In this talk, I will discuss a few laboratory experiments that were inspired from examples of biological locomotion.
There, solid structures were forced to interact with their surrounding fluid. These structures, or dynamic boundaries,
interact with fluid in asymmetric fashions - either because of their anisotropic geometry or by the spontaneous breaking of symmetry in their response to the fluid. When subject to reciprocal forcing, the coupled systems behave in ways that can be described as ratchets. The emerging motion of the fluid or structures may help us to better understand many types of locomotion in the biological world.