Close Inhale! Answer to Challenge Question #3 Get Ready to Track the Earthworm Migration Next Spring! Worm Watch: Challenge Question #4 While other creatures are winging and swimming south as you read this, underground worm activity is also at a peak. Surprised? Fall and spring are a worm's favorite seasons! Dark, cool, and moist. That's how worms like it. Believe it or not, worms are responsible for eating many of the fallen leaves and debris that result from autumn season. They hang around because there's good stuff to eat, and they like the cool temps and moist conditions fall brings. As you look around for worms this fall, see if you can answer Challenge Question #4: "Why do you see worms on sidewalks and driveways after it rains?" (To Respond to this Challenge Question, please follow the instructions at the end of this report.) Photos This Page Courtesy Of: Agriculture and Agri-Food Canada, Southern Crop Protection and Food Research Centre (SCPFRC), 1391 Sandford St., London, Ontario, Canada. Down They Go: Worms in Winter When temperatures drop or soils get too warm or dry, worms know what to do. If it starts getting chilly, many kinds of worms tunnel deep into the soil before it freezes. Worms "migrate" downward, burrowing deeper to get past the frost. Sometimes they dig six feet deep! There they stay in their burrows, prisoners below soil frozen hard as rock and topped by ice and snow. They coil into a slime-coated ball and go into a sleep-like state called estivation, which is similar to hibernation for bears. (The mucous, or slime, keeps the worms from drying out.) Worms will survive in frozen or dry soils by estivation until conditions improve. Not all kinds of earthworms make that downward journey to survive winter. Some kinds of earthworms lay their eggs in cocoons safe in the soil to hatch when conditions are right. Then they settle under leaf litter on top of the soil, where winter's cold makes them freeze and die. Wonderful Worms: Did You Know? Earthworms have no eyes or ears, but they have light-sensitive cells that help them tell the difference between light and darkness. Their bodies are sensitive to vibrations�and worms may "outrun" the shovels of anglers digging worms for fish bait! Worms can be good for gardens and farmland. By tunneling through soil, they bring in oxygen, drain water, and create space for plant roots. At night worms often come to the surface and deposit mounds of castings� small pellet-like piles of organic matter that have passed through the worm�s digestive tract ("worm poop"). Charles Darwin, who was one of the first to tell about the value of earthworms to soil, estimated that the earthworm castings on a average acre could provide 1/5 inch of new surface soil per year. An acre of good garden or farm soil may be home to a million earthworms. Calling All Wormologists: Do You Dig Worms? Would you like to go on a worm hunt? A cool, moist fall day or evening is a great time to look for worms in garden soil, vacant lots, lawns, parks, or pastures. Humid days before rains, or during rain showers are especially good for collecting worms. USDA soil scientist Dr. Dennis Linden tells how to find worms: First, look at the soil surface. Castings--small piles or pellets of soil, often mixed with some plant litter--tell you earthworms are present. Dig a spadeful of soil and sort through it for earthworms. With experience, you may also find cocoons. While you are digging, always watch for evidence of large burrows with "slickened" walls. These may indicate the presence of night crawlers, the larger, deeper-burrowing earthworms. Forest ecologist Cindy Hale gives directions for a second method that will bring many of the deeper burrowing earthworms to the surface. See how many different kinds of worms you can find in a square foot of soil. Then read on for things to observe when you find your worms. To bring up the worms: Measure off a square of soil about one foot on each side. Use string or boards to make boundaries around the area. Dissolve 1/4 cup (about 40 grams) of ground yellow mustard seed (this is mustard powder from the spice section in the grocery store) in one gallon of water. Shake it up well. (Recipe adapted from theSCPFRC) Slowly pour the mustard solution over the soil inside the boundaries. Pour it so it soaks into the soil instead of running off the soil. The worms will start coming up. Don�t worry; while the mustard irritates their skin and makes them escape to the surface, it does not harm the worms. Pick the worms up with a forceps and put them right into a pan of fresh tap water to rinse off the mustard solution. Now you can take them out of the water and use a magnifying glass for a closer look. Observing Worms Up Close Using a magnifying glass, count the rings or segments along the length of a worm's body. These segments help the worm to twist and wiggle forward or backward. Find the head end (it is more pointed and narrow). You can also place the worm on a rough piece of paper and see which direction it travels. The head end usually goes forward first. On the head end of the worm, find the clitellum--a whitish, swollen band that looks like a collar around the worm's middle. Count the segments from the head to the clitellum. Look for the hair-like bristles called setae (say SET tay) around or under the worm's body. Worms use their setae to help crawl and also to grip and anchor themselves firmly in the ground. (That's why you see robins tugging to get worms out of the soil!) Look at the worm's shape. Is it cylindrical or flattened? Look at the top and belly side. A worm turned over will immediately right itself. Notice the worm's color. After you study and compare the worms, place them where they can safely get back into the soil. Inhale! Answer to Challenge Question #3 Last week we asked, "Do frogs breathe underwater? If so, how?" Hats off to Cherokee Hamilton for this answer: "According to The Usborne Living World Encyclopedia. We have found out that frogs (Adult Frogs) have lungs and breathe air. They also take in oxygen through their skins from air and water." Cherokee Hamilton (kellyk@mail.montasd.org) Remember that breathing includes inhaling and exhaling. When a frog does some of its breathing through its skin, that means taking in oxygen from the water around it as well as getting rid of carbon dioxide. The cold water in lakes where frogs spend the winter actually helps their breathing. Cold water holds more oxygen than warm water. A frog is very inactive as it hibernates underwater, and does not need much oxygen. It works just fine for the frog to breathe through its skin in the highly oxygenated, cold water of lakes in winter. However, breathing through the skin doesn't work so well for frogs if the water is warm, as it is in summer. If you scare a frog sitting at the edge of a pond, it takes a big gulp of air as it dives in. The frog is not very active underwater and does not need to breathe very fast. So, once the big gulp of air is used up, the frog continues to breathe through its skin. But before long, the frog will come out for a real breath of air because warm water holds less oxygen. And warm water speeds up the frog�s metabolism so it needs more oxygen. Get Ready to Track the Earthworm Migration Next Spring! In areas where the ground freezes, one sign of spring is the appearance of the first earthworms of the season. This is called a "vertical migration." In his book, NORTH WITH THE SPRING, Edwin Way Teale describes this event. Read his description. Then keep your eyes open for migrating worms. When you see your FIRST earthworms of the season, report them to Journey North as "Signs of Spring." How to Respond to Today's Challenge Question: IMPORTANT: Please answer ONLY ONE question in each e-mail message! 1. Address an e-mail message to: jn-challenge-fall@learner.org 2. In the Subject Line of your message write: Challenge Question #4 3. In the body of the message, answer the Challenge Question. The Next Journey South Update Will Be Posted on November 5, 1999 Copyright 1999 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form