Wily Whales Can Hear Through Their Bones

Using computer simulation of a fin whale head, scientists have discovered that the skulls of at least some baleen whales have acoustic properties that capture the energy of low frequencies and direct it to their ear bones.

Baleen whales, also known as mysticetes, are the largest animals on earth, and include blue whales, minke whales, right whales, gray whales and fin whales.

These whales can emit extremely low frequency vocalisations that travel extraordinary distances underwater.

The wavelengths of these calls can be longer than the bodies of the whales themselves.

"Bone conduction is likely the predominant mechanism for hearing in fin whales and other baleen whales. This is, in my opinion, a grand discovery," said lead researcher and biologist Ted W Cranford from San Diego State University (SDSU).

According to San Diego engineer Petr Krysl, humans experience a version of this phenomenon too.

"We have that experience when we submerge entirely in a pool. Our ears are useless, but we still hear something because our head shakes under the pushing and pulling of the sound waves carried by the water," Krysl noted.

The fin whale skull used for their experiment now resides in SDSU's museum of biodiversity.

It is possible that these new findings will help the governments decide on limits to oceanic man-made noise, but Cranford stressed that what's most important about their project is that they managed to solve a long-standing mystery about a highly inaccessible animal.

"This research has driven home one beautiful principle: Anatomic structure is no accident. It is functional, and often beautifully designed in unanticipated ways," the authors concluded.

All of these whales are considered endangered, with the exception of the gray whale which recently was removed from the endangered species list.

The results appeared in the journal PLOS ONE.