Shavit, U. | Search bioRxiv

bioRxiv2025

The effect of surface properties on the interactions of particles and marine mucous filters

Free-living suspended cells form the foundation of marine food webs, making suspension feeding a key mode in aquatic ecosystems. Suspension feeders across phyla use diverse filtration mechanisms, often relying on mucus and low-pressure pumps with high filtration efficiencies and self-cleaning capabilities. Traditionally, particle capture was thought to depend on size alone, but recent evidence highlights the importance of physicochemical surface interactions between prey cells and filtration apparatuses. In this study, we investigated the capture of 0.3-3 {micro}m particles by ascidians and found that coating particles with amphiphilic polymers altered their mobility within the mucous filter, affecting capture efficiency. Surface interactions, such as steric repulsion, significantly influence particle mobility and inversely correlate with capture success. Furthermore, we discovered that the mucous filter in ascidians is much thicker ([~]5 {micro}m) than previously believed, functioning as a continuous sheet. These findings suggest a need to reevaluate suspension feeding models, with implications for marine ecosystems and filtration technology development.

systems biology↗

bioRxiv2024

Directional swimming patterns in jellyfish aggregations

Having a profound influence on marine and coastal environments worldwide, jellyfish hold significant scientific, economic, and public interest. The predictability of outbreaks and dispersion of jellyfish is limited by a fundamental gap in our understanding of their movement. Although there is evidence that jellyfish may actively affect their position, the role of active swimming in controlling jellyfish movement, and the characteristics of jellyfish swimming behavior, are not well understood. Consequently, jellyfish are often regarded as passively drifting or randomly moving organisms, both conceptually and in process studies. Here we show that the movement of jellyfish is controlled by distinctly directional swimming patterns, which are oriented against the direction of surface gravity waves. Taking a Lagrangian viewpoint from drone videos that allows the tracking of multiple adjacent jellyfish, and focusing the scyphozoan jellyfish Rhopilema nomadica as a model organism, we show that the behavior of individual jellyfish translates into a synchronized directional swimming of the aggregation as a whole. Numerical simulations show that this counter-wave swimming behavior results in biased correlated random-walk movement patterns that reduce the risk of stranding, thus providing jellyfish with an adaptive advantage critical to their survival. Our results emphasize the importance of active swimming in regulating jellyfish movement, and open the way for a more accurate representation in model studies, thus improving the predictability of jellyfish outbreaks and their dispersion, and contributing to our ability to mitigate their possible impact on coastal infrastructure and populations.

ecology↗