Department of Biological Sciences, Clemson University, 132 Long Hall, Clemson, SC 29634, USA.
J Exp Biol. 2011 Apr 1;214(Pt 7):1153-62. doi: 10.1242/jeb.046045.
Hydrodynamic stability is the ability to resist recoil motions of the body produced by destabilizing forces. Previous studies have suggested that recoil motions can decrease locomotor performance, efficiency and sensory perception and that swimming animals might utilize kinematic strategies or possess morphological adaptations that reduce recoil motions and produce more stable trajectories. We used high-speed video to assess hydrodynamic stability during rectilinear swimming in the freshwater painted turtle (Chrysemys picta). Parameters of vertical stability (heave and pitch) were non-cyclic and variable, whereas measures of lateral stability (sideslip and yaw) showed repeatable cyclic patterns. In addition, because freshwater and marine turtles use different swimming styles, we tested the effects of propulsive mode on hydrodynamic stability during rectilinear swimming, by comparing our data from painted turtles with previously collected data from two species of marine turtle (Caretta caretta and Chelonia mydas). Painted turtles had higher levels of stability than both species of marine turtle for six of the eight parameters tested, highlighting potential disadvantages associated with 'aquatic flight'. Finally, available data on hydrodynamic stability of other rigid-bodied vertebrates indicate that turtles are less stable than boxfish and pufferfish.
水动力稳定性是指抵抗由失稳力产生的身体反冲运动的能力。先前的研究表明，反冲运动会降低运动性能、效率和感官感知，而游泳动物可能会利用运动学策略或具有形态适应能力来减少反冲运动并产生更稳定的轨迹。我们使用高速视频评估了淡水彩龟（Chrysemys picta）直线游泳时的水动力稳定性。垂直稳定性（升沉和俯仰）参数是非周期性和可变的，而侧向稳定性（侧滑和偏航）的测量值则表现出可重复的周期性模式。此外，由于淡水龟和海龟使用不同的游泳方式，我们通过比较彩龟的直线游泳数据与之前从两种海龟（Caretta caretta 和 Chelonia mydas）收集的数据，测试了推进模式对水动力稳定性的影响。在测试的八个参数中，有六个参数显示，彩龟比两种海龟的稳定性都高，这突出了与“水生飞行”相关的潜在劣势。最后，其他刚体脊椎动物水动力稳定性的可用数据表明，海龟的稳定性不如箱鲀和河豚。
