On the grasslands of the world, there is a premium on speed. The lack of dense vegetation or large bodies of water allows animals to run across this landscape without being slowed down. Natural selection favours those predators that are fast enough to catch food, and those prey animals that are fast enough to escape. The arms race between hunted and hunter is a ferocious one, with different species furiously evolving to stay, literally, one step ahead of the competition.
The fastest of them all is the cheetah. Very few production cars can reach 60mp/h faster than a cheetah. None can do it on grass.
Born to Run
Everything about the cheetah’s body is built for speed. It has ridged pads on its paws and semi-retractable claws that maximise traction with the ground and prevent the animal from slipping during sharp corners. Flared nostrils allow maximum oxygen intake during a chase, while a huge heart and huge lungs keep the oxygen flowing to the muscles where it is so desperately needed. Its incredibly flexible spine flexes to increase stride length; its long tail acts as a counterweight, maintaining balance during sudden turns. The black ‘tears’ under its eyes cut down glare from the sun as it runs, and it has a wide, super-sensitive stripe on its retina that gives exceptional focus across its entire field of vision. All of these adaptations enable a cheetah to accelerate from a standing start to 60 mp/h in just three seconds, and it can reach a top speed of just over 70mp/h.
But the speed must come at a price. A cheetah can only run at its top speed for around 30 seconds, during which it skirts dangerously close to oxygen deprivation. If it ran for much longer, there would be a huge build up of lactic acid within its body, causing painful cramps. Its body temperature during these short sprints rises to an almost lethal 40.6°C – any higher and the animal would suffer brain damage. If a cheetah isn’t close to catching its prey within that half a minute time limit, it will abandon the chase. It may have to rest for half an hour or more to recover and pay back its extensive oxygen debt.
Even if a cheetah does catch its prey, which it usually dispatches by tripping it up and then crushing its windpipe, it cannot immediately eat its meal. It must rest after making a kill to recuperate after the exhausting chase, and this gives scavengers such as hyenas plenty of time to arrive and steal its kill. The cheetah will not fight another animal for ownership of its meal. Its body is too lightweight and fragile to be of any real use in a fight and it will not risk damaging its perfectly adapted body. Just a single injury could deprive the cheetah of its only advantage – its speed – and that would lead to its doom.
The price for such extreme speed is high and almost insurmountable. The cheetah only just manages to get over them.