Agents of disorder: soft and active cells in liquid crystals*

Liquid crystals are anisotropic, viscoelastic fluids which feature orientational order at the molecular scale. A rigid body in a liquid crystal distorts the orientation field, introducing elastic stresses at equilibrium, and generally forcing the formation of topological defects. Soft colloids like red blood cells, however, can 'share the strain' by deforming into spindle-like shapes. Certain biofluids, mucus for instance, also have orientational order, which can affect the transport of swimming bacteria in other peculiar ways. We will discuss experiments, numerics, and theory which examine the fundamental features of cells which seed disorder into anisotropic fluids.