How can courtship synchronize the release of eggs and sperm in aquatic animals?

In aquatic animals, courtship plays a vital role in achieving the necessary synchrony for external fertilization, where eggs and sperm are discharged into the surrounding water. Because fertilization in these environments depends on the precise timing of gamete release, courtship serves as a communication system that coordinates the actions of potential mates.1

This synchronization is often achieved through specialized social signals known as displays, which convey information about an individual's readiness to reproduce. For example, in some marine polychaetes, reproductive activity is synchronized with lunar cycles. During these events, the female releases substances or engages in behaviors that stimulate the male to release sperm, which in turn triggers the female to expel her eggs. This process is so highly coordinated that large numbers of individuals release their gametes simultaneously, significantly increasing the likelihood of successful fertilization.12

Beyond simple timing, courtship helps reduce hostility between partners, ensures species recognition to prevent the waste of gametes, and facilitates the physical transfer of sperm in species that utilize spermatophores or other specialized delivery methods.12