Why do earthworms come to the surface after a heavy rain?

An earthworm breathes oxygen by absorbing it through its moist skin. It likes damp soil, but if the rain is very heavy, the oxygen in the water-logged soil may run out. Then the worm has to come up into the air to breathe. On top of the wet ground, the worm can breathe and wriggle along.

a chain link fence because there so tiny even my albino donkey can't get out