Wisniewska Danuta M, Ratcliffe John M, Beedholm Kristian, Christensen Christian B, Johnson Mark, Koblitz Jens C, Wahlberg Magnus, Madsen Peter T
Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark.
Sound and Behaviour Group, Institute of Biology, University of Southern Denmark, Odense, Denmark.
Elife. 2015 Mar 20;4:e05651. doi: 10.7554/eLife.05651.
Toothed whales use sonar to detect, locate, and track prey. They adjust emitted sound intensity, auditory sensitivity and click rate to target range, and terminate prey pursuits with high-repetition-rate, low-intensity buzzes. However, their narrow acoustic field of view (FOV) is considered stable throughout target approach, which could facilitate prey escape at close-range. Here, we show that, like some bats, harbour porpoises can broaden their biosonar beam during the terminal phase of attack but, unlike bats, maintain the ability to change beamwidth within this phase. Based on video, MRI, and acoustic-tag recordings, we propose this flexibility is modulated by the melon and implemented to accommodate dynamic spatial relationships with prey and acoustic complexity of surroundings. Despite independent evolution and different means of sound generation and transmission, whales and bats adaptively change their FOV, suggesting that beamwidth flexibility has been an important driver in the evolution of echolocation for prey tracking.
齿鲸利用声纳来探测、定位和追踪猎物。它们会根据目标距离调整发出的声音强度、听觉灵敏度和点击频率，并以高重复率、低强度的嗡嗡声终止对猎物的追捕。然而，它们狭窄的声视野（FOV）在整个接近目标的过程中被认为是稳定的，这可能会便于猎物在近距离逃脱。在这里，我们表明，与一些蝙蝠一样，港湾鼠海豚在攻击的最后阶段可以拓宽它们的生物声纳波束，但与蝙蝠不同的是，它们在这个阶段仍保持改变波束宽度的能力。基于视频、磁共振成像（MRI）和声标签记录，我们提出这种灵活性是由鲸蜡器调节的，并用于适应与猎物的动态空间关系以及周围环境的声学复杂性。尽管鲸和蝙蝠独立进化，且声音产生和传播的方式不同，但它们都能适应性地改变它们的声视野，这表明波束宽度的灵活性一直是回声定位用于猎物追踪进化过程中的一个重要驱动因素。
