Why do earth worms come out on the pavement when it rains?
Worms cannot survive with out wet skins so the rain offers them an opportunity to travel quickly, easily, to seek out mates in spring, or new territory at other times. Richard Wahl of Shippensburg University in Pennsylvania writes: “Worms of all kinds are highly susceptible to dessication [drying out]. They breed when it rains. They come out of the ground to find each other and to lie side by side in a mating posture, a difficult thing to do in the confines of their burrows. The only time earthworms can safely come to the surface to breed is when the ground is thoroughly soaked.” A worm’s slow metabolism and ability to acquire dissolved oxygen from the water through their skin allow them to survive long periods submerged. They do not have lungs but take up oxygen across their skin in the moist soil they live in. If their skin dries, then it can no longer take oxygen up.
