Nieder Carolin, Gibbs Brendan J, Rapson Jimmy, McLay Jessica, Montgomery John C, Radford Craig A
Institute of Marine Science, University of Auckland, Leigh Marine Research Laboratory, 160 Goat Island Road, Leigh, Auckland 0985, New Zealand.
The University of Florida, Whitney Laboratory for Marine Bioscience, 9505 N Ocean Shore Blvd, St. Augustine, FL 32080, USA.
J Exp Biol. 2023 Sep 15;226(18). doi: 10.1242/jeb.245995. Epub 2023 Sep 25.
Behavioural studies have shown that sharks are capable of directional orientation to sound. However, only one previous experiment addresses the physiological mechanisms of directional hearing in sharks. Here, we used a directional shaker table in combination with the auditory evoked potential (AEP) technique to understand the broadscale directional hearing capabilities in the New Zealand carpet shark (Cephaloscyllium isabellum), rig shark (Mustelus lenticulatus) and school shark (Galeorhinus galeus). The aim of this experiment was to test if sharks are more sensitive to vertical (z-axis) or head-to-tail (x-axis) accelerations, and whether there are any differences between species. Our results support previous findings, suggesting that shark ears can receive sounds from all directions. Acceleration detection bandwidth was narrowest for the carpet shark (40-200 Hz), and broader for rig and school sharks (40-800 Hz). Greatest sensitivity bands were 40-80 Hz for the carpet shark, 100-200 Hz for the rig and 80-100 Hz for the school shark. Our results indicate that there may be differences in directional hearing abilities among sharks. The bottom-dwelling carpet shark was equally sensitive to vertical and head-to-tail particle accelerations. In contrast, both benthopelagic rig and school sharks appeared to be more sensitive to vertical accelerations at frequencies up to 200 Hz. This is the first study to provide physiological evidence that sharks may differ in their directional hearing and sound localisation abilities. Further comparative physiological and behavioural studies in more species with different lifestyles, habitats and feeding strategies are needed to further explore the drivers for increased sensitivity to vertical accelerations among elasmobranchs.
行为学研究表明，鲨鱼能够对声音进行定向定位。然而，此前仅有一项实验研究了鲨鱼定向听觉的生理机制。在此，我们使用了一个定向振动台，并结合听觉诱发电位（AEP）技术，来了解新西兰毯鲨（Cephaloscyllium isabellum）、糙齿鲨（Mustelus lenticulatus）和狭纹虎鲨（Galeorhinus galeus）的广泛定向听觉能力。本实验的目的是测试鲨鱼对垂直（z轴）加速度还是头至尾（x轴）加速度更敏感，以及不同物种之间是否存在差异。我们的结果支持了先前的研究发现，表明鲨鱼的耳朵能够接收来自各个方向的声音。毯鲨的加速度检测带宽最窄（40 - 200Hz），糙齿鲨和狭纹虎鲨的带宽更宽（40 - 800Hz）。毯鲨的最大敏感频段为40 - 80Hz，糙齿鲨为100 - 200Hz，狭纹虎鲨为80 - 100Hz。我们的结果表明，鲨鱼之间的定向听觉能力可能存在差异。底栖的毯鲨对垂直和头至尾的粒子加速度同样敏感。相比之下，底栖性的糙齿鲨和狭纹虎鲨在高达200Hz的频率下似乎对垂直加速度更敏感。这是第一项提供生理证据表明鲨鱼在定向听觉和声音定位能力上可能存在差异的研究。需要在更多具有不同生活方式、栖息地和摄食策略的物种中进行进一步的比较生理学和行为学研究，以进一步探索软骨鱼类对垂直加速度敏感性增加的驱动因素。
