When it rains a lot, why do earthworms come crawling out from underground?

7/1/1994

By Ranger Rick

Earthworms don't have lungs for breathing. Instead, they take in oxygen through their thin, moist skin. In their underground burrows, they get oxygen from the air found between loose bits of soil.

But when it rains, these air spaces fill up with water. Earthworms can still get some oxygen from the water. But this oxygen soon runs out. So the earthworms crawl up above ground. There they get fresh air while they wait for their burrows to dry out.

What's their hurry to get back in the soil? Life above ground can be dangerous for earthworms. They may dry out, get stepped on, or be nabbed by a bird.