Cat righting reflex

The cat righting reflex is a cat's innate ability to orient itself as it falls in order to land on its feet. The righting reflex begins to appear at 3–4 weeks of age, and is perfected at 6–9 weeks. Cats are able to do this because they have an unusually flexible backbone and no functional clavicle (collarbone). The tail seems to help but cats without a tail also have this ability, since a cat mostly turns by moving its legs and twisting its spine in a certain sequence.