Murakami Hisashi, Tomaru Takenori, Gunji Yukio-Pegio
Department of Information Systems Creation, Kanagawa University, Yokohama, Kanagawa, Japan.
Department of Computer Science and Engineering, Toyohashi University of Technology, Toyohashi, Aichi, Japan.
R Soc Open Sci. 2017 Sep 20;4(9):170954. doi: 10.1098/rsos.170954. eCollection 2017 Sep.
Foraging fiddler crabs form a strict spatial relationship between their current positions and burrows, allowing them to run directly back to their burrows when startled even without visual contacts. Path integration (PI), the underlying mechanism, is a universal navigation strategy through which animals continuously integrate directions and distances of their movements. However, we report that fiddler crabs also use visual orientation during homing runs using burrow entrances as cues, with the prioritised mechanism (i.e. PI or visual) determined by the distance (which has a threshold value) between the goal, indicated by PI, and the visual cue. When we imposed homing errors using fake entrances (visual cue) and masking their true burrows (goal of PI), we found that frightened fiddler crabs initially ran towards the true burrow following PI, then altered their behaviour depending on the distance between the fake entrance and masked true burrow: if the distance was large, they kept running until they reached the true burrow, ignoring the visual cue; however, if the distance was small, they altered the homing path and ran until they reached the fake entrance. This suggests that PI and visual mechanism in fiddler crabs are mutually mediated to achieve their homing behaviour.
觅食的招潮蟹在其当前位置与洞穴之间形成了一种严格的空间关系，这使得它们即使在没有视觉接触的情况下受到惊吓时也能直接跑回自己的洞穴。作为其潜在机制的路径积分（PI）是一种通用的导航策略，动物通过这种策略不断整合其运动的方向和距离。然而，我们报告称，招潮蟹在归巢奔跑过程中也会利用洞穴入口作为线索进行视觉定向，优先机制（即PI或视觉）由PI指示的目标与视觉线索之间的距离（有一个阈值）决定。当我们使用假入口（视觉线索）制造归巢误差并掩盖它们真正的洞穴（PI的目标）时，我们发现受到惊吓的招潮蟹最初会按照PI朝着真正的洞穴奔跑，然后根据假入口与被掩盖的真正洞穴之间的距离改变它们的行为：如果距离很大，它们会一直跑到真正的洞穴，忽略视觉线索；然而，如果距离很小，它们会改变归巢路径并一直跑到假入口。这表明招潮蟹的PI和视觉机制相互调节以实现其归巢行为。
