Mystery Solved: The Power of Dolphin Kicks is Reason for High Speed

Dolphins have a kick that would make Olympic gold-medalist Michael Phelps jealous--96 kilograms worth.

How dolphins are able to swim so fast first preoccupied researchers back in 1936, when zoologist James Gray calculated the drag dolphins must overcome to swim faster than 32 kilometers an hour. Gray said dolphins lacked the muscles to swim so fast, and yet they did. This became known as Gray's Paradox.

Gray theorized that their speed possibly had something to do with their skin. Over the decades, scientists found flaws in Gray's work, and most biologists have rejected his theory.

Now a team of US scientists has used sophisticated underwater video to measure the power of a dolphin's tail. They calculate 96 kilograms of thrust more than triple what a top Olympian like Phelps can produce and enough to swim with the zip that confounded Gray seven decades ago.

"There is no paradox. The dolphins always had the muscles to do this," said Frank Fish, professor of biology at West Chester University in Pennsylvania. "Gray was wrong." ... - phenom

Dolphins can swim at sustained speeds of 20 miles per hour, with burst speeds over 25 mph.