Just two months after physicists proved a century-old invention by Nikola Tesla works better than anyone realised it turns out someone else got there first, by a few hundred million years. 3D images of shark intestines show they use Tesla’s technique, apparently for most of the time they have ruled the oceans.
Sharks innards have often been examined to learn if they had anything to do with somebody’s one way trip into the ocean, or more exotic demise. However, this is much more convenient after the shark is dead, leaving zoologists little opportunity to see how the intestines operate when the shark is alive. "Intestines are so complex, with so many overlapping layers, that dissection destroys the context and connectivity of the tissue,” said Professor Adam Summers of the University of Washington in a statement. “It would be like trying to understand what was reported in a newspaper by taking scissors to a rolled-up copy. The story just won't hang together."
Dr Samantha Leigh of California State University, Dominguez Hills sought to go beyond flat sketches of expired sharks’ innards and published her results in Proceedings of the Royal Society B. "It's high time that some modern technology was used to look at these really amazing spiral intestines of sharks," Leigh said. "We developed a new method to digitally scan these tissues and now can look at the soft tissues in such great detail without having to slice into them."
The method required CT scans but wheeling a shark into a hospital might raise eyebrows, Fortunately Summers’ lab has one, used to reveal many animals’ innards.
Leigh and Summers concluded spiral-shaped organs in sharks digestive system slow the movement of food through giving sharks more time to scavenge nutrients while requiring less energy to do so. Like many apex predators, some sharks consume very large meals but then can go a long time between feeds.
A digestive system that uses the intervening time well is a major asset, one that presumably helped sharks not only fight their way to the top of the food chain, but survive mass extinctions that wiped out many formidable competitors. Similar structures were found within representatives of 22 families of sharks, rays and skates, and appears independent of diet, indicating the structure dates back to the very origins of Selachimorpha.
A combination of gravity and rhythmic gut muscle contractions to force food in the direction it needs to go, while the spirals prevent its return during any sudden maneuvers. These operate in a similar manner to Tesla’s valve, which pushes fluids in one direction while preventing their movement the other way.
Like many of Tesla’s other inventions, the valve was largely ignored when first patented. He had, after all, many great failures along with his immense feats in engineering. However, as Tesla’s status has grown his “valvular conduit” has achieved an online cult following, with its harnessing of turbulent flows only recently attracting scientific explanation. That discovery was accompanied by the suggestion the Tesla’s Valve might have overlooked applications, and it seems the sharks were way ahead of us.
The intestines could act as an inspiration for some novel uses for Tesla Valves, such as wastewater treatment mechanisms that maximize pollutant removal. "We need to look harder at sharks and, in particular, we need to look harder at parts other than the jaws, and the species that don't interact with people." Summers said.
A live Pacific spiny dogfish shark (Squalus suckleyi). Who would have guessed what lies within. ImageCredit: Samantha Leigh/California State University, Dominguez Hills
5