Piscitelli Marina A, McLellan William A, Rommel Sentiel A, Blum James E, Barco Susan G, Pabst D Ann
Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina 28403, USA.
J Morphol. 2010 Jun;271(6):654-73. doi: 10.1002/jmor.10823.
Shallow-diving, coastal bottlenose dolphins (Tursiops truncatus) and deep-diving, pelagic pygmy and dwarf sperm whales (Kogia breviceps and K. sima) will experience vastly different ambient pressures at depth, which will influence the volume of air within their lungs and potentially the degree of thoracic collapse they experience. This study tested the hypotheses that lung size will be reduced and/or thoracic mobility will be enhanced in deeper divers. Lung mass (T. truncatus, n = 106; kogiids, n = 18) and lung volume (T. truncatus, n = 5; kogiids, n = 4), relative to total body mass, were compared. One T. truncatus and one K. sima were cross-sectioned to calculate lung, thoracic vasculature, and other organ volumes. Excised thoraxes (T. truncatus, n = 3; kogiids, n = 4) were mechanically manipulated to compare changes in thoracic cavity shape and volume. Kogiid lungs were half the mass and one-fifth the volume of those of similarly sized T. truncatus. The lungs occupied only 15% of the total thoracic cavity volume in K. sima and 37% in T. truncatus. The kogiid and dolphin thoraxes underwent similar changes in shape and volume, although the width of the thoracic inlet was relatively constrained in kogiids. A broader phylogenetic comparison demonstrated that the ratio of lung mass to total body mass in kogiids, physeterids, and ziphiids was similar to that of terrestrial mammals, while delphinids and phocoenids possessed relatively large lungs. Thus, small lung size in deep-diving odontocetes may be a plesiomorphic character. The relatively large lung size of delphinids and phocoenids appears to be a derived condition that may permit the lung to function as a site of respiratory gas exchange throughout a dive in these rapid breathing, short-duration, shallow divers.
浅海潜水的沿海宽吻海豚（瓶鼻海豚）和深海潜水的远洋侏儒抹香鲸及小抹香鲸，在深度上会经历截然不同的环境压力，这会影响它们肺部内空气的体积，并可能影响它们所经历的胸廓塌陷程度。本研究检验了以下假设：在更深的潜水动物中，肺的大小会减小和/或胸廓的活动度会增强。比较了相对于总体重的肺质量（瓶鼻海豚，n = 106；小抹香鲸科，n = 18）和肺体积（瓶鼻海豚，n = 5；小抹香鲸科，n = 4）。对一头瓶鼻海豚和一头小抹香鲸进行了横断面解剖，以计算肺、胸廓血管系统和其他器官的体积。对切除的胸廓（瓶鼻海豚，n = 3；小抹香鲸科，n = 4）进行机械操作，以比较胸腔形状和体积的变化。小抹香鲸科的肺质量是同等大小瓶鼻海豚肺质量的一半，体积是其五分之一。在小抹香鲸中，肺仅占胸腔总体积的15%，而在瓶鼻海豚中占37%。小抹香鲸科和海豚的胸廓在形状和体积上经历了相似的变化，尽管小抹香鲸科胸廓入口的宽度相对受限。更广泛的系统发育比较表明，小抹香鲸科、抹香鲸科和喙鲸科的肺质量与总体重之比与陆生哺乳动物相似，而海豚科和鼠海豚科拥有相对较大的肺。因此，深海潜水齿鲸类动物较小的肺大小可能是一个原始特征。海豚科和鼠海豚科相对较大的肺大小似乎是一种衍生状态，这可能使肺在这些呼吸急促、潜水时间短、潜水浅的动物的整个潜水过程中作为呼吸气体交换的场所发挥作用。
