Functional Morphology and Biomechanics, Institute of Zoology, Kiel University, Kiel, Germany.
Department of Engineering, Geotechnical Engineering, Aarhus University, Aarhus, Denmark.
J R Soc Interface. 2021 Sep;18(182):20210539. doi: 10.1098/rsif.2021.0539. Epub 2021 Sep 15.
Sandy pitfall traps of antlions are elaborate constructions to capture prey. Antlions exploit the interactions between the particles in their habitat and build a stable trap. This trap is close to the unstable state; prey items will slide towards the centre-where the antlion ambushes-when entering the trap. This is efficient but requires permanent maintenance. According to the present knowledge, antlions throw sand, mainly to cause sandslides towards the centre of the pit. We hypothesized that: (i) sand-throwing causes sandslides towards the centre of the pit and (ii) sand-throwing constantly maintains the pitfall trap and thus keeps its efficiency high. Using laboratory experiments, as well as finite-element analysis, we tested these hypotheses. We show, experimentally and numerically, that sand that accumulates at the centre of the pit will be removed continuously by sand-throwing, this maintenance is leading to slope condition close to an unstable state. This keeps the slope angle steep and the efficiency of the trap constant. Furthermore, the resulting sandslides can relocate the trapped prey towards the centre of the pit. This study adds further insights from specific mechanical properties of a granular medium into the behavioural context of hunting antlion larvae.
沙坑陷阱是一种精巧的结构，用于捕捉猎物。蚁狮利用其栖息地中颗粒之间的相互作用来建造一个稳定的陷阱。这个陷阱接近不稳定状态；当猎物进入陷阱时，它们会滑向蚁狮埋伏的中心。这种方式非常有效，但需要持续的维护。根据目前的知识，蚁狮主要通过投掷沙子来引起沙流向坑的中心流动。我们假设：(i) 投掷沙子会导致沙流向坑的中心流动，(ii) 投掷沙子会不断维护陷阱，从而保持其高效性。我们使用实验室实验和有限元分析来测试这些假设。我们通过实验和数值模拟表明，积聚在坑中心的沙子会被沙子的投掷不断地清除，这种维护会导致接近不稳定状态的边坡条件。这使得边坡角度陡峭，陷阱的效率保持不变。此外，由此产生的沙流可以将被困的猎物重新定位到坑的中心。这项研究从颗粒介质的特定力学性质角度进一步深入了解了捕猎蚁狮幼虫的行为背景。
