Earthworms Drying Up on the Sidewalks
You may have seen earthworms shriveling up on the sidewalk in the morning. Over irrigation may be the cause but not for the reason you think. Earthworms breathe through their skin; they do not have lungs like spiders and us or spiracles like insects. As long as there is a reasonably high level of oxygen in the air or water and their skin stays moist, they do not want for oxygen.
Worm experts say that worms do NOT surface to avoid drowning. In fact, they come to the surface during rains (or heavy irrigation) so they can move overland. The temporarily wet conditions give worms a chance to move safely to new places. After rain or during high humidity (irrigation) are safe times for worms to move around without dehydrating. Earthworms can survive for several weeks under water, providing there is sufficient oxygen in the water to support them. Those that find themselves in puddles on sidewalks are marooned and doomed to death by ultraviolet light. A few hours of exposure to ultraviolet light will kill earthworms as will their skin drying out.