Huge Whales Boast Unique 'Bungee Cord' Nerves
Baleen whales are indisputably huge creatures and rorqual whales are the largest group of them all, weighing up to a stunning 180 metric tons. Even the smallest of this group, the northern minke whale, can weigh a whopping 9.9 short tons. Being so big, it's not a stretch to assume their biology might be a little different than our own, and now a new study has proven it so. Rorqual whales, it seems, have unique nerve tissue that is just as thick and stretchy as your run-of-the-mill bungee cord.
"This discovery was totally unexpected and unlike other nerve structures we've seen in vertebrates, which are of a more fixed length," Wayne Vogl, a researcher with the University of British Columbia's cellular and Physiological Sciences Department, explained in a statement.
"The rorquals' bulk feeding mechanism required major changes in anatomy of the tongue and mouth blubber to allow large deformation," he added, "and now we recognize that it also required major modifications in the nerves in these tissues so they could also withstand the deformation."
What Vogl is talking about is the intriguing way in which baleen whales feed. Think of your traditional baleen whale as a massive vacuum. Opening its gaping maw as wide as physically possible, a whale will let a stunning portion of its body fill up with water, stretching its mouth and insides to the fullest extent of their impressive elasticity. Then the whale seethes that scooped water out through its iconic comb-like tooth plates (baleen), leaving only heaps of tiny prey like krill, copepods, and even small fish to be swallowed. (Scroll to read on...)
To account for that impressive elasticity, the whales' mouths must boast structural changes not seen in true toothed whale varieties, and these 'bungee-like' nerves are just another adaptation to add to the list.
Comparatively, in humans, over-extending nerves usually damages them. For rorquals, however, the nerve cells are packaged inside a central core in such a way that the individual nerve fibers are never truly stretched; they simply unfold.
The researchers now hope to further investigate how these nerve systems fold and unfold so efficiently.
"This discovery underscores how little we know about even the basic anatomy of the largest animals alive in the oceans today," added Nick Pyenson, of 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."
The findings are detailed in the journal Current Biology.
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