Hibernation. Hibernation is a state of inactivity and metabolic depression in endotherms.
Hibernation refers to a season of heterothermy that is characterized by low body temperature, slow breathing and heart rate, and low metabolic rate. Although traditionally reserved for "deep" hibernators such as rodents, the term has been redefined to include animals such as bears and is now applied based on active metabolic suppression [1] rather than based on absolute body temperature decline. Cryptobiosis. Cryptobiosis is an ametabolic state of life entered by an organism in response to adverse environmental conditions such as desiccation, freezing, and oxygen deficiency.
In the cryptobiotic state, all metabolic processes stop, preventing reproduction, development, and repair. An organism in a cryptobiotic state can essentially live indefinitely until environmental conditions return to being hospitable. Suspended animation. Suspended animation is the slowing of life processes by external means without termination.
Breathing, heartbeat, and other involuntary functions may still occur, but they can only be detected by artificial means. Extreme cold can be used to precipitate the slowing of an individual's functions; use of this process has led to the developing science of cryonics. Cryonics is another method of life preservation but it cryopreserves organisms using liquid nitrogen that will preserve the organism until reanimation.