This course deals with life in fluids. Fluids are anything that flows, and nearly all living things inhabit a fluid environment of some sort, either water, air, or a self-created fluid such as mucus. Inhabiting a fluid world means being able to make fluids move, which requires work, which comes out of the creature’s metabolic energy budget. Dealing with fluids means managing inertia and viscosity, and life is almost infinitely ingenious in clever ways of doing that. Physics of Life Fluidsis the third of a four module series in the series Physics of Life. Physics of Life Thermodynamics was the first. Physics of Life Biomechanics was the second. Following Physics of Life Fluids will be Physics of Life Wave Phenomena, which is concerned with sound and light.