How do worms move through hard soil, and how far can ants see?

We explore the curious questions that science can answer

If the soil is rich in food, or compact, worms will in effect eat their way to the surface (Getty/iStock)

How do worms penetrate hard soil in summer?

Earthworms are largely crevice burrowers, so they seek cracks in the soil into which they can squeeze. They move through such crevices by peristaltic locomotion, bulges passing backwards along the body acting as temporary points of attachment in propelling the animal forwards. If the soil is rich in food, or compact, they will in effect eat their way along.

In compact soil, much of the material that passes through the worm is deposited as casts on the surface. In less compact soil a large part is deposited underground. During cold or dry weather many species burrow deeply, cease feeding, curl into a ball and wait for warmer or dryer conditions to return.