How do animals hibernate?

Hibernating animals can be roughly divided into two categories, one is amphibians and reptiles. Amphibians and reptiles, such as frogs, snakes and turtles, are warm animals. When the weather is cold, they can't move and go into hibernation.

The other is mammals. Mammals are divided into bear type and squirrel type. Most hibernating animals consume pre-stored fat (equivalent to 30%-40% of their body weight) as energy during hibernation. When the outside temperature drops, they will lower their body temperature. Reduce pulse and breathing times to save energy. However, the temperature of hibernating bears does not drop much, and it remains at 38℃ or 30℃. Why? It turns out that bears are huge, and it takes a long time to recover their body temperature after their body temperature drops. In addition, the bear has a "trick" that doesn't need to save energy so much. In other words, it never excretes during hibernation. If urine is excreted, nitrogen compounds will be excreted, and the bear will not urinate, but will be absorbed by the kidney wall, and then the anti-nitrogen compounds will be reused as nutrients. Now some scientists have noticed this "trick" of the bear and are exploring how to use it to treat human kidney diseases.

So, do small mammals and squirrels also have this "trick"? Unfortunately, they didn't. Some animals of this type need to dig holes in the ground to build a nest that can safely accommodate their bodies during hibernation, so their weight is not big, only 9 kilograms at most. Animals such as bats should "get up" from time to time and excrete feces and urine. But like bears, they first store enough fat as energy, so they don't eat or drink during hibernation. Occasionally, they are found to store food, but that is to prevent them from starving when they wake up from hibernation prematurely in spring.

However, voles and other animals are still inseparable from food during hibernation. They get up and excrete every 10 day during hibernation, then eat some food and go back to sleep. Their body temperature will drop from 37℃-38℃ to 8- 10℃, and some will even drop to-1.5℃.

What if the temperature is too low during hibernation? Generally, because they hibernate underground, it is difficult for the temperature to drop below 0℃, but if the temperature drops to about-10℃, they will get up and shake their muscles and generate heat. However, if they have to do that, they will consume their physical strength, so they should be very careful when choosing the hibernation place, and should consider it in many ways, not too cold or too hot.