Cheetah

The chase lasted less than 30 seconds. No jagged turn could throw the hunter. Through the grasses and over the scrub, the cheetah tailed the impala at every turn and dogged its prey at every corner. And then, in an instant, it was over—under the heat of the savannah sun in northern Botswana, the cheetah feasted in victory. But here's what's truly impressive: The cheetah, the fastest land animal on the planet, only needed to reach half its top speed.

Alan Wilson, a researcher of biomechanical movement at the University of London, led a study that appeared in today's Nature in which his team used GPS collars to detail the first-ever measurements of turning speeds and acceleration in cheetahs. Any kid who stayed awake in science class probably remembers that cheetahs are the fastest land animals, but, Wilson says, most successful hunts had little to do with flashy top speed. "Acceleration and deceleration are absolutely critical," Wilson says. "It's turning, maneuvering, and changing speed that's needed to get close enough to the prey to actually capture it."

Cheetahs use their nonretractable claws and rigged footpads as cleats to maximize their traction, and avoid burnouts when turning by shifting their heavy tails. Those skills, combined with enormously long hamstring and calf muscles, help cheetahs take home the gold as the fastest-accelerating land animal, in addition to having the highest top speed. In a single stride cheetahs can tack on an extra 7 mph, and at their peak the big cats accelerate at a rate of slightly more than 1 g—meaning they accelerate at roughly the speed of a falling rock. Greyhounds, the second-fastest land accelerator, can post about 0.7 g's.

But if you really want to see impressive acceleration, get off the land.