Gray's Paradox is a paradox posed in 1936 by British zoologist Sir James Gray. The paradox was to figure out how dolphins can obtain such high speeds and accelerations with what appears to be a small muscle mass. Gray made an estimate of the power a dolphin could exert based on its physiology, and concluded the power was insufficient to overcome the drag forces in water. He hypothesized that Dolphin's skin must have special anti-drag properties.[1]
In 2008, researchers from Rensselaer Polytechnic Institute and the University of California, Santa Cruz used digital particle image velocimetry to prove Gray wrong.[1] They video taped a pair of dolphins swimming through a section of water filled with hundreds of thousands of air bubbles. A computer and force measurement tools developed for aerospace were then used to study the particle-image velocimetry which was captured at 1,000 frames per second (fps). This allowed the team to measure the force exerted by a dolphin. Results showed the dolphin to exert approximately 200 lb of force every time it thrust its tail, (10 times more than Gray hypothesized) and at peak force can exert between 300 to 400 lb.[1]