School of Biological Sciences, University of Auckland, Auckland, New Zealand.
J Exp Biol. 2010 Nov 15;213(Pt 22):3819-31. doi: 10.1242/jeb.040741.
Blind Mexican cave fish (Astyanax fasciatus) sense the presence of nearby objects by sensing changes in the water flow around their body. The information available to the fish using this hydrodynamic imaging ability depends on the properties of the flow field it generates while gliding and how this flow field is altered by the presence of objects. Here, we used particle image velocimetry to measure the flow fields around gliding blind cave fish as they moved through open water and when heading towards a wall. These measurements, combined with computational fluid dynamics models, were used to estimate the stimulus to the lateral line system of the fish. Our results showed that there was a high-pressure region around the nose of the fish, low-pressure regions corresponding to accelerated flow around the widest part of the body and a thick laminar boundary layer down the body. When approaching a wall head-on, the changes in the stimulus to the lateral line were confined to approximately the first 20% of the body. Assuming that the fish are sensitive to a certain relative change in lateral line stimuli, it was found that swimming at higher Reynolds numbers slightly decreased the distance at which the fish could detect a wall when approaching head-on, which is the opposite to what has previously been expected. However, when the effects of environmental noise are considered, swimming at higher speed may improve the signal to noise ratio of the stimulus to the lateral line.
盲眼墨西哥洞穴鱼（Astyanax fasciatus）通过感知身体周围水流的变化来感知附近物体的存在。鱼类利用这种水动力成像能力获得的信息取决于其在滑行时产生的流场特性，以及物体存在时流场如何发生变化。在这里，我们使用粒子图像测速法来测量滑行中的盲眼洞穴鱼在穿过开阔水域和朝向墙壁时周围的流场。这些测量结果与计算流体动力学模型相结合，用于估计鱼类侧线系统的刺激。我们的研究结果表明，鱼的鼻子周围有一个高压区域，身体最宽处周围有低压区域，对应于加速的流动，身体下方有一层厚的层流边界层。当鱼正面接近墙壁时，侧线刺激的变化仅限于身体的前 20%左右。假设鱼类对侧线刺激的某些相对变化敏感，那么发现以较高的雷诺数游泳时，鱼在正面接近时能够探测到墙壁的距离略有缩短，这与之前的预期相反。然而，当考虑环境噪声的影响时，高速游泳可能会提高侧线刺激的信噪比。
