Universality in peristaltic locomotion: Linking biology, theory, and simulation.

Inertial jet-propelled swimmers, such as squids, jellyfishes, and salps, swim through rhythmic body contractions, offering an optimized propulsion mechanism that enables sustained locomotion at low energetic cost. Among the different strategies, the peristaltic propulsion is poorly understood, and a unified view accounting for experimental observations is still missing. This study aims to unveil the fundamental principle behind this type of locomotion, proposing a model swimmer, inspired by salps, that mimics the muscle contractions of real aquatic organisms. Numerical simulations reveal the universality of peristaltic locomotion and allow us to explain experimental data and reconcile biological observations. On the basis of these findings, we develop a simple theoretical framework to predict the system dynamics across different geometric configurations. Beyond its biological relevance, this work shows how the principles of fluid-structure interaction can be translated into predictive models, bridging the gap between the foundations of aquatic jet propulsion and physical laws.