Mystery of dolphins' speed solved

bbc. ^ | 25 November 2008

[JoeProBono]

New research has shown how dolphins achieve their blinding speeds. Gray's Paradox - named after British zoologist Sir James Gray - proposed that dolphins simply do not have the strength to swim so fast. But researchers at the Rensselaer Polytechnic Institute in the US have now studied the movement of water around dolphins as they swim. The results show that dolphins can exert as much as 180kg (400lb) of force with their tails...The short answer is that dolphins are simply much stronger than Gray or many other people ever imagined."

[JoeProBono]

Gray had supposed they could produce less than a tenth of this amount, 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 Tim Wei, the Rensselaer scientist who led the study. "The short answer is that dolphins are simply much stronger than Gray or many other people ever imagined." To determine this, Professor Wei used a new method of measuring the movement of water that he originally developed to track Olympic swimmers.

The technique employs digital particle image velocimetry, which measures the speed of water movements around a swimming dolphin or human. Retired US Navy dolphins Primo and Puka were filmed swimming through a tank filled with millions of tiny bubbles. Software tracked the movement of individual bubbles, determining their speed and direction, and assigning them a colour. Professor Wei 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. When "walking" - keeping upright mostly above water with powerful flips of their tails - the dolphins produced as much as 180kg of force. Professor Wei will go on to study the motion and force generation of other sea animals.

[JoeProBono]

[Man50D]

The short answer is that dolphins are simply much stronger than Gray or many other people ever imagined."

No kidding. They actually had to conduct research on something that only requires a little common sense.

[JoeProBono]

Dolphin play bubble rings

[JoeProBono]

Dolphin Dive

[Hot Tabasco]

Phelps vs. Flipper? I'll take Phelps

[JoeProBono]

[skimask]

I have a little tidbit about dolphins I read some years ago. Other than humans, dolphins are the only mammal that have sex for the fun and intimacy of it. All other mammals have sex strictly to pro create.

[JoeProBono]

No fair. Phelps is a fish not a mamal.

[JoeProBono]

[naturalized]

Apparently they had never been to Sea World. Expect research paper on killer whales next.

[thefactor]

jeez, RPI is the main reason Troy, NY is still on a map. with research like this how much longer will this be the case?

i went on a recruiting trip to the school my senior year of high school. the place is over 90% male and the only girls i saw were asian. not that there's anything wrong with that, but these girls weren't really into anything else but school.

needless to say, i did not attend RPI.

[spetznaz]

I have a little tidbit about dolphins I read some years ago. Other than humans, dolphins are the only mammal that have sex for the fun and intimacy of it. All other mammals have sex strictly to pro create.

Actually, Bonobos (Pygmy Chimpanzees) also have sex for fun, and even for favors. Including gay sex (lesbian to be more specific).

[ImJustAnotherOkie]

I believe there is a group of libertine chimps also.

[skimask]

I think that was pointed out to me on thread #13.

[bvw]

That’s good stuff. Cool.

[CholeraJoe]

“So long. And thanks for all the fish.”

[r9etb]

The results show that dolphins can exert as much as 180kg (400lb)

Sigh.... Force = Newtons. 400lb = 1779 N