Keywords: vortices, locomotion, swimming, flying Abstract: The formation and shedding of fluid vortices is an inevitable consequence of movement for all but the smallest of swimming and flying organisms. Can animals use these vortices to enhance locomotion? If so, can their methods of vortex-enhanced propulsion be translated to engineered systems? This talk will describe experimental studies of jellyfish and numerical simulations of eels that suggest candidate mechanisms to enhance the efficiency and speed of locomotion by using vortices. A bio-inspired underwater vehicle is created to test the ideas in an engineering context. It appears that swimming and flying animals have significant opportunities to optimize their locomotion by making use of vortices.