Tunas of the genusThunnusare a group of high-performance pelagic fishes with many locomotor traits that are convergently shared with other high-performance fish groups. Because of their swimming abilities, tunas continue to be an inspiration for both comparative biomechanics and the design of biomimetic autonomous underwater vehicles (AUVs). Despite the strong history of studies in tuna physiology and current interest in tuna biomechanics and bio-inspired design, we lack quantitative data on the function of many features of tunas. Here we present data on the morphology, behavior, and function of tunas, focusing especially on experimentally examining the function of tuna lateral keels, finlets, and pectoral fins by using simple physical models. We find that both triangular lateral keels and flexible finlets decrease power requirements during swimming, likely by reducing lateral forces and yaw torques (compared to models either without keels or with rectangular keels, and models with stiff finlets or strip fins of equal area, respectively). However, both triangular keels and flexible finlets generate less thrust than other models either without these features or with modified keels or finlets, leading to a tradeoff between power consumption and thrust. In addition, we use micro computed tomography (µCT) to show that the flexible lateral keels possess a lateral line canal, suggesting these keels have a sensory function. The curved and fully-attached base of tuna pectoral fins provides high lift-to-drag ratio at low angles of attack, and generates the highest torques across speeds and angles of attack. Therefore, curved, fully-attached pectoral fins grant both better gliding and maneuvering performance compared to flat or curved, partially-attached designs. We provide both three-dimensional models of tuna morphology derived from µCT scans and conclusions about the performance effects of tuna-like features as a resource for future biological and engineering work for next-generation tuna-inspired AUV designs.

中文翻译：

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Tunas是一个高性能的鱼类平台，可激发下一代自动水下航行器。

金枪鱼属的金枪鱼是一组具有许多运动性状的高性能远洋鱼类，与其他高性能鱼类群体共有。由于其游泳能力，金枪鱼继续成为比较生物力学和仿生自动水下航行器（AUV）设计的灵感。尽管金枪鱼生理学研究历史悠久，并且目前对金枪鱼生物力学和生物启发设计感兴趣，但我们缺乏有关金枪鱼许多功能的定量数据。在这里，我们介绍有关金枪鱼的形态，行为和功能的数据，尤其侧重于通过使用简单的物理模型通过实验检查金枪鱼侧向龙骨，鱼鳍和胸鳍的功能。我们发现，三角形的侧向龙骨和柔性翼片都可以降低游泳时的动力需求，这可能是通过减小侧向力和偏航扭矩来降低的（与没有龙骨或带有矩形龙骨的模型以及分别具有相等面积的刚性翼片或带状鳍片的模型相比） 。但是，三角龙骨和柔性翼片产生的推力都比不具有这些功能或具有改进的龙骨或翼片的其他型号要少，从而导致了功率消耗和推力之间的权衡。此外，我们使用微计算机断层扫描（µCT）来显示柔性侧向龙骨具有侧向线管，表明这些龙骨具有感觉功能。金枪鱼胸鳍的弯曲且完全连接的底部在低攻角下可提供较高的升阻比，并在各个速度和攻角上产生最高的扭矩。因此，与平坦或弯曲的部分连接设计相比，弯曲的完全连接的胸鳍可提供更好的滑行和操纵性能。我们提供了从µCT扫描得出的金枪鱼形态的三维模型，并提供了有关金枪鱼样特征的性能影响的结论，作为下一代金枪鱼启发式AUV设计的未来生物学和工程工作的资源。