Earthworms are animals that live for 4-8 years. But why do earthworms come out in the rain? This post will answer that question!
Why do earthworms come out in the rain?
There are 4 different theories about why Earthworms come out in the rain. I will consider them all and tell you which theories are more likely.
- The most likely reason that earthworms come out in the rain is because they begin to drown as the soil becomes wet. Earthworms need a moist environment to survive but if the ground becomes too moist they would begin to drown. Therefore, they head to the surface!
- Another hypothesis is that earthworms find it difficult to move underground. Therefore, they come to the surface when it is moist to start colonizing new areas. They cannot come out in dry conditions as they would dehydrate. They also die when exposed to high levels of UV rays (released by the sun). Moving in the rain would also ensure that they are not eaten by birds.
- Another theory is that the water in the soil becomes too acidic, forcing earthworms to leave. As organisms breath they release carbon dioxide. This reacts with water to form carbonic acid. As many organisms live in the soil, there is a lot of carbonic acid formed. Earthworms cannot survive if the water becomes too acidic.
- The least likely reason that earthworms come out in the rain is that they actually get stranded by the rain and cannot return underground. This hypothesis states that earthworms come to the surface to breed and, if it begins to rain, they become trapped above ground. However, this has been observed rarely for only a few species of earthworms.
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