Hybrid Metachronal Rowing Augments Swimming Speed and Acceleration via Increased Stroke Amplitude
Hybrid Metachronal Rowing Augments Swimming Speed and Acceleration via Increased Stroke Amplitude
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DOI：
10.1093/icb/icab141
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发表时间：
2021-06-18
影响因子：
2.6
通讯作者：
Santhanakrishnan, Arvind
中科院分区：
文献类型：
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作者：
Ford, Mitchell P.;Ray, William J.;Santhanakrishnan, Arvind
许多水生无脊椎动物在游泳时使用基于拖曳的异时划桨，在这种划桨中，紧密排列的附肢从后方开始摆动，每个附肢相对于其相邻的附肢在时间上发生相移。持续游动的物种，如南极磷虾，通常使用由超时动力划水和超时恢复划水组成的“纯超时划桨”，而突发性游泳物种，如许多桡足类和螳螂，则通常使用“混合超时划桨”，即先超时动力划桨，然后是同步或接近同步的恢复划桨。突发性游泳生物需要快速加速才能捕获猎物和/或逃避捕食，目前尚不清楚与纯超三角划船相比，混合超三角划艇是否能提高加速度和游泳速度。对刚性划桨进行简谐运动的模拟结果表明，相邻划桨之间的碰撞限制了纯次划桨的最大划程幅度。与在螳螂(Neogonodactylus Bredini)中观察到的类似的杂交超时划桨允许在更大的划程幅度下振荡，同时避免这些碰撞。我们使用自行式机器人，对比研究了纯超三角赛艇策略和混合超三角赛艇策略的游泳速度、加速度和尾流结构。机器人的游泳速度和峰值加速度均随行程幅值的增大而增大。混合超时划艇允许在更大的划程幅度下操作，而不会与机器人上的相邻划桨碰撞，从而提高游泳速度和峰值加速度。混合超时划产生了分散的尾迹，不同于纯超时划产生的更窄、向下倾斜的喷流。我们的发现表明，附肢间距较小的突发性游泳动物，如桡足类和螳螂，可以使用混合亚时划桨通过增加划程幅度来产生较大的加速度，而无需考虑附肢碰撞。
Numerous aquatic invertebrates use drag-based metachronal rowing for swimming, in which closely spaced appendages are oscillated starting from the posterior, with each appendage phase-shifted in time relative to its neighbor. Continuously swimming species such as Antarctic krill generally use "pure metachronal rowing" consisting of a metachronal power stroke and a metachronal recovery stroke, while burst swimming species such as many copepods and mantis shrimp typically use "hybrid metachronal rowing" consisting of a metachronal power stroke followed by a synchronous or nearly synchronous recovery stroke. Burst swimming organisms need to rapidly accelerate in order to capture prey and/or escape predation, and it is unknown whether hybrid metachronal rowing can augment acceleration and swimming speed compared to pure metachronal rowing. Simulations of rigid paddles undergoing simple harmonic motion showed that collisions between adjacent paddles restrict the maximum stroke amplitude for pure metachronal rowing. Hybrid metachronal rowing similar to that observed in mantis shrimp (Neogonodactylus bredini) permits oscillation at larger stroke amplitude while avoiding these collisions. We comparatively examined swimming speed, acceleration, and wake structure of pure and hybrid metachronal rowing strategies by using a self-propelling robot. Both swimming speed and peak acceleration of the robot increased with increasing stroke amplitude. Hybrid metachronal rowing permitted operation at larger stroke amplitude without collision of adjacent paddles on the robot, augmenting swimming speed and peak acceleration. Hybrid metachronal rowing generated a dispersed wake unlike narrower, downward-angled jets generated by pure metachronal rowing. Our findings suggest that burst swimming animals with small appendage spacing, such as copepods and mantis shrimp, can use hybrid metachronal rowing to generate large accelerations via increasing stroke amplitude without concern of appendage collision.