A Baleen Whale Skull Conducts Sound 'Like An Acoustic Antenna'

Illustration for article titled A Baleen Whale Skull Conducts Sound 'Like An Acoustic Antenna'

Researchers used computer models and high-powered simulations to confirm that whales' skulls have evolved to act "like an acoustic antenna," amplifying and transmitting low-frequency sounds (hypothesized to be important in long-range communication) toward the ears.


Above: Left lateral view of the skull bones in a fin whale, via Cranford and Krysl

Erin Blakemore describes how San Diego State marine biologist Ted W. Cranford and UC San Diego structural engineer Petr Krysl modeled the acoustic properties of whale skulls, for Smithsonian Magazine:

Krysl and Cranford obtained the skull of a young but ill-fated beached fin whale and put it in a scanner originally designed for rocket motors. They used their scan to make a model that broke the anatomy down into Lego-like blocks, then mapped the relationships between each tiny element.

When they sent sound waves through their simulated skull, they could see how each little bone segment vibrated. But they weren't done yet. Since the skull they modeled was that of a juvenile whale, they made another model that was three times as big. Then they had to find a computer that would actually be able to process the immense amount of data generated by their simulations.

Using a supercomputer, Cranford and Krysl ran their simulations for days, even weeks at a time. And it led to what Cranford has called "a grand discovery"—whale skulls seem to conduct sound, amplifying waves as they hit the skull and passing them along to the ear bones.

"The entire surface of the animal's head receives sound, and the anatomy channels the sound toward the ears," summarize Krysl and Cranford, in the open access journal PLOS ONE.

I love whales. They're fantastically weird animals. Paleobiologist Nick Pyenson, who in 2012 helped discover a grapefruit-sized sensory organ located in the chins of a subset of baleen whales known as rorqual whales, calls them "mammals from space." With Krysl an Cranford's study, these space mammals just got a little weirder.



I'm glad they have more official proof. It's kind of like a Weber and Rinne test you do on people to see if there's conductive or sensorineural hearing loss. The whales' whole head is basically a resonancy amplifier, where humans only have our mastoid processes and tympanic bones to help us.

If you really want to try and convince people that evolution is real, comparative anatomy is a dang good way. Beautifully instructive. Darwin really was a genius.