Department of Civil and Environmental Engineering, Technion, Technion City, Haifa 10587, Israel; Department of Marine Geosciences, University of Haifa, Abba Khoushy Ave, Haifa 3498838, Israel; The Inter-university Institute for Marine Sciences, Eilat 8810302, Israel.
Department of Marine Geosciences, University of Haifa, Abba Khoushy Ave, Haifa 3498838, Israel.
Curr Biol. 2024 Sep 9;34(17):4033-4038.e5. doi: 10.1016/j.cub.2024.07.038. Epub 2024 Aug 5.
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 modulated by distinctly directional swimming patterns that are oriented away from the coast and against the direction of surface gravity waves. Taking a Lagrangian viewpoint from drone videos that allows the tracking of multiple adjacent jellyfish, and focusing on 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.
水母对全球海洋和沿海环境有着深远的影响，因此具有重要的科学、经济和公共利益。水母爆发和扩散的可预测性受到我们对其运动理解的根本差距的限制。尽管有证据表明水母可能会主动影响它们的位置，但主动游泳在控制水母运动中的作用以及水母游泳行为的特征，还没有得到很好的理解。因此，水母通常被认为是被动漂移或随机移动的生物体，无论是在概念上还是在过程研究中。在这里，我们表明水母的运动是由明显的定向游泳模式调节的，这些模式的方向是远离海岸，与表面重力波的方向相反。从允许跟踪多个相邻水母的无人机视频中采取拉格朗日观点，并以钵水母 Rhopilema nomadica 为模型生物，我们表明单个水母的行为转化为整个聚集物的同步定向游泳。数值模拟表明，这种逆波游泳行为导致偏向相关的随机游动模式，从而降低搁浅的风险，因此为水母的生存提供了至关重要的适应优势。我们的研究结果强调了主动游泳在调节水母运动中的重要性，并为在模型研究中更准确地表示打开了道路，从而提高了水母爆发及其扩散的可预测性，并有助于我们减轻它们对沿海基础设施和人口可能产生的影响的能力。
