Department of Biology, West Chester University, West Chester, PA 19383, USA.
Department of Physics and Engineering, West Chester University, West Chester, PA 19383, USA.
J Exp Biol. 2024 Jan 15;227(2). doi: 10.1242/jeb.246433. Epub 2024 Jan 30.
Cetaceans are capable of extraordinary locomotor behaviors in both water and air. Whales and dolphins can execute aerial leaps by swimming rapidly to the water surface to achieve an escape velocity. Previous research on spinner dolphins demonstrated the capability of leaping and completing multiple spins around their longitudinal axis with high angular velocities. This prior research suggested the slender body morphology of spinner dolphins together with the shapes and positions of their appendages allowed for rapid spins in the air. To test whether greater moments of inertia reduced spinning performance, videos and biologging data of cetaceans above and below the water surface were obtained. The principal factors affecting the number of aerial spins a cetacean can execute were moment of inertia and use of control surfaces for subsurface corkscrewing. For spinner dolphin, Pacific striped dolphin, bottlenose dolphin, minke whale and humpback whale, each with swim speeds of 6-7 m s-1, our model predicted that the number of aerial spins executable was 7, 2, 2, 0.76 and 1, respectively, which was consistent with observations. These data implied that the rate of subsurface corkscrewing was limited to 14.0, 6.8, 6.2, 2.2 and 0.75 rad s-1 for spinner dolphins, striped dolphins, bottlenose dolphins, minke whales and humpback whales, respectively. In our study, the moment of inertia of the cetaceans spanned a 21,000-fold range. The greater moments of inertia for the last four species produced large torques on control surfaces that limited subsurface corkscrewing motion and aerial maneuvers compared with spinner dolphins.
鲸目动物在水中和空气中都能进行非凡的运动行为。鲸鱼和海豚可以通过快速游向水面来达到逃逸速度，从而进行空中跳跃。以前对飞旋海豚的研究表明，它们有跳跃能力，并能以高速围绕其纵轴完成多次旋转。之前的研究表明，飞旋海豚的细长体型以及它们的附肢的形状和位置，使它们能够在空中快速旋转。为了测试较大的转动惯量是否会降低旋转性能，我们获取了水面上和水面下的鲸目动物的视频和生物标志数据。影响鲸目动物在空中执行旋转次数的主要因素是转动惯量和控制表面在水下螺旋运动中的使用。对于飞旋海豚、太平洋斑纹海豚、宽吻海豚、小须鲸和座头鲸，它们的游泳速度分别为 6-7 m s-1，我们的模型预测，它们在空中可执行的旋转次数分别为 7、2、2、0.76 和 1，这与观察结果一致。这些数据表明，水下螺旋运动的速度限制为飞旋海豚、斑纹海豚、宽吻海豚、小须鲸和座头鲸分别为 14.0、6.8、6.2、2.2 和 0.75 rad s-1。在我们的研究中，鲸目动物的转动惯量跨度为 21,000 倍。后四种物种的转动惯量较大，这导致控制表面上的转矩较大，限制了水下螺旋运动和空中机动，与飞旋海豚相比，这使得它们的水下螺旋运动和空中机动受到限制。
