Doing more with less: The flagellar end piece enhances the propulsive effectiveness of human spermatozoa

Sperm have evolved to perform a difficult but crucial task, swimming thousands of times their body length to the egg through highly viscous fluids. This is achieved through their beating tail, a beautiful structure consisting of sliding filaments, powered by the action of motor proteins. Scientists have spent decades studying sperm propulsion but have tended to ignore the end piece of the tail, characterizing it as a ``ragged end'' with no motor activity. Mathematical modeling shows that the end piece helps the sperm to perform a faster and more efficient swimming stroke.