Data from: Dynamic visual cues induce jaw opening and closing by tiger beetles during pursuit of prey

In dynamic locomotory contexts, visual cues often trigger adaptive behaviour by the viewer, yet studies investigating how animals determine impending collisions typically employ either stationary viewers or objects. Here, we describe a dynamic situation of visually guided prey pursuit in which both impending prey contact and escape elicit observable adaptive behaviours in the pursuer, a predatory beetle. We investigated which visual cues may independently control opening and closing of the beetle's jaws during chases of prey dummies. Jaw opening and closing typically occur when prey is within the 60° binocular field, but not at specific distances, angular sizes or time-to-collision. We show that a sign change in the expansion rate of the target image precedes jaw opening (16 ms) and closing (35 ms), signalling to the beetle that it is gaining on the target or that the target is getting away. We discuss the ‘sloppiness' of such variation in the lag of the behavioural response, especially jaw closing, as an adaptation to uncertainty about target position due to degradation of the target image by motion blur from the fast-running beetle.

在动态运动场景中，视觉线索通常会触发观察者的适应性行为，但现有探究动物如何判定即将发生碰撞的研究，通常仅以静止的观察者或静止的物体作为实验对象。本文描述了一种视觉引导的猎物追击动态场景：在此场景中，猎物即将与捕食者接触以及猎物逃逸，都会使追击者——一种捕食性甲虫——表现出可观测的适应性行为。我们探究了哪些视觉线索可独立控制该甲虫在追击猎物仿真体过程中颚部的开合动作。通常而言，当猎物处于甲虫60°双目视野范围内时，颚部便会开合，但该动作并不对应特定的距离、视角大小或碰撞时间（time-to-collision）。研究表明，目标图像膨胀率的符号变化，会分别提前于颚部开合动作（分别为16毫秒与35毫秒），向甲虫传递其正在逼近目标，或是目标正在远离自身的信号。我们还讨论了行为反应滞后（尤其是颚部闭合的反应滞后）存在此类变异性的现象，将其视作一种针对因高速移动的甲虫产生的运动模糊导致目标图像退化所引发的目标位置不确定性的适应策略。