Department of Zoology, Research and Administration Building, 11a Mansfield Road, Oxford, OX1 3SZ, UK.
Commun Biol. 2022 Oct 1;5(1):1045. doi: 10.1038/s42003-022-03925-5.
Distance travelled is a crucial metric that underpins an animal's ability to navigate in the short-range. While there is extensive research on how terrestrial animals measure travel distance, it is unknown how animals navigating in aquatic environments estimate this metric. A common method used by land animals is to measure optic flow, where the speed of self-induced visual motion is integrated over the course of a journey. Whether freely-swimming aquatic animals also measure distance relative to a visual frame of reference is unclear. Using the marine fish Rhinecanthus aculeatus, we show that teleost fish can use visual motion information to estimate distance travelled. However, the underlying mechanism differs fundamentally from previously studied terrestrial animals. Humans and terrestrial invertebrates measure the total angular motion of visual features for odometry, a mechanism which does not vary with visual density. In contrast, the visual odometer used by Rhinecanthus acuelatus is strongly dependent on the visual density of the environment. Odometry in fish may therefore be mediated by a movement detection mechanism akin to the system underlying the optomotor response, a separate motion-detection mechanism used by both vertebrates and invertebrates for course and gaze stabilisation.
行进距离是动物在短距离内导航能力的关键指标。虽然已经有大量关于陆地动物如何测量行进距离的研究，但对于在水生环境中导航的动物如何估计这一指标，目前还不得而知。陆地动物常用的一种方法是测量光流，即对行进过程中的自身视觉运动速度进行积分。在水生环境中自由游动的动物是否也相对于视觉参照系来测量距离还不清楚。本研究以海水鱼波纹唇鱼为模型，展示了硬骨鱼类可以利用视觉运动信息来估计行进距离。然而，其潜在的机制与先前研究的陆地动物有根本的不同。人类和陆地无脊椎动物通过计程法来测量视觉特征的总角运动，这一机制与视觉密度无关。相比之下，波纹唇鱼所使用的视觉里程计强烈依赖于环境的视觉密度。因此，鱼类的计程可能是由类似于光顺应反应的运动检测机制介导的，光顺应反应是一种独立的运动检测机制，被脊椎动物和无脊椎动物用于稳定航向和凝视。
