What makes the fastest animals in the world the fastest?

Answer 1

Each fast animal has adaptations specific to its environment and to the type of action they're performing. Cheetahs being the fastest land animal, have narrow ribcages, long legs, and small heads for aerodynamics. Their tails act as a counter-balance when making quick turns; their paw pads are rigid and have blunt, non-retractable claws; they have a flexible spine that gives them a fuller range of motion, acting like a spring, to create a 25 foot stride at top speed. They even have smaller jaw muscles to accommodate their larger nasal passages that enable them to bring enough air into their huge lungs. Everything about the cheetah is designed for speed in a relatively flat and barren landscape.

Peregrine falcons have different adaptations, but basically, again it comes down to anatomy. Peregrine falcons have huge flight muscles that can more efficiently move oxygen through the bloodstream--this means that they can fly longer without fatiguing. Their feathers are streamlined and stiff so they reduce drag. The shape of the wings enables peregrine falcons to dive at speeds nearing 200mph, and sustain flight at speeds between 60-70mph.

Like I said before--with most fast animals it's all about their anatomy in relation to their environment.