Data from: Passively stuck: death does not affect gecko adhesion strength

Many geckos use adhesive toe pads on the bottom of their digits to attach to surfaces with remarkable strength. Although gecko adhesion has been studied for hundreds of years, gaps exist in our understanding at the whole-animal level. It remains unclear whether the strength and maintenance of adhesion are determined by the animal or are passively intrinsic to the system. Here we show, for the first time, that strong adhesion is produced passively at the whole-animal level. Experiments on both live and recently euthanized tokay geckos (Gekko gecko) revealed that death does not affect the dynamic adhesive force or motion of a gecko foot when pulled along a vertical surface. Using a novel device that applied repeatable and steady-increasing pulling forces to the foot in shear, we found that the adhesive force was similarly high and variable when the animal was alive (mean ± s.d. = 5.4 ± 1.7 N) and within 30 min after death (5.4 ± 2.1 N). However, kinematic analyses showed that live geckos are able to control the degree of toe pad engagement and can rapidly stop strong adhesion by hyperextending the toes. This study offers the first assessment of whole-animal adhesive force under extremely controlled conditions. Our findings reveal that dead geckos maintain the ability to adhere with the same force as living animals, disproving that strong adhesion requires active control.诸多壁虎均依靠其趾腹的粘附式趾垫，以优异的附着强度贴合于各类表面。尽管壁虎粘附机制的研究已有数百年历史，但学界对整体动物层面的粘附特性仍存在认知空白，目前尚不明确粘附强度与粘附维持能力究竟由动物主动调控，还是该系统本身固有的被动属性。本研究首次证实，壁虎的强粘附能力可在整体动物层面被动产生。本研究对活体及刚安乐死的大壁虎（Gekko gecko）开展实验，结果显示，当沿垂直表面牵拉壁虎足部时，死亡并不会改变其足部的动态粘附力与运动状态。通过一款可对足部施加可重复、平稳递增剪切拉力的新型实验装置，我们发现，活体壁虎与死后30分钟内的壁虎，其粘附力均处于较高水平且波动相近：活体组平均粘附力为5.4±1.7牛，死后组为5.4±2.1牛。但运动学分析显示，活体壁虎可主动调控趾垫的贴合程度，并通过过度伸展足部快速终止强粘附。本研究首次在严格可控的实验条件下对整体动物的粘附力进行了评估，研究结果表明，死亡壁虎仍可保持与活体壁虎同等的粘附能力，这一发现驳斥了“强粘附需要主动调控”的观点。