Static visual predator recognition in jumping spiders

Visually detecting, recognizing, and responding appropriately to predators increases survival. Failure to detect a predator or long decision times carry high and potentially fatal costs. Consequently, many animals show general anti-predatory responses toward threatening stimuli, e.g., looming objects. However, in the context of lurking or stalking ambush predators, visual recognition is based on static visual cues, making this task computationally demanding. Jumping spiders (Salticidae) have superb vision and are excellent ambush predators but they can equally fall prey to other jumping spiders. In a hierarchical decision-making setup, we tested whether the common zebra jumping spider (<em>Salticus scenicus</em>) can visually recognize stationary predators. We measured the spiders’ behavioural responses towards predator (naturally co-occurring, non-co-occurring and artificial) and non-predator objects as well as towards objects with modified features. Our experiments show that salticids demonstrate a robust, fast, and repeatable “freeze and retreat” behaviour when presented with stationary predators, but not similarly sized non-predator objects. Anti-predator responses were triggered by co-occurring and non-co-occurring salticid predators, as well as by 3D-printed salticid models (based on micro-CT scans), suggesting a generalized predator detection/classification. Using modified 3D-printed models, we found evidence that eyes act as an important cue. However, eyes alone did not explain the responses, suggesting that underlying processes rely on multiple rather than single features. To address the role of learning and memory, we tested newly emerged spiderlings and found the same behavioural responses towards predator objects suggesting an innate response. The ability of jumping spiders to innately recognize a non-moving threat is surprising in terms of underlying cognitive processes and the evolution thereof. Escaping from a predator before an attack has been launched likely carries sufficient selective benefits. From a cognitive perspective, the overlap of static visual characteristics between salticid predators, prey, and conspecifics invites further questions considering the mechanisms of such nuanced visual discrimination and categorization in animals with complex vision but relatively small nervous systems.通过视觉检测、识别捕食者并做出恰当应对，可提升动物的生存概率。若未能检测到捕食者，或是决策耗时过长，则会招致高昂乃至致命的代价。因此，诸多动物会对具有威胁性的刺激（如逼近的物体）表现出一般性的反捕食行为。然而，针对潜伏或潜行的伏击型捕食者，视觉识别需依赖静态视觉线索，该任务的计算复杂度极高。跳蛛科（Salticidae）蜘蛛拥有卓越的视觉系统，同时也是出色的伏击型捕食者，但它们同样可能成为其他跳蛛的猎物。本研究通过层级决策实验范式，测试了常见斑马跳蛛（*Salticus scenicus*）能否通过视觉识别静止的捕食者。我们测定了跳蛛对三类捕食者（自然共存、非自然共存及人工构建的捕食者）、非捕食者物体，以及经过特征改造的物体的行为反应。实验结果显示，当面对静止捕食者时，跳蛛科蜘蛛会表现出稳定、快速且可重复的“僵住并后撤”行为，而面对尺寸相近的非捕食者物体时则无此类反应。自然共存与非自然共存的跳蛛捕食者，以及基于显微计算机断层扫描（micro-CT scans）制作的3D打印跳蛛模型，均可触发此类反捕食行为，这提示跳蛛具备通用的捕食者检测与分类机制。通过改造3D打印模型，我们发现眼部是重要的识别线索，但仅依靠眼部特征不足以解释全部行为反应，这说明其背后的认知过程依赖多特征整合而非单一特征。为探究学习与记忆在该过程中的作用，我们测试了刚孵化的幼蛛，发现其对捕食者物体同样表现出上述行为反应，提示该行为属于先天本能。跳蛛能够先天识别静止威胁这一能力，在潜在认知过程及其演化层面均令人意外。在攻击发起前便完成逃逸，显然具备足够的选择优势。从认知科学视角来看，跳蛛的捕食者、猎物以及同类的静态视觉特征存在重叠，这为进一步研究这类精细的视觉分辨与分类机制提供了新的研究方向——在拥有复杂视觉系统但神经系统相对微小的动物中，如何实现如此精准的视觉辨别与归类？