for Migrating Earthworms
report the FIRST earthworms of the season as a "Sign of Spring"
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."
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.
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
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?
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
Science Education Standards
- Plan and
conduct a simple investigation.
simple equipment/tools to gather data and extend senses.
- Use data
to conduct a reasonable explanation.
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.