Data from: Uncovering changes in spider orb-web topology due to aerodynamic effects

An orb-weaving spider's likelihood of survival is influenced by its ability to retain prey with minimum damage to its web and at the lowest manufacturing cost. This set of requirements has forced the spider silk to evolve towards extreme strength and ductility to a degree that is rare among materials. Previous studies reveal that the performance of the web upon impact may not be based on the mechanical properties of silk alone, aerodynamic drag could play a role in the dissipation of the prey's energy. Here, we present a thorough analysis of the effect of the aerodynamic drag on wind load and prey impact. The hypothesis considered by previous authors for the evaluation of the drag force per unit length of thread has been revisited according to well-established principles of fluid mechanics, highlighting the functional dependence on thread diameter that was formerly ignored. Theoretical analysis and finite-element simulations permitted us to identify air drag as a relevant factor in reducing deterioration of the orb web, and to reveal how the spider can take greater—and not negligible—advantage of drag dissipation. The study shows the beneficial air drag effects of building smaller and less dense webs under wind load, and larger and denser webs under prey impact loads. In essence, it points out why the aerodynamics need to be considered as an additional driving force in the evolution of silk threads and orb webs.圆网蛛（orb-weaving spider）的生存概率，取决于其以最小蛛网损伤、最低制造成本留住猎物的能力。这类生存需求促使蜘蛛丝演化出极强的强度与延展性，其性能在各类材料中极为罕见。既往研究表明，蛛网受冲击时的性能或许并非仅由蛛丝的力学特性决定，空气动力学阻力（aerodynamic drag）可能在猎物动能的消散过程中发挥作用。本研究对空气动力学阻力在风荷载与猎物冲击中的作用展开了全面分析。研究团队依据成熟的流体力学原理，重新审视了前人用于评估蛛丝单位长度阻力的假设，明确了此前被忽略的、蛛丝直径对阻力的函数依赖关系。通过理论分析与有限元（finite-element）模拟，本研究确认空气阻力是减缓蛛网破损的关键因素之一，并揭示了蜘蛛可从阻力消散中获取显著且不可忽视的收益。研究表明，在风荷载下搭建更小、更稀疏的蛛网，以及在猎物冲击荷载下搭建更大、更致密的蛛网，均能从空气阻力中获益。简言之，本研究阐明了为何需将空气动力学视作蛛丝与圆网演化的额外驱动力。