Have you ever noticed that earthworms surface during a heavy rain? Lets find out why they do that.
Container of earthworms and soil (can be purchased at a bait shop)
One-half cup (125 ml) of aquarium gravel (purchase at a pet store)
Pour water into the cup containing the gravel until the water covers the gravel. Explain why there are bubbles in the water. Why do they quit forming?
Pour water into the container of earthworms and soil until the soil is covered. Did bubbles rise from the soil? How did the earthworms respond to the water?
This Is What Happens:
Bubbles rise for a short time when water is added to gravel or soil. The earthworms rose to the top of the wet soil.
Science Behind It:
The water pushed the air out of the cavities in the gravel and since there are air spaces in the soil the air was replaced by the water in the soil. The bubbles seen were air bubbles and they stopped when all of the air was displaced by the water. The worms surfaced because of the lack of or low level of oxygen in the soil. During heavy rains, worms are often seen on the surface of soil and they are seeking oxygen.