Earthworms and Rain
Do earthworms come to the surface to utilize the rain for
fertilization of the eggs?
I think that earthworms surface after rain to escape saturation of the soil.
The moiture found within the mucus secreted by the earthworm is used to
facilitate the transfer of sperm between mating earthworms. This is the same
secretion many people find when handling these animals. Rain is not a part of
However, earthworms surface during a heavy or prolong rain because the transfer of
oxygen between their soil environment and their blood stream is greatly reduced
when their surroundings is primarily water. Water holds much less oxygen than
air and earthworms rely on the air in the soil for diffusing adequate oxygen
through their skin. Hence, they come to the surface to increase the oxygen uptake when rain
water saturates the soil and displaces the air in the soil.
Click here to return to the Zoology Archives
Update: June 2012