Scientists have discovered a unique nerve structure in the mouth and tongue of giant whales that can double in length and then recoil like a bungee cord to help them hunt for fish.
The stretchy nerves explain how the massive rorqual whales are able to balloon an immense pocket between their body wall and overlying blubber to capture prey during feeding dives.
"This discovery was totally unexpected and unlike other nerve structures we've seen in vertebrates, which are of a more fixed length," said Wayne Vogl of University of British Columbia (UBC)'s Cellular and Physiological Sciences department.
"The rorquals' bulk feeding mechanism required major changes in anatomy of the tongue and mouth blubber to allow large deformation, and now we recognise that it also required major modifications in the nerves in these tissues so they could also withstand the deformation," said Vogl.
In humans, stretching nerves usually damages them. In these whales, the nerve cells are packaged inside a central core in such a way that the individual nerve fibres are never really stretched, they simply unfold.
"Our next step is to get a better understanding of how the nerve core is folded to allow its rapid unpacking and re-packing during the feeding process," said UBC zoologist Robert Shadwick.
Researchers don't know yet whether anything similar will turn up in other animals - the ballooning throats of frogs, for example, or the long and fast tongues of chameleons.
"This discovery underscores how little we know about even the basic anatomy of the largest animals alive in the oceans today," said Nick Pyenson, a UBC postdoctoral fellow currently curator of fossil marine mammals at the Smithsonian's National Museum of Natural History.
"Our findings add to the growing list of evolutionary solutions that whales evolved in response to new challenges faced in marine environments over millions of years," said Pyenson.
Rorquals are the largest group among baleen whales, and include blue whales and fin whales.
The findings were published in the journal Current Biology.
