It is much harder to pinpoint an organisms functional adaptations, as they can easily be proven to be structural or behavioural adaptations. The two most commonly known functional adaptations are a humans response to exercise, such as quickened pulse and sweating to cool down. The other one is a crab's limbs growing back. When a crab loses a limb, such as a leg, they grow back, allowing the crab to continue its living styles without any problem.