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Giant Whales' Mouths Have Unique Nerves: They Stretch
Newly discovered nerves in the mouths of massive whales can unfold, nearly doubling in length, and recoil like a bungee cord. These stretchy nerves could explain how the whales are able to eat by ballooning their mouths during dives.
Researchers discovered the surprisingly elastic nerves after collecting samples from a commercial whaling station in Iceland.
"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, a professor of cell and developmental biology at the University of British Columbia in Canada. [Whale Album: Giants of the Deep]
Rorqual whales represent the largest group among baleen whales, tipping the scales at 40 to 80 tons. They eat by ballooning their mouths, capturing prey and then slowly filtering water out through their so-called baleen plates. The volume of water brought in by a single gulp can exceed the volume of the whale itself.
They're "unrivaled among any vertebrate known alive today," said study co-author Nicholas Pyenson, curator of fossil marine mammals at the Smithsonian's National Museum of Natural History in Washington, D.C. "It's actually a very interesting question, once you get to animals this scale: how do you actually maintain this nervous system?"
The results could even shed light on extinct massive animals, like dinosaurs, the researchers said.
But much about rorqual whales remains a mystery. Their remoteness in the ocean's waters makes them extremely difficult to study. Occasionally, scientists will get their hands on whales that have been beached, but then their tissue has likely already decayed, said Pyenson. Even whales in captivity are less than ideal. More often than not, these whales are unhealthy, and don't represent a typical sample.
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“They live 99 percent of their lives away from the tools of human investigation,” Pyenson told Live Science. “So the question is: How are we going to be able to learn more about them?”
Vogl, Pyenson and their colleagues had the unique opportunity to head down to one of the last commercial whaling stations in Iceland. There, they were able to collect tissue samples (less than 24 hours old) from a dozen harpooned whales. “With every carcass that we examine we find something new,” Pyenson said.
When the researchers first saw the whales' gigantic nerves, no one was sure exactly what he or she was looking at. Because of their stretchiness, the nerves looked like blood vessels at first. In fact, it took years of examining the samples under a microscope before the puzzle finally came together.
Next, the team plans to look at animals genetically related to rorqual whales and other animals of similar size. Pyenson is also especially interested in studying long-necked and long-tailed dinosaurs, known as sauropods. He hopes that better understanding the nervous system in massive whales will shed light on how a sauropod's nerves may have coursed from its chest, along its 50-feet-long (15 meters) neck, to its head.
"I really think we're in a golden age of morphological discovery," Pyenson said. "It's not the kind of science that's necessarily been seen as cutting edge but there's so much to discover. […] We know so much about the context that even little pieces of information like this really enhance our understanding at a very broad scale."
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