Data from: Young giant water bug nymphs prefer larger prey: changes in foraging behavior with nymphal growth in Kirkaldyia deyrolli

Raptorial characteristics may evolve in predators because of their importance in obtaining food. The giant water bug, Kirkaldyia deyrolli, possesses a claw on the terminal segment of the raptorial foreleg that is crucial for capturing prey. Claw curvature has been previously shown to change during growth in this species, but the adaptive significance of this change has not yet been explored. Predation experiments have demonstrated that young nymphs with highly curved claws caught proportionally larger prey than older nymphs with less-curved claws. Catching behaviours for a certain prey size differed significantly between young and older nymphs. The observation that nymphal growth affects prey-catching behaviour in the giant water bug supports the hypothesis that predators can change catching behaviours based on changes in raptorial characteristics in order to maximize prey resources acquired at each developmental stage.

捕食者的攫捕特征（raptorial characteristics）可能会发生演化，这是因为这类特征在获取食物的过程中至关重要。大田鳖（Kirkaldyia deyrolli）的攫捕式前足（raptorial foreleg）末节生有爪结构，这一结构对其捕食猎物至关重要。此前已有研究表明，该物种在生长过程中爪的弯曲度会发生变化，但这种变化的适应性意义尚未得到探索。捕食实验结果显示，爪弯曲度较高的低龄若虫（nymph）相较于爪弯曲度较低的高龄若虫，能按比例捕获更大体型的猎物。针对特定体型猎物的捕食行为，在低龄若虫与高龄若虫之间存在显著差异。大田鳖若虫的生长会影响其捕食行为这一观测结果，支持了如下假说：捕食者可根据自身攫捕特征的变化调整捕食行为，从而在各发育阶段最大化获取猎物资源。