Interfacial Swimming Mechanics of Cypris Larvae Amphibalanus amphitrite

While some animals are adapted to the air-water interface, others traverse it occasionally for survival. This study examines the interfacial swimming of cypris larval Amphibalanus amphitrite, commonly known as acorn barnacles. These crustaceans, typically submerged, possess hydrophobic bodies that allow attachment to the air-water interface despite being denser than water. To better understand cyprid surface dynamics, we analyzed the swimming mechanics of Amphibalanus amphitrite using DeepLabCut, which provided Cartesian coordinates of cyprid body positions for every frame. This data enabled us to track the trajectories of cyprids swimming on the air-water interface over various timescales, relating velocity distribution to various types of random walks. By integrating these insights with a fluid mechanics model of single-stroke trajectories, we estimated the power exerted by cyprids to swim at the interface. Our findings offer new perspectives on the adaptations and energy expenditure of these organisms in navigating the interfacial environment, shedding light on their unique survival strategies.