According to Gray’s paradox, dolphins swim faster than they should be able to. Since Gray, scientists have discovered flaws in the details of the paradox, although some explanations of these creatures’ aquatic grace have proven to hold more water than others.

Since the days of Aristotle, humans have looked to dolphins with awe, envy and inspiration because of the marine animal’s speed and strength in the oceans. Swimming at speeds of up to 20 mph, the dolphin seems to defy nature’s laws. In fact, in the 1930s, the scientist James Gray thought that the power needed for the dolphin to swim at such speeds exceeded its available power nearly 10 times over, which is known as Gray’s paradox.

To explain his paradox, Gray theorized that the water against the dolphin’s skin has layers that slide past each other and reduce drag, called “laminar boundary layers.” (It was previously assumed that the water against the skin was made of several mixed layers that increase drag, called “turbulent boundary layers.”) In actuality, no mechanisms have been demonstrated that maintain a completely laminar boundary layer for the dolphin.

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