Watch for Migrating Earthworms
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In areas where the ground freezes, the appearance of the first earthworms coming up from the depths is a sure sign of spring. Theirs is called a vertical migration. In his book, North With the Spring, Edwin Way Teale describes this event. Read his description below, then keep your eyes opened for migrating worms. When you see your FIRST earthworms of the season, report them to Journey North as a "Signs of Spring."
"One morning we followed a path across a wide, dew-covered field. Ahead of us, as far as we could see, the trodden earth was speckled with the castings of innumerable earthworms. They, in their way, recorded a form of vertical migration in the spring. Earthworms, in the fall, migrate deeper into the earth, below the frostline. Sometimes they ball up to reduce moisture loss — as many as a hundred worms being bunched together — and thus spend the winter in inactivity.
When spring comes and frost leaves the soil, the earthworms become migrants again, tunneling upward. They appear at the surface, leaving the first castings of the new seasons, as soon as the average temperatures of the ground reaches about 36 degrees. At the same time, the robins return from the South. This is part of the endlessly meshing gears of nature's machine — the appearance of both earthworm and robins when the thermometer rises to a give point. All over the North, the return of the humble earthworm, the completion of its vertical migration, is a symbol of the arriving spring." (North With the Spring, St. Martin's Press. 1951.)
Activities
- Journaling: How do you think an earthworm senses that spring is here? What does the underground world seem like to a worm? How do you think a worm feels when it reaches the top of the soil and the sun shines on it?
- You Be the Scientist: When the first earthworms emerge in your area, take temperature readings of the soil in places where you see worms and in places where you don't. Try to get a reading right at the soil's surface, and at depths of 3", 6", and 12". Graph your findings. How would you explain your findings? What questions do you have?
National Science Education Standards
- Plan and conduct a simple investigation.
- Employ simple equipment/tools to gather data and extend senses.
- Use data to conduct a reasonable explanation.
- Scientists develop explanations using observations (evidence) and what they already know about the world.
- The behavior of individual organisms is influenced by internal cues (such as hunger) and by external cues (such as a change in the environment).
- An organism's behavior evolves through adaptation to its environment.
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