Elastohydrodynamic Origins of Flagellar Beat Transitions in Sperm

Sperm propel themselves by beating their ‘tails’ or flagella, exhibiting complex beating patterns that are driven internally by a biological engine. These beating patterns are also affected by environmental factors such as viscosity of the surrounding fluid. It is currently thought that changes in the beating pattern must be a result of the biochemical regulation of the internal engine. Using a combination of mathematical modelling and experimental data analysis, this study has instead shown that beat-pattern changes can be achieved through purely physical mechanisms. This sheds light on the yet-unknown mechanisms that give rise to flagellar beating patterns in sperm.