Earthworms don’t have much of a brain, so
they live by simple rules. One rule is “stay
away from dry.” This is a pretty good rule most of
the time. It keeps them in moist dirt so they
don’t dry out. That’s why you don’t usually see
worms above the dirt. When it rains, their rule
doesn’t keep them underground anymore. If they
go back down into the dirt, they are fine. If they
are on a hard surface, like a sidewalk, they may
be in trouble when the water dries up.
Can you think of any other rules an
earthworm should have to keep it safe?
You may want to study animal behavior.
Thanks for asking,
You have asked a very interesting question
about a phenomena you have probably noticed
yourself! Nice job! You have completed the first
two steps of scientific hypothesis testing:
observations and asking questions about those
The first explanation you might come up with is
that the worms are trying not to die from drowning
in the rain water. But worms cannot drown in
water like we can because worms breathe through
their skin, and need moisture to breathe!
Scientist hypothesize that worms move to the
surface during heavy rains to migrate, or
move from place to place, more effectively. When
worms are living in the dirt, they can't move very
quickly, and need to stay in moist dirt so they
can breathe. So when they have the opportunity to
move, worms take it! You can read more about
earthworms and rain here:
Also, here's a cute cartoon of worms on the move!
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