Born to Run
art by Leslie Evans
If a cheetah and a horse ran a 100-meter dash, who would win? The cheetah—it's the fastest land animal in the world and can run as fast as 70 miles per hour. Even the fastest racehorses reach speeds of only about 45 miles per hour. But if a cheetah and a horse ran a mile race, who would win? The horse—the cheetah would have to stop less than halfway through to rest and catch its breath. The horse, however, could keep running for miles without tiring. It's built not only for speed but also for endurance.
The horse's large lungs and heart pump oxygen-rich blood throughout its body. The oxygen provides energy for speed and stamina.
A long neck is not just beautiful, it helps balance the horse while it's running.
Like a person, a horse sweats when it runs, cooling off large areas of skin quickly. Cats and other animals with thick fur cool off by panting. If a horse cooled itself that way, its body temperature would rise so high when it ran that it would have to stop running or it might die.
Can you sleep standing up? A horse can because its legs can lock into place when it stands. It doesn't need to get up; it's always ready to run.
The horse's long legs enable it to take big strides, covering lots of ground with each step. Its leg is stretched out so that the parts under its body actually correspond to a human leg from the knee down. This lower leg is strong but lightweight to swing back and forth quickly. The horse's heavy thigh and hip muscles, which provide power, are up by its tail.
The horse's foot is very flexible. It flattens and stretches like a spring to propel the horse forward.
A horse runs on tiptoe. Each leg ends in one long, strong toe covered with a hard hoof. The hoof wall is like a human toenail, and nailing a metal shoe to it hurts no more than cutting a toenail. The shoe protects the hoof from hard use on paved roads but doesn't interfere with the frog, an elastic cushion that serves as a kind of shock absorber, softening the impact when the hoof hits the ground.
- What activity has a horse's body adapted to do?
[anno: The horse's body is adapted to run.]
- How has the horse's body adapted to do this?
[anno: The horse sleeps standing up. It has a large heart and lungs. It has long legs and a long neck. The horse has large nostrils. The horse has flexible feet.]
- Why do you think the horse has adapted to do this activity?
[anno: Answers may vary but could include that the horse is a prey animal and thus has to outrun predators to survive.]