Why can some animals hibernate, but their bodies are not hungry, and they can move again after a few months?

Hibernating creatures are mostly reptiles, and blood animals have slow metabolism, so they will not be particularly hungry after sleeping for several months. Only a few mammals store food or eat a lot of fat before hibernation, and live on food or fat when they are hungry.

A serious problem that multicellular animals need to face is body temperature, and their own cells need to live at a suitable temperature, because the activities of cellular enzymes need a certain temperature. Enzymes are mostly protein or RNA in nature, which will be inactivated at higher temperature and their activity will decrease in lower environment, so multicellular organisms need to keep their body temperature.

The temperature regulation of cold-blooded animals is completely different from that of warm-blooded animals. Cold-blooded animals can't actively regulate their body temperature, and they need to rely on natural heat sources such as sunlight and hot springs to keep their body temperature. Most of the time, their body temperature is relatively low, and their heartbeat and other activities are also relatively low, which will lead to the decrease of biological and physiological activities. Therefore, the physiological activities of cold-blooded animals are generally weak and can maintain more energy. However, in winter, low temperature will lead to a sharp drop in body temperature, which will lead to the failure of normal physiological activities and lead to death.

Because cold-blooded animals do not need to actively maintain their body temperature, they consume less energy and eat less times. On the other hand, warm-blooded animals are different. The energy in the food you eat is transported to the cells for energy supply. When cells oxidize substances such as sugar, they will generate a certain amount of heat, and a constant body temperature can ensure that physiological tissues have sufficient activity.

Warm-blooded animals are usually creatures with developed brains. Hypothalamus has a thermoregulatory center, which can maintain body temperature by regulating blood volume. After all, the tissues and organs of multicellular organisms need oxygen and nutrients transported by blood to survive. This makes the biological heartbeat frequency relatively high, which is also the reason why the heartbeat will slow down when the body temperature drops, but also because of this factor, warm-blooded animals consume energy relatively quickly and have higher requirements for eating frequency.

So most hibernating creatures are cold-blooded creatures and insects, while warm-blooded mammals lack such ability. Cold-blooded animals usually hibernate in crypts. The crypt itself is relatively closed, isolated from the external environment and underground, so the temperature can be slightly higher. During hibernation, the heartbeat and respiratory rate of cold-blooded animals are reduced again, and their physiological activities are minimized. At this time, cold-blooded animals can better conserve energy in their bodies, and make maximum use of energy to maintain the most important physiological activities such as heartbeat and breathing, so that cold-blooded animals can hibernate most of the year and concentrate their activities in summer.

Warm-blooded animals can't, because they eat more frequently and because they need more energy to maintain their body temperature. There are usually two kinds of mammals that can hibernate. One is small animals like squirrels. They will prepare a lot of food before the arrival of winter, so that they don't have to go out for food in winter, reducing the chance of being hunted and the risk of starvation.

One is a large species like bears, which mainly stores fat. Fat itself is transformed from excessive sugar and fat intake. When food is scarce, fat will also be converted into energy. Humans also have this ability, so they will be hungry for a long time, but bears will go further. They will actively store fat before the arrival of winter, which can be converted into energy in winter, so that they can resist hunger for a longer time. But the bear is not afraid of the cold. It's just that animal activities are reduced in winter, so it's not cost-effective to go out hunting, so he just sleeps.

Humans are also warm-blooded animals, which do not have hibernation ability and have a high energy consumption rate. They eat three or two meals a day. There are basically no creatures in the animal kingdom who can eat and drink at will like humans, because humans know how to produce food by feeding, which greatly enriches the material. Now humans are also studying the methods of hibernation, probably because they have to face problems such as interstellar migration. When they hibernate, their physical activities will be reduced, which can relatively reduce their own consumption and make people live longer, but they still can't.