Mechanics of Locomotion

Among annelids, polychaetes, hence more primitive than the other two groups, show a more complex mode of locomotion. Necessarily, the locomotion in polychaetes is dependent on the antagonistic action of muscles on either side. While the longitudinal muscles of one side of a segment are contracted, those of the opposite side are in a fully stretched or relaxed state. In this type of way, a series of waves can be formed along the whole body of the animal. Polychaetes exhibit various types of locomotion.