Michael Phelps, the 23-year-old Olympic swimmer, has captivated the world with his quest to win eight gold medals in a single Olympics. With every race he wins, Phelps draws closer to surpassing the record seven golds Mark Spitz captured in the 1972 Munich Games. While Phelps’s teammates reportedly call him “squid boy,” many awed spectators and commentators have dubbed him “the human dolphin” — a moniker that’s marginally more flattering (at least there are no tentacles involved). But does the name really fit?

With flipper-like feet that purportedly fill size 14 shoes, it may be tempting to make the comparison, but let’s take a look at the raw numbers. On August 12, Phelps broke the World Record time in the 200-meter freestyle, clocking in at 1:42.96. That works out to a speed of about 7 kilometers, or 4.35 miles, per hour. And that assumes he could maintain such a speed over longer distances — not likely.

Let’s be honest. Compared to the bottlenose dolphin’s top recorded speed of about 30 miles per hour, Phelps is more like a sea snail. Even at their normal speed of about 20 miles per hour, a family of dolphins would leave this Olympian in a cloud of bubbles.

On other measures of aquatic excellence, Phelps similarly comes up short. Take for instance his celebrated ability to “sense” his position in a pack of competitors. But can he compete with a dolphin’s sophisticated system of echolocation? I don’t think so.

So who’s the real master of the water? Well, if you expand the search beyond marine mammals, the answer might be billfish. Sailfish have been recorded swimming at an astonishing 68 miles per hour over short distances.

While Michael Phelps may be the fastest human in the water, don’t forget to look to nature for amazing creatures that are really “born to swim.”

On NATURE:

• The Dolphin Defender
• Superfish