Ballistic high powered spider webs overcome dangerous prey defenses

Spiders exhibit a remarkable range of silk-based predatory tactics, but usually avoid capturing ants since they are highly defended. Here we report on a spider that exclusively hunts aggressive Oecophylla ants by isolating and immobilising individual workers using a extraordinary ballistic snare that lures ants, then propels them into its core web at extreme speed. By serial arrangements of tension lines, small pre-strains of the silk are sufficient to reach power densities of up to two megawatts per kilogram actuator mass, which surpasses the performance of other natural spring-actuated systems. Thus, the ultimate prey specialisation in these spiders has led to the evolution of extreme web performance.蜘蛛演化出了多样的基于蛛丝的捕食策略，但通常会规避拥有强效防御机制的蚂蚁这类猎物。本研究报道了一种专性捕食攻击性织叶蚁（Oecophylla）的蜘蛛：该蜘蛛借助一套特殊的弹道式诱捕装置（ballistic snare）来隔离并制服单个工蚁，该装置可诱捕蚂蚁并以极高速度将其弹射至核心蛛网中。通过张力丝线的串联排布，蛛丝仅需施加较小的预应变即可实现高达2兆瓦每千克驱动装置质量的功率密度，这一性能超越了其他天然弹簧驱动系统。由此可见，这类蜘蛛的极致猎物特化，推动了其蛛网性能的极端演化。