Why do cats almost always land on their feet?

Cats have an exceptional righting reflex that develops at around three to four weeks of age. Their very flexible spine, with 30 vertebrae compared to a human’s 24 in the spinal column, lets them twist the front and back halves of their body independently. They tuck in their front legs (reducing rotational inertia) to spin the front half first, then extend them and tuck the back legs to spin the rear half. The whole manoeuvre can happen in under a third of a second. Their low body-to-weight ratio and ability to spread out like a parachute also help reduce impact. Despite this, cats can still be seriously injured in falls.