How Do Worms Dig Their Holes?
An earthworm digs a hole by pushing into the loose soil with its pointed head end. The front end then thickens, forcing the soil apart. More of the worm’s body enters the hole until all of it disappears. An earthworm can stretch itself out to become long and thin or pull itself in to become short and fat.
This is because its body has many narrow rings joined together by a softer material that enables it to change shape. Where the soil is too hard to be pushed aside, the worm eats its way through. The burrows it makes are about as thick as a pencil and lined with particles of soil glued together by sticky substances given off by the worm. Worms have tiny bristles, made of a hard substance called chitin, that help them to move and to cling on to the sides of the burrow.
To survive freezing cold temperatures, worms must burrow to an area below the frost line wherever they live. Night crawlers, for example, can burrow to depths of six feet or more. When they burrow down below the frost line, they nest in small chambers at the bottom of the tunnels they dig. Since worms can’t breathe if their skin dries out, they coat the sides of their nesting chambers with slimy mucus to keep them moist through the winter.
Once worms burrow far enough underground, the soil stays at a fairly constant temperature that keeps the worms warm through the winter. This warmer soil down deep acts like a warm blanket and insulates the worms from the cold.
Night crawlers don’t really hibernate like some animals do in the winter. If there is a warm spell during the winter, night crawlers will occasionally come back up to the surface for a while until it gets cold again. When spring returns, worms make their way back to the surface.