National Taichung First Senior High School, Taichung 40403, Taiwan.
J R Soc Interface. 2013 Aug 7;10(87):20130572. doi: 10.1098/rsif.2013.0572. Print 2013 Oct 6.
Salticids are diurnal hunters known for acute vision, remarkable predatory strategies and jumping ability. Like other jumpers, they strive for stability and smooth landings. Instead of using inertia from swinging appendages or aerodynamic forces by flapping wings as in other organisms, we show that salticids use a different mechanism for in-air stability by using dragline silk, which was previously believed to function solely as a safety line. Analyses from high-speed images of jumps by the salticid Hasarius adansoni demonstrate that despite being subject to rearward pitch at take-off, spiders with dragline silk can change body orientation in the air. Instantaneous drag and silk forces calculated from kinematic data further suggest a comparable contribution to deceleration and energy dissipation, and reveal that adjustments by the spider to the silk force can reverse its body pitch for a predictable and optimal landing. Without silk, upright-landing spiders would slip or even tumble, deferring completion of landing. Thus, for salticids, dragline silk is critical for dynamic stability and prey-capture efficiency. The dynamic functioning of dragline silk revealed in this study can advance the understanding of silk's physiological control over material properties and its significance to spider ecology and evolution, and also provide inspiration for future manoeuvrable robot designs.
跳蛛是昼行性猎手，以敏锐的视力、出色的捕食策略和跳跃能力而闻名。与其他跳跃者一样，它们力求稳定和平稳着陆。与其他生物通过摆动附肢产生的惯性或拍打翅膀产生的空气动力不同，我们表明，跳蛛通过使用拖丝来实现空中稳定性的不同机制，而拖丝以前被认为仅作为安全线起作用。对跳蛛 Hasarius adansoni 跳跃的高速图像的分析表明，尽管在起飞时会向后俯仰，但带有拖丝的蜘蛛在空中可以改变身体的方向。从运动学数据计算得出的瞬时阻力和丝力进一步表明，它们对减速和能量耗散有相当大的贡献，并揭示了蜘蛛对丝力的调整可以使其身体俯仰反转，从而实现可预测和优化的着陆。没有丝，直立着陆的蜘蛛就会滑倒甚至翻滚，无法完成着陆。因此，对于跳蛛来说，拖丝对于动态稳定性和捕食效率至关重要。本研究中揭示的拖丝的动态功能可以增进对丝对材料特性的生理控制及其对蜘蛛生态学和进化的意义的理解，也为未来的可操纵机器人设计提供了灵感。
