Can a spider web be too sticky? Tensile mechanics constrains the evolution of capture spiral stickiness in orb-weaving spiders
Can a spider web be too sticky? Tensile mechanics constrains the evolution of capture spiral stickiness in orb-weaving spiders
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DOI：
10.1111/j.1469-7998.2009.00558.x
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发表时间：
2009-06-01
影响因子：
2
通讯作者：
Blackledge, T. A.
中科院分区：
文献类型：
--
作者：
Agnarsson, I.;Blackledge, T. A.
织珠蜘蛛依靠粘性的捕捉线来保持猎物足够长的时间，以便定位和攻击。粘性丝的进化与蜘蛛类圆织蜘蛛的高度多样性有关，部分原因是它的生产成本比deinopoid圆织蜘蛛使用的原始干燥筛状纤维粘合剂更便宜。与筛状线不同，粘性胶对它所装饰的捕获螺旋的拉伸强度贡献很小。然而，粘性丝利用独特的吊桥机制，在cribellate丝中不存在，其通过招募多个胶滴的粘附来增加总粘性。在这里，我们分析粘性的丝和各种生物力学和建筑特征的网络，可能会影响其演变之间的关系，在17 ecribellate orb-weaving物种的样本。破坏捕获螺旋纤维所需的力是唯一最重要的因素，可以解释圆蛛粘性变化的90%。粘性随捕获螺旋强度线性增加，但具有显著的安全系数，因为粘性总是小于使丝断裂所需的力。因此，我们的研究结果表明，捕获螺旋的粘性的进化变化在很大程度上受到胶水放置在纤维上的强度的限制，而不是胶水本身的化学性质。这意味着当丝线能够反复分离并粘附在苦苦挣扎的猎物上时，圆网的功能达到最佳状态。
Orb-weaving spiders rely on sticky capture threads to retain prey long enough to be located and attacked. The evolution of viscid silk is associated with the high diversity of araneoid orb-weaving spiders, in part because it is cheaper to produce than the primitive dry cribellate fibrous adhesive used by deinopoid orb-weaving spiders. Unlike cribellate threads, viscid glue contributes little to the tensile strength of the capture spiral it decorates. However, viscid silk utilizes a unique suspension bridge mechanism, absent in cribellate silk, which increases total stickiness by recruiting the adhesion of multiple glue droplets. Here, we analyze the relationship between stickiness of viscid silk and various biomechanical and architectural features of webs that may influence its evolution, across a sample of 17 ecribellate orb-weaving species. The force required to break capture spiral fibers is the single most important factor explaining about 90% of the variation in stickiness among orb spiders. Stickiness increases linearly with capture spiral strength, but with a significant safety factor because stickiness is always less than the force required to break the silk. Our results thus indicate that evolutionary changes in the stickiness of the capture spiral are largely constrained by the strength of the fiber the glue is placed on rather than by the chemistry of the glue itself. This implies that orb webs function optimally when threads are able to detach and adhere repeatedly to struggling prey.