Fish F E
Department of Biology, West Chester University, PA 19383, USA.
J Exp Biol. 1998 Oct;201(Pt 20):2867-77.
Propulsive morphology and swimming performance were compared for the odontocete cetaceans Delphinapterus leucas, Orcinus orca, Pseudorca crassidens and Tursiops truncatus. Morphological differences were apparent among the whales. The general body contour and low-aspect-ratio caudal flukes of D. leucas indicated that this species was a low-performance swimmer compared with the other species. Propulsive motions were video-taped as animals swam steadily in large pools. Video tapes were analyzed digitally using a computerized motion-analysis system. Animals swam at relative velocities ranging from 0.4 to 2.4 body lengths s-1. The stroke amplitude of the flukes decreased linearly with velocity for D. leucas, but amplitude remained constant for the other species. Tail-beat frequencies were directly related to relative swimming velocity, whereas the pitch angle of the flukes was inversely related to relative swimming velocity. Unsteady lifting-wing theory was used with regression equations based on kinematics to calculate thrust power output, drag coefficients and propulsive efficiency. Compared with other species, O. orca generated the largest thrust power (36.3 kW) and had the lowest drag coefficient (0.0026), whereas T. truncatus displayed the largest mass-specific thrust power (23.7 W kg-1) and P. crassidens had the highest efficiency (0.9). D. leucas did not swim as rapidly as the other species and had a comparatively higher minimum drag coefficient (0.01), lower mass-specific thrust power (5.2 W kg-1) and lower maximum efficiency (0.84). Minimum drag coefficients were associated with high swimming speeds, and maximum efficiencies corresponded with velocities in the range of typical cruising speeds. The results indicate that the kinematics of the propulsive flukes and hydrodynamics are associated with the swimming behaviors and morphological designs exhibited by the whales in this study, although additional factors will influence morphology.
对齿鲸类的白鲸、虎鲸、伪虎鲸和宽吻海豚的推进形态和游泳性能进行了比较。这些鲸鱼之间存在明显的形态差异。白鲸的总体身体轮廓和低展弦比的尾鳍表明，与其他物种相比，该物种是低性能游泳者。当动物在大水池中稳定游动时，对其推进运动进行录像。使用计算机化运动分析系统对录像带进行数字分析。动物以0.4至2.4体长每秒的相对速度游动。白鲸尾鳍的冲程幅度随速度呈线性下降，但其他物种的幅度保持不变。尾拍频率与相对游泳速度直接相关，而尾鳍的俯仰角与相对游泳速度呈反比。基于运动学的回归方程结合非定常升力翼理论来计算推力功率输出、阻力系数和推进效率。与其他物种相比，虎鲸产生的推力功率最大（36.3千瓦），阻力系数最低（0.0026），而宽吻海豚表现出最大的质量比推力功率（23.7瓦/千克），伪虎鲸的效率最高（0.9）。白鲸游动速度不如其他物种快，具有相对较高的最小阻力系数（0.01）、较低的质量比推力功率（5.2瓦/千克）和较低的最大效率（0.84）。最小阻力系数与高游泳速度相关，最大效率与典型巡航速度范围内的速度相对应。结果表明，尽管还有其他因素会影响形态，但在本研究中，推进尾鳍的运动学和流体动力学与鲸鱼所表现出的游泳行为和形态设计相关。
