[MARMAM] New publication: Narrow Acoustic Field of View Drives Frequency Scaling in Toothed Whale Biosonar

Frants Jensen frants.jensen at gmail.com
Sun Nov 18 09:56:04 PST 2018


On behalf of my co-authors, I am pleased to announce our new paper
investigating scaling of toothed whale biosonar to evaluate the
evolutionary drivers of aquatic biosonar operation:

Jensen F. H., Johnson M., Ladegaard M., Wisniewska D., Madsen P. T.: Narrow
acoustic field of view drives frequency scaling in toothed whale biosonar.
Current Biology (2018), https://doi.org/10.1016/j.cub.2018.10.037

*Abstract: *Toothed whales are apex predators varying in size from 40-kg
porpoises to 50-ton sperm whales that all forage by emitting high-amplitude
ultrasonic clicks and listening for weak returning echoes. The sensory
field of view of these echolocating animals depends on the characteristics
of the biosonar signals and the morphology of the sound generator, yet it
is poorly understood how these biophysical relationships have shaped the
evolution of biosonar parameters as toothed whales adapted to different
foraging niches. Here we test how biosonar output, frequency, and
directivity vary with body size to understand the co-evolution of biosonar
signals and sound-generating structures. We show that the radiated power
increases twice as steeply with body mass (P ∝ M1.47 ± 0.25) than expected
from typical scaling laws of call intensity, indicating an evolutionary
hyperallometric investment into sound production structures that may be
driven by a strong selective pressure for long-range biosonar. We find that
biosonar frequency scales inversely with body size (F ∝ M−0.19 ± 0.03),
resulting in remarkably stable biosonar beamwidth that is independent of
body size. We discuss why the three main hypotheses for inverse frequency
scaling in animal communication signals do not explain frequency scaling in
toothed whale biosonar. We instead propose that a narrow acoustic field of
view, analogous to the fovea of many visual predators, is the primary
evolutionary driver of biosonar frequency in toothed whales, serving as a
spatial filter to reduce clutter levels and facilitate long-range prey

The paper is available via the following link:

Please email me on frants.jensen at gmail.com for a pdf copy.

Best regards,
Frants Jensen
----- ----- ----- ----- -----
Frants Havmand Jensen
Associate Lecturer
Scottish Oceans Institute
St. Andrews University
Scotland, UK
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