The body of an earthworm is made up of many rings joined end to end. An earthworm does not have bones. It has muscles that help to extend and shorten the body. During movement, the earthworm first extends the front part of the body, keeping the rear portion fixed to the ground. Then it fixes the front end and releases the rear end. It then shortens the body and pulls the rear end forward. This makes it move forward by a small distance. Repeating such muscle expansions and contractions, the earthworm moves through the soil. Also, the body secretes a slimy substance to help with the movement.