The secret to a dolphin’s speed is sheer strength, according to a new study that used high-tech measurements to finally put a 70-year-old conundrum to rest. In 1936, British zoologist James Gray incredulously observed dolphins swimming at speeds of over 20 mph. He estimated that the dolphins should only be able to produce a tenth of the necessary force and imagined that something about the dolphins’ skin allowed them to overcome the force of drag in the water and reach high speeds. “For the first time, I think we can safely say the puzzle is solved,” said [researcher] Tim Wei…”The short answer is that dolphins are simply much stronger than Gray or many other people ever imagined.” [BBC News].
Although most biologists had long rejected what became known as Gray’s Paradox, there has never been a study to determine the strength of a dolphin’s kick. To observe the powerful swimmers up close, researchers recruited two retired U.S. Navy dolphins, Primo and Puka, to swim in a specially designed tank filled with tiny bubbles that make the movement of water visible. The tank was too small to capture video of the dolphins at full speed, so they also videotaped them performing tail stands on the water (think Sea World). The thrust was calculated based on the dolphins’ weight and measurements of the wake created by their tails [AP].
Using software that tracked the rush of bubbles, the researcher then used force measurement concepts from aerospace research to translate those velocities into a force that the dolphins’ tails were producing – nearly 100kg (200lb) on average [BBC News]. That amount of thrust is about six times that of an average Olympic-level swimmer and more than triple that of swimming phenomenon Michael Phelps. Without similar muscle mass, even the the new Speedo LZR Swimsuits wouldn’t give Phelps an edge over Flipper. “There is no paradox. The dolphins always had the muscles to do this,” said Frank Fish, professor of biology…. “Gray was wrong” [AP].
Wei presented his findings at yesterday’s American Physical Society conference. He plans to use similar setups to investigate flow dynamics and force generation of other marine animals, which could offer insight into how species evolved because of their swimming proficiency [UPI].
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Image: flickr / Captain DJ
November 27th, 2008 at 1:42 pm
I hate to be crass (I think I say this a lot) but “duh.”
Dolphins are born in the water and then proceed to spend nearly every moment from that point until they die swimming. They don’t even stop to sleep (last I read, science had determined they put half their brain to sleep for short periods but stay awake with the other half, so they wont drown). Imagine a human who’s ran nearly 24/7 every day of their lives, and imagine how much faster they’d be than a regular human when the time came to race. Their muscles would be bigger and their bones would be stronger from the constant unrelenting exercise.
Get Phelps some hand webbing and some of those flipper that cover the tops of your feet and shins to enhance your natural kicking motions and then we’ll see how fast he can go, seeing as dolphins also have a slight aerodynamic and large thruster-surface advantage over humans in the water.
November 29th, 2008 at 4:07 pm
Um, it helps to be descended from many thousands of generations of ancestors who also had to be good enough at those things to live long enough to reproduce, too. Enough iterations of that process gets you something like a dolphin.
Phelps obviously doesn’t have that going for him, either. The playing field will never be (sea?) level.
February 15th, 2009 at 1:31 am
hi that was borning i will tell you agina?