Learning how they make it last through months of scarcity is a worthy lesson in biological belt-tightening. One is to keep working and maintain a high body temperature trying to find food. When hibernators turn in for winter, they also turn down their metabolic rate. That means heartbeat and breathing drop sharply. A reduced metabolic rate, which scientists measure in terms of oxygen consumption, plunges animals into a comatose-like state called torpor.
Many animals are capable of surviving extended periods without breathing at all.
Turtles that hibernate underwater, for instance, can live for three to four months without taking a breath. Hibernating bats consume air rapidly in bouts of panting that last just a few minutes, followed by breathless intervals of up to an hour and a half in length. Scientists who study metabolic suppression don't fully understand what mechanism triggers it or why animals who experience long periods of low body temperature aren't damaged by it. But there is a growing body of theory to explain how and why hibernation works the way it does. Similarily, the bigger the hibernator, the warmer its body temperature during torpor.