Edward Mills Purcell stated this theorem in his 1977 paper Life at Low Reynolds Number explaining physical principles of aquatic locomotion. The theorem is named for the motion of a scallop which opens and closes a simple hinge during one period. Such motion is not sufficient to create migration at low Reynolds numbers. The scallop is an example of a body with one degree of freedom to use for motion. Bodies with a single degree of freedom deform in a reciprocal manner and subsequently, bodies with one degree of freedom do not achieve locomotion in a highly viscous environment.