This week, researchers at West Chester University in Pennsylvania figured out a novel way to measure just how strong a dolphin is, and solved a 70-year-old puzzle in the process.
In the 1930s, British researcher Sir James Gray timed a dolphin as it swam past his boat at an incredible speed of 33 feet per second, for seven seconds. That's about 23 miles per hour -- other dolphins have been known to speed along at nearly 40 mph, faster than Michael Phelps's top speed of about 4.7 mph. Gray assumed that the dolphin was calming the flow of water, reducing drag. But he couldn't figure out how the dolphin did it. The problem became known as Gray's Paradox.
It turns out there is no paradox: Gray underestimated the dolphin's strength. Dolphins are simply the elite athletes of the sea, ten times stronger than the strongest human athlete. To measure the dolphin's power, the researchers created a "bubble curtain" in the lab by pumping a SCUBA tank through a garden hose, and then let the dolphins go nuts: