Hanson S E, Ray W J, Santhanakrishnan A, Patek S N
Department of Biology, Duke University, Durham, NC 27708, USA.
School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK 74078, USA.
Integr Org Biol. 2023 Jun 27;5(1):obad019. doi: 10.1093/iob/obad019. eCollection 2023.
Across countless marine invertebrates, coordination of closely spaced swimming appendages is key to producing diverse locomotory behaviors. Using a widespread mechanism termed hybrid metachronal propulsion, mantis shrimp swim by moving five paddle-like pleopods along their abdomen in a posterior to anterior sequence during the power stroke and a near-synchronous motion during the recovery stroke. Despite the ubiquity of this mechanism, it is not clear how hybrid metachronal swimmers coordinate and modify individual appendage movements to achieve a range of swimming capabilities. Using high-speed imaging, we measured pleopod kinematics of mantis shrimp (), while they performed two swimming behaviors: burst swimming and taking off from the substrate. By tracking each of the five pleopods, we tested how stroke kinematics vary across swimming speeds and the two swimming behaviors. We found that mantis shrimp achieve faster swimming speeds through a combination of higher beat frequencies, smaller stroke durations, and partially via larger stroke angles. The five pleopods exhibit non-uniform kinematics that contribute to the coordination and forward propulsion of the whole system. Micro-hook structures (retinacula) connect each of the five pleopod pairs and differ in their attachment across pleopods-possibly contributing to passive kinematic control. We compare our findings in to previous studies to identify commonalities across hybrid metachronal swimmers at high Reynolds numbers and centimeter scales. Through our large experimental dataset and by tracking each pleopod's movements, our study reveals key parameters by which mantis shrimp adjust and control their swimming, yielding diverse locomotor abilities.
在无数海洋无脊椎动物中，紧密排列的游泳附肢的协调是产生多样运动行为的关键。螳螂虾利用一种被称为混合交错推进的广泛机制游泳，在动力冲程期间，它们沿着腹部从后向前依次移动五个桨状的腹肢，在恢复冲程期间则进行近乎同步的运动。尽管这种机制很普遍，但尚不清楚混合交错游泳者如何协调和改变单个附肢的运动以实现一系列游泳能力。我们使用高速成像技术，测量了螳螂虾在进行两种游泳行为时的腹肢运动学，这两种行为分别是爆发式游泳和从基质上起飞。通过跟踪五个腹肢中的每一个，我们测试了冲程运动学如何随游泳速度和两种游泳行为而变化。我们发现，螳螂虾通过更高的拍频、更短的冲程持续时间以及部分通过更大的冲程角度的组合来实现更快的游泳速度。五个腹肢表现出不均匀的运动学，这有助于整个系统的协调和向前推进。微钩结构（系韧带）连接五个腹肢对中的每一对，并且它们在不同腹肢上的附着方式不同——这可能有助于被动运动控制。我们将我们在[具体研究对象]中的发现与之前的研究进行比较，以确定在高雷诺数和厘米尺度下混合交错游泳者的共同特征。通过我们庞大的实验数据集以及跟踪每个腹肢的运动，我们的研究揭示了螳螂虾调整和控制其游泳的关键参数，从而产生多样的运动能力。
