What kind of variation is there in this situation? A rainstorm has just saturated the ground, soaking into all the pores in the soil and filling the ground with water. Although requiring moisture on their skin to survive, earthworms cannot breathe in water and must crawl to the surface and away from the water. In the last 100 years concrete has been introduced into the environment of earthworms. When earthworms crawl onto concrete they die. Predict how the earthworm might evolve as a result of the changing environment.