Whale blubber as an acoustic receiver

From: Pete Scheifele (scheifel@uconnvm.uconn.edu)
Date: Fri Dec 15 2000 - 10:23:27 EST


 So happy to be of service (I think). Regarding your latest inquisition:

No, I doubt that blubber makes the whole animal act as a large receiver by
helping to receive/amplify
signals sent from other whales. In the case of Mysticetes reception is via
the ears and production (not well known) from the head. In Odontocetes we
see a different evolution where active signals are developed by the
premaxillary sacs and emitted via the nasal plugs beneath the blowhole or
via the melon for echolocation. Reception is via the lower jaw. In the
case of Odontocetes both the melon and lower jaw have evolved to conatain
isovaleroyl-rich tissues that result in considerably lower transmission
sound speeds compared to normal marine adipose tissue composed of
long-chain unsaturated acids. Typical blubber lipids transmit sound at a
higher velocity than isovaleroyl lipids. Sound passing across a fat/water
interface is refracted and, combined with the possession of a fat deposit,
which has its own low sound velocity core and whose shape can be altered,
it is concievable that the structure can focus sound waves passing through
it. This is routinely copied by engineers n the construction of
transducers. In the lower jaw these lipid-rich tissues are excellent
conductors of sound, having a low impedance with respect to seawater. Once
again, the nature of the isovaleroyl and longer-chained lipids suggests a
"biochemical zonation" which could be construed as a "focusing" mechanism
for sound reception.

Have sparkling day.

Peter "Skip" Scheifele

Peter M. Scheifele LCDR USN (Ret.)
Director of Bioacoustic Research
NURC Operations Manager
Director of Marine Education Programs
National Undersea Research Center,
North Atlantic and Great Lakes
University of Connecticut
860-405-9121/9103 (Voice)
860-445-2969 (FAX)
scheifel@uconnvm.uconn.edu / acousticp2@juno.com

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