Williams T M, Kooyman G L, Croll D A
Physiological Research Laboratory, Scripps Institution of Oceanography, La Jolla, CA 92037.
J Comp Physiol B. 1991;160(6):637-44. doi: 10.1007/BF00571261.
Respiratory, metabolic, and cardiovascular responses to swimming were examined in two species of pinniped, the harbor seal (Phoca vitulina) and the California sea lion (Zalophus californianus). 1. Harbor seals remained submerged for 82-92% of the time at swimming speeds below 1.2 m.s-1. At higher speeds, including simulated speeds above 1.4 m.s-1, the percentage of time spent submerged decreased, and was inversely related to body weight. In contrast, the percentage of time spent submerged did not change with speed for sea lions swimming from 0.5 m.s-1 to 4.0 m.s-1. 2. During swimming, harbor seals showed a distinct breathhold bradycardia and ventilatory tachycardia that were independent of swimming speed. Average heart rate was 137 beats.min-1 when swimming on the water surface and 50 beats.min-1 when submerged. A bimodal pattern of heart rate also occurred in sea lions, but was not as pronounced as in the seals. 3. The weighted average heart rate (WAHR), calculated from measured heart rate and the percentage time spent on the water surface or submerged, increased linearly with swimming speed for both species. The graded increase in heart rate with exercise load is similar to the response observed for terrestrial mammals. 4. The rate of oxygen consumption increased exponentially with swimming speed in both seals and sea lions. The minimum cost of transport calculated from these rates ranged from 2.3 to 3.6 J.m-1.kg-1, and was 2.5-4.0 times the level predicted for similarly-sized salmonids. Despite different modes of propulsion and physiological responses to swimming, these pinnipeds demonstrate similar transport costs.
研究了两种鳍足类动物，即港海豹（Phoca vitulina）和加利福尼亚海狮（Zalophus californianus）对游泳的呼吸、代谢和心血管反应。1. 在游泳速度低于1.2米/秒时，港海豹82%至92%的时间处于水下。在更高速度下，包括模拟速度超过1.4米/秒时，水下停留时间百分比下降，且与体重呈负相关。相比之下，海狮在0.5米/秒至4.0米/秒游泳时，水下停留时间百分比不随速度变化。2. 游泳过程中，港海豹表现出明显的屏气性心动过缓和通气性心动过速，且与游泳速度无关。在水面游泳时平均心率为137次/分钟，水下时为50次/分钟。海狮也出现了双峰心率模式，但不如海豹明显。3. 根据测量的心率和在水面或水下停留的时间百分比计算得出的加权平均心率（WAHR），在两种动物中均随游泳速度线性增加。心率随运动负荷的分级增加与陆地哺乳动物的反应相似。4. 海豹和海狮的氧气消耗率均随游泳速度呈指数增加。根据这些速率计算出的最低运输成本范围为2.3至3.6焦耳/米·千克，是同样大小鲑科鱼类预测水平的2.5至4.0倍。尽管推进方式和对游泳的生理反应不同，但这些鳍足类动物表现出相似的运输成本。
