Zoophysiology, Department of Biological Sciences, Aarhus University, 8000 Aarhus, Denmark.
Proc Biol Sci. 2011 Oct 22;278(1721):3017-25. doi: 10.1098/rspb.2010.2604. Epub 2011 Feb 23.
Toothed whales rely on sound to echolocate prey and communicate with conspecifics, but little is known about how extreme pressure affects pneumatic sound production in deep-diving species with a limited air supply. The short-finned pilot whale (Globicephala macrorhynchus) is a highly social species among the deep-diving toothed whales, in which individuals socialize at the surface but leave their social group in pursuit of prey at depths of up to 1000 m. To investigate if these animals communicate acoustically at depth and test whether hydrostatic pressure affects communication signals, acoustic DTAGs logging sound, depth and orientation were attached to 12 pilot whales. Tagged whales produced tonal calls during deep foraging dives at depths of up to 800 m. Mean call output and duration decreased with depth despite the increased distance to conspecifics at the surface. This shows that the energy content of calls is lower at depths where lungs are collapsed and where the air volume available for sound generation is limited by ambient pressure. Frequency content was unaffected, providing a possible cue for group or species identification of diving whales. Social calls may be important to maintain social ties for foraging animals, but may be impacted adversely by vessel noise.
齿鲸依靠声音回声定位猎物并与同类交流，但对于在空气供应有限的深海潜水物种中，极端压力如何影响气动声音产生，人们知之甚少。短鳍领航鲸（Globicephala macrorhynchus）是深海齿鲸中高度社会化的物种，其个体在水面上进行社交，但为了追逐猎物，它们会潜到深达 1000 米的地方。为了研究这些动物是否在深海中进行声学交流，并测试静压是否会影响通讯信号，研究人员将声学 DTAG（数据标签）附在 12 只领航鲸身上，该 DTAG 可以记录声音、深度和方向。标记的鲸鱼在深潜觅食潜水时会发出音调叫声，最深可达 800 米。尽管与水面上的同类的距离增加了，但平均叫声输出和持续时间随深度的增加而减少。这表明，在肺部塌陷且空气体积受环境压力限制而无法产生声音的深度，叫声的能量含量较低。频率内容不受影响，为潜水鲸鱼的群体或物种识别提供了一个可能的线索。社会叫声可能对觅食动物维持社交联系很重要，但可能会受到船只噪音的不利影响。
