Lemmings Lemmings are the most widely distributed herbivores in the Arctic, and the nature and mystery presented by this small animal are puzzling. 1. The mystery of super reproduction of lemmings Lemmings is the most fertile of all animals in the Arctic. They can give birth to 7-8 cubs a year, and each cub can give birth to 12 cubs. It only takes more than 20 days for the cubs to mature and start giving birth. Let's calculate its reproductive capacity: if a pair of lemmings start to give birth in March, if they give birth to seven babies a year, each baby will have 12, a total of 84. This is their second generation, which is their son and daughter. Suppose each fetus is 6 males and 6 females, that is 6 pairs. Twenty days later, six pairs of the first child began to be born, each pair 12, and 72 pairs were born at once, making a total of six pairs, which is 432 pairs. Forty days later, six pairs of the second child also joined the birth army. They can have five children altogether. If each child has 12, it is 360. By analogy, then, how many grandchildren can they have? There can be 15 12 in total. This is the third generation. Don't forget that 40 days later, 36 pairs of third-generation firstborn babies began to breed, and their firstborn babies could give birth to 432, a total of 5 babies, which is 2 160. There are also the second to seventh births of the third generation, so the fourth generation can give birth to 6480 mice. According to this calculation, the fifth generation is 25920, the sixth generation is 933 12, the seventh generation is 279936, and the eighth generation is 559872, which is the last batch this year. You see, from two in March to the end of August and the beginning of September, it has become a huge team of 967 1 18! Because of climate, disease and natural enemies, half of them died halfway, almost 500 thousand. The density can reach as many as 250 per hectare. This is the first mystery of lemmings. 2. The mystery of lemmings' self-exposure When the number of lemmings expands rapidly and reaches a certain density, for example, there are hundreds of lemmings in a hectare, a strange phenomenon will happen: at this time, almost all lemmings suddenly become restless, and they run around, making noise and stopping eating, as if disaster is imminent and the end of the world is coming. At this time, lemmings are no longer timid and run away from everyone. Instead, they are brave and fearless in front of any natural enemies, obviously provocative, and sometimes even take the initiative to attack, which is really a bit fearless. What is more difficult to explain is that at this time, even their skin color will change obviously, from gray-black to bright orange-red, which is particularly prominent. All these strange phenomena together, the only possible and reasonable explanation is that they are no different from suicide, and they are all aimed at attracting the attention of natural enemies such as owls, skua, gray-black seagulls, thick-legged vultures, arctic foxes and even polar bears, so as to devour them more. This is the second secret of lemmings. 3. The mystery of the great migration of lemmings lies in the fact that there are too many lemmings and the number of natural enemies is always limited. No matter how you expose yourself, the effect is not great. So they will show a very strong sense of migration, gather together and gradually form a large group. At first, they seemed to have no direction and goal, and they ran around like they were in a hurry, making preparations before departure. But later, I don't know who gave the order or who took the lead, but they suddenly set off in the same direction. I often rest and eat during the day and go forward in the dark at night. Rats are constantly joining along the way, and the team will get bigger and bigger, often reaching millions. They will cross the mountains, wade through the water, go forward bravely, go to the sea without detours and stops, still fearless, and jump down one after another until they are swallowed up by the raging waves and wiped out by the whole army. This is the third mystery of lemmings. An American article entitled Sandnes and Heroic Sacrifice in the Sea-Towards the Covenant of Death became popular on the Internet, and was transferred from the Reader's issue 15 in 2005. It is said that a Norwegian cancer patient had an epiphany while following lemmings to death: there is no need to be afraid of death, because life and death are both part of life. However, judging from the content and writing style, it is not like a translated work, but a fake work by domestic writers, which vividly depicts the scene of millions of lemmings jumping into the sea and committing suicide after a long journey for the benefit of species. In fact, it is adapted from a popular science article introducing China's "Lemmings Mystery". Legend has it that when the number of lemmings reaches its peak, they will spontaneously migrate collectively and commit suicide in the sea, leaving only a few similar people behind to undertake the sacred task of carrying on the family line. In the documentary "White Wilderness" filmed by Disney in 1958, the lemmings migrated in groups and finally committed suicide by jumping into the sea, with very sensational explanations. This Oscar-winning film has far-reaching influence, and the touching legend that makes lemmings go to the death Covenant is well-known in the west. But the scene of that documentary was faked. The film was shot in Alberta, Canada, where lemmings are