Motility and guidance of sea urchin sperm

The sperm tail movement is a direct result from contributions of fluid mechanics, elasticity, and molecular-motor activity. Within the flagellum, the axonemal engine yields overall mechanical response and, ultimately, motility. This chapter attempts to provide a comprehensive and integrative overview of the relationship between the mechanics, signaling of sperm propulsion, and the physiological function of these cells in 3D. Sperm swimming, with its intricate coupling between the regulations of the flagellar beating has to ultimately fulfill its evolutionary function honed in their natural environment, the open sea. The strategies that are being employed to unravel this fascinating and fundamental process are revisited, where the sliding of water bodies shape chemical landscapes sensed by sperms during their journey, affecting motility patterns and directly determining gamete encounter rates.A.G. and C.B. acknowledge grants from the Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica UNAM (PAPIIT/DGAPA) IA202417 to A.G. and IN206016 and IN215519 to C.B. A.G. acknowledge the Consejo Nacional de Ciencia y Tecnologıa (CONACyT, 252213). We thank CONACYT and PAPIIT for fellowships to H.R. I.T. acknowledges the support from the Spanish Ministry of Economy and Competitiveness Grants No. FIS2016-77692-C2-1-P