Holzman Roi, Perkol-Finkel Shimrit, Zilman Gregory
Department of Zoology, Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel The Inter-University Institute for Marine Sciences, POB 469, Eilat 88103, Israel
School of Mechanical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel.
J Exp Biol. 2014 Jun 1;217(Pt 11):1955-62. doi: 10.1242/jeb.098384. Epub 2014 Mar 27.
Fish commonly use their lateral line system to detect moving bodies such as prey and predators. A remarkable case is the Mexican blind cavefish Astyanax fasciatus, which evolved the ability to detect non-moving obstacles. The swimming body of A. fasciatus generates fluid disturbances, the alteration of which by an obstacle can be sensed by the fish's lateral line system. It is generally accepted that these alterations can provide information on the distance to the obstacle. We observed that A. fasciatus swimming in an unfamiliar environment open and close their mouths at high frequency (0.7-4.5 Hz) in order to generate suction flows. We hypothesized that repeated mouth suction generates a hydrodynamic velocity field, which is altered by an obstacle, inducing pressure gradients in the neuromasts of the lateral line and corresponding strong lateral line stimuli. We observed that the frequency and rate of mouth-opening events varied with the fish's distance to obstacles, a hallmark of pulse-based navigation mechanisms such as echolocation. We formulated a mathematical model of this hitherto unrecognized mechanism of obstacle detection and parameterized it experimentally. This model suggests that suction flows induce lateral line stimuli that are weakly dependent on the fish's speed, and may be an order of magnitude stronger than the correspondent stimuli induced by the fish's gliding body. We illustrate that A. fasciatus can navigate non-visually using a combination of two deeply ancestral and highly conserved mechanisms of ray-finned fishes: the mechanism of sensing water motion by the lateral line system and the mechanism of generating water motion by mouth suction.
鱼类通常利用它们的侧线系统来探测移动的物体，如猎物和捕食者。一个显著的例子是墨西哥盲穴鱼（Astyanax fasciatus），它进化出了探测静止障碍物的能力。墨西哥盲穴鱼的游动身体会产生流体扰动，障碍物对这种扰动的改变能够被鱼的侧线系统感知到。人们普遍认为，这些改变可以提供有关与障碍物距离的信息。我们观察到，墨西哥盲穴鱼在不熟悉的环境中游泳时会高频（0.7 - 4.5赫兹）地张开和闭合嘴巴，以便产生吸入流。我们推测，反复的嘴巴吸气会产生一个流体动力速度场，该速度场会被障碍物改变，从而在侧线的神经丘中诱导出压力梯度以及相应强烈的侧线刺激。我们观察到，张嘴事件的频率和速率会随着鱼与障碍物的距离而变化，这是基于脉冲的导航机制（如回声定位）的一个标志。我们构建了一个关于这种此前未被认识的障碍物探测机制的数学模型，并通过实验对其进行了参数化。该模型表明，吸入流诱导的侧线刺激对鱼的速度依赖性较弱，并且可能比鱼的滑行身体诱导的相应刺激强一个数量级。我们证明，墨西哥盲穴鱼可以通过结合硬骨鱼的两种深度祖传且高度保守的机制进行非视觉导航：通过侧线系统感知水运动的机制和通过嘴巴吸气产生水运动的机制。