not produced. The photography team went to the North Pole to buy dozens of lemmings from Inuit children, let them run on a turntable covered with snow, shoot from all angles, and after editing, thousands of lemmings migrated. After that, the film crew took the lemmings to the edge of the cliff, hoping to film them jumping into the river under the cliff and drowning. Unexpectedly, lemmings didn't want to jump. After waiting for two days, the impatient photography team drove the lemmings off the cliff and committed suicide by jumping into the sea. Why the number of lemmings changes periodically is an inconclusive biological topic, which may be related to natural enemies, food, climate, seasons and other factors. For example, an obvious but unconfirmed explanation is that the rapid increase in the number of lemmings destroyed the vegetation, resulting in food shortage and a large number of lemmings starved to death. Then the vegetation began to recover and a new cycle appeared. In fact, this phenomenon is not unique to lemmings. Other small animals living in harsh conditions will have similar periodic changes in their populations. Although there are different views on the answer to this question, experts agree on this point: lemmings will not commit suicide collectively. When the number of lemmings increases sharply and local food becomes scarce, lemmings, like other animals, will spread to other places. It is observed that in the mountainous areas of Norway, the lemmings on the mountain spread to the valley, and some of them will gradually reach the lake and the seaside and settle down there. But with more and more latecomers, some will try to swim to the other side, and some will be drowned. This may be the source of the myth of collective suicide of lemmings. In recent years, some experts have tried to explain the mystery of the decline in the number of lemmings from their own changes. For example, with the increase of mouse population density, the social interaction and pressure between lemmings increase, which leads to the change of hormone levels in the body, thus reducing its fertility and becoming more aggressive. When the population density is too high, lemmings' reaction is not to sacrifice themselves, but to attack other lemmings and even kill each other. The myth that lemmings are about to die will not disappear as easily as the myth that lemmings fall from the sky. No matter how the experts clarify, this myth will always be passed down as a scientific fact and an educational natural wonder. After all, for many people, beautiful lies are better than cold facts. The life of the Arctic lemmings pays close attention to what is going on around them. Lemming is a very common and lovely little animal. It lives in the Arctic all the year round. It is oval, with short limbs, smaller than ordinary mice, with a maximum length of 15cm, short tail, small ears and timid eyes. But when cornered, it will also fly into a rage and fight back. Eskimos call them animals from the sky, while Scandinavian farmers directly call them "voles". This is because, in a certain year, their number will increase greatly, just like the sudden arrival of the heavenly soldiers. Although lemmings are mammals, they have strong reproductive ability. In the Arctic in March, when the rough courtship of the Arctic fox broke the quiet tundra, lemmings had already given birth to their first litter and were busy raising newborn children under the snow. In good years, a female lemming can give birth to 6-7 litters a year, and the newborn lemming can mate 30 days after birth (the highest record is that it can mate 14 days after birth). You can give birth to a litter of lemmings after 20 days of pregnancy, and each litter can give birth to 1 1. At this rate, a female mouse can give birth to thousands a year. In order to supplement the energy consumed in reproduction, lemmings eat an amazing amount, which is twice their own weight in one meal, and they have a wide range of diets. Almost all arctic plants such as grass roots, grass stems and mosses are included in their recipes, and they can eat 45 kilograms of food a year. Therefore, people call lemmings "fat and busy harvesters". There are many natural enemies of lemmings, such as owls, skuas, snow birds, arctic foxes, polar bears, etc. all feed on lemmings. A pair of snow birds and their children can eat 100 lemmings a day. Even herbivorous reindeer will kill lemmings, stomp them to death with their hooves, and then eat them, which can be regarded as improving their lives. People are most interested in the periodic fluctuation of lemmings and their natural enemies. Every 3-4 years, the number of lemmings will increase sharply, and usually it will start to decline after only one year. The investigation results show that in some years, a whole nest of lemmings can be found in the stomach of the Arctic fox, indicating that the Arctic fox dug lemmings out from under the snow. The increase in the number of lemmings provides excellent conditions for the reproduction of Arctic foxes. At this time, the arctic fox lives in the fox hole of 100% tundra, with an average of 8 nests. When the number of lemmings decreased, the food sources of Arctic foxes were seriously insufficient, and they had to feed on foods with low nutritional value. The female fox is physically weak and not pregnant. Even if she is pregnant, the young fox born is sickly and will die soon. In this way, the number of arctic foxes will decrease sharply 1 ~ 2 years. The same is true of lemmings, the