title: Range-dependent flexibility in the acoustic field of view of echolocating porpoises (Phocoena phocoena).
abstract: 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.
authors: Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark.
authors: Danuta M
authors: http://orcid.org/0000-0002-3599-7440
authors: DM
authors: Wisniewska
authors: Sound and Behaviour Group, Institute of Biology, University of Southern Denmark, Odense, Denmark.
authors: John M
authors: JM
authors: Ratcliffe
authors: Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark.
authors: Kristian
authors: K
authors: Beedholm
authors: Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark.
authors: Christian B
authors: CB
authors: Christensen
authors: Scottish Oceans Institute, University of St Andrews, St Andrews, Scotland.
authors: Mark
authors: M
authors: Johnson
authors: Animal Physiology, Institute for Neurobiology, University of Tübingen, Tübingen, Germany.
authors: Jens C
authors: JC
authors: Koblitz
authors: Sound and Behaviour Group, Institute of Biology, University of Southern Denmark, Odense, Denmark.
authors: Magnus
authors: M
authors: Wahlberg
authors: Zoophysiology, Department of Bioscience, Aarhus University, Aarhus, Denmark.
authors: Peter T
authors: PT
authors: Madsen
mesh_terms: D000222:Adaptation, Physiological; D000825:Animal Structures / Q000033:anatomy & histology / Q000502:physiology*; D000818:Animals; D005075:Biological Evolution; D002685:Chiroptera / Q000033:anatomy & histology / Q000502:physiology*; D004455:Echolocation / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D008279:Magnetic Resonance Imaging; D008297:Male; D050741:Phocoena / Q000033:anatomy & histology / Q000502:physiology*; D011235:Predatory Behavior / Q000502:physiology; D013016:Sound; D014741:Video Recording; D014828:Vocalization, Animal / Q000502:physiology*
keywords: beam directionality; biosonar; buzz; convergent evolution; ecology; neuroscience; phocoena phocoena; prey capture