Cardiac morphology and mass have been associated with activity levels for bony fishes and elasmobranchs; however, there is little information on cardiac morphology of deep-sea sharks (living primarily below 200 m) and how that morphology compares to cardiac morphology of shallow coastal species. We examined relative heart mass and relative ventricle dry mass in 10 species of sharks from coastal to bathydemersal habitats (23–870 m) to test our hypothesis that relative heart mass decreases with depth. Relative heart mass and relative ventricle dry mass decreased with increasing depth of capture for sharks. The coastal, obligate ram ventilator Carcharhinus limbatus had the highest relative heart mass (1.17 g/kg) and relative ventricle dry mass (0.18 g/kg), whereas the deep-sea species Centrophorus uyato had the lowest (relative heart mass, 0.34 g/kg; relative ventricle dry mass, 0.057 g/kg). Our findings of decreasing relative heart and ventricle size with increasing depth support the visual interaction hypothesis as an explanation for reduced metabolic capacity in deep-sea sharks.

中文翻译：

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随着深度的增加，深海和沿海鲨鱼之间相对心脏质量的差异

心脏形态和质量与硬骨鱼和软骨鱼的活动水平有关；然而，关于深海鲨鱼（主要生活在 200 米以下）心脏形态以及该形态与浅海沿岸物种心脏形态相比的信息很少。我们检查了从沿海到深海栖息地（23-870 m）的 10 种鲨鱼的相对心脏质量和相对心室干质量，以检验我们的假设，即相对心脏质量随深度而减少。相对心脏质量和相对心室干质量随着鲨鱼捕获深度的增加而减少。沿海专性 ram 呼吸机 Carcharhinuslimbatus 的相对心脏质量 (1.17 g/kg) 和相对心室干质量 (0.18 g/kg) 最高，而深海物种 Centrophorus uyato 最低（相对心脏质量，0.34 g /公斤; 相对心室干质量，0.057 g/kg）。我们随着深度增加而减少相对心脏和心室大小的发现支持视觉交互假设，作为深海鲨鱼代谢能力降低的解释。