Department of Biological Sciences, Clemson University, Clemson, SC 29634, United States of America. Author to whom any correspondence should be addressed.
Bioinspir Biomim. 2018 Nov 7;14(1):016002. doi: 10.1088/1748-3190/aae906.
Stability and turning performance are two key metrics of locomotor performance in animals, and performance in both of these metrics can be improved through a variety of morphological structures. Aquatic vehicles are often designed with keels and rudders to improve their stability and turning performance, but how keels and rudders function in rigid-bodied animals is less understood. Aquatic turtles are a lineage of rigid-bodied animals that have the potential to function similarly to engineered vehicles, and also might make use of keels and rudders to improve their stability and turning performance. To test these possibilities, we trained turtles to follow a mechanically controlled prey stimulus under three sets of conditions: with no structural modifications, with different sized and shaped keels, and with restricted tail use. We predicted that keels in turtles would function similarly to those in aquatic vehicles to reduce oscillations, and that turtles would use the tail like a rudder to reduce oscillations and improve turning performance. We found that the keel designs we tested did not reduce oscillations in turtles, but that the tail was used similarly to a rudder, with benefits to both the magnitude of oscillations they experienced and turning performance. These data show how variation in the accessory structures of rigid-bodied animals can impact swimming performance, and suggest that such variation among turtles could serve as a biomimetic model in designing aquatic vehicles that are stable as well as maneuverable and agile.
稳定性和转向性能是动物运动性能的两个关键指标，这两个指标的性能都可以通过各种形态结构来提高。水上交通工具通常设计有龙骨和舵来提高其稳定性和转向性能，但龙骨和舵在刚性身体动物中的作用却知之甚少。水龟是一种具有刚性身体的动物谱系，它们有可能具有类似工程车辆的功能，并且可能利用龙骨和舵来提高其稳定性和转向性能。为了验证这些可能性，我们对海龟进行了训练，使其在三种条件下跟随机械控制的猎物刺激：无结构修改、不同大小和形状的龙骨以及限制使用尾巴。我们预测，海龟的龙骨将类似于水上交通工具中的龙骨，以减少振荡，并且海龟将像舵一样使用尾巴来减少振荡并提高转向性能。我们发现，我们测试的龙骨设计并没有减少海龟的振荡，但尾巴的作用类似于舵，对它们经历的振荡幅度和转向性能都有好处。这些数据表明，刚性身体动物的辅助结构的变化如何影响游泳性能，并表明海龟之间的这种变化可以作为设计稳定、可操纵和灵活的水上交通工具的仿生模型。
