Hibernation is derived from the Latin hibernare which means “to pass the winter”. Hibernation is a state of greatly reduced metabolic activity. It refers to a season of heterothermy characterized by low body temperature, slow breathing and heart rate, and low metabolic rate. It is most commonly observed during the winter months. 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 rather than any absolute decline in body temperature.
Often associated with low temperatures, hibernation functions to conserve energy when sufficient food is unavailable. To achieve this energy saving, an endothermic animal decreases its metabolic rate and thereby its body temperature. It may count as days, weeks, or months depending on the species, ambient temperature, time of year, and the individual’s body condition. Before entering hibernation, animals need to store enough energy to last through the duration of their dormant period, possibly as long as the entire winter. Larger species become hyperphagic, eating a large amount of food and storing the energy in fat deposits. In many small species, food caching replaces eating and becoming fat.
For example:- Female polar bears go into hibernation during the cold winter months in order to give birth to their offspring. The pregnant mothers significantly increase their body mass prior to hibernation, and this increase is further reflected in the weight of the offspring. The fat accumulation enables them to provide a sufficiently warm and nurturing environment for their newborns. During this period they subsequently lose 15–27% of their pre-hibernation weight by using their stored fats for energy.
1. Bats Hibernation
In winter, bats go into hibernation. Hibernation is an extended period of deep sleep called as torpor, that allows animals to survive cold winters with harsh weather. A bat’s body temperature lowers and their metabolic rate slows, meaning they use less energy and can survive on the fat they have stored up instead of trying to forage for food. During hibernation, bats need roosts that are cool and remain at a constant temperature. They often move into underground sites, such as caves.
2. Fat-tailed dwarf lemurs
Hedgehogs are some of the deepest hibernators around. Some can sleep through the whole winter! Their body temperature drops and they breathe so little that it can hardly be seen. They have special cells that release heat 20 times faster than white cells. If temperatures drop too low, their heart beat picks up to produce more heat, which wakes them up briefly before they fall asleep again.
8. Snails Hibernation
Snails have a built in bed for their hibernation. They go into their shell, close up the hole with a skin made of chalk and slime that keeps the moisture in. During this time, they use almost no energy and don’t have to eat anything at all. In some areas where there is little rain, snails can hibernate for years.