Motion in nematodes is because of the contraction and relaxation of the body muscles of nematodes. A nematode is able to extend in a longitudinal direction but the circumference does not expand much. As a result of this longitudinal motion liquid gut contents visco-elastic organs react. The longitudinal somatic muscles shorten and as a result other organs expand. Waves of contraction and relaxation in the muscles of nematode take place and a propulsion is produced. This repeated propulsion cause motion in a nematode.