Decapitation or beheading is the total separation of the head from the body. Such an injury is invariably fatal to humans and most other animals, since it deprives the brain of oxygenated blood, while all other organs are deprived of the involuntary functions that are needed for the body to function. Less commonly, decapitation can also refer to the removal of the head from a body that is already dead. This might be done to take the head as a trophy, for public display, to make the deceased more difficult to identify, for cryonics, or for other, more esoteric reasons.