Zalophus hindflipper turning metrics and angle of attack

California sea lions (Zalophus californianus) are a highly maneuverable species of marine mammal. During uninterrupted, rectilinear swimming, sea lions oscillate their foreflippers to propel themselves forward without aid from the collapsed hindflippers, which are passively trailed. During maneuvers such as turning and leaping (porpoising), the hindflippers are spread into a delta-wing configuration. There is little information defining the role of otarrid hindflippers as aquatic control surfaces. To examine Z. californianus hindflippers during maneuvering, trained sea lions were video recorded underwater through viewing windows performing porpoising behaviors and banking turns. Porpoising by a trained sea lion was compared with sea lions executing the maneuver in the wild. Anatomical points of reference (ankle and hindflipper tip) were digitized from videos to analyze various performance metrics and define the use of the hindflippers. During a porpoising bout, the hindflippers were con...加州海狮（Zalophus californianus）是一种机动性极强的海洋哺乳动物。在不间断的直线游泳过程中，海狮通过摆动前鳍肢向前推进，此时收起的后鳍肢处于被动拖曳状态，不提供任何推进助力。在转向、豚泳（porpoising）等机动动作中，后鳍肢会展开为三角翼构型。目前尚无充分资料明确海狮科（otarrid）后鳍肢作为水下操控面的具体作用。为探究加州海狮在机动过程中后鳍肢的使用模式，研究人员通过观察窗对受训海狮的水下行为进行录像，记录其豚泳与倾斜转弯动作，并将受训海狮的豚泳行为与野生海狮的同类动作进行对比。研究人员从录像中对解剖学参考点（踝关节与后鳍肢尖端）进行数字化追踪，以分析多项性能指标并明确后鳍肢的使用方式。在一次豚泳过程中，后鳍肢……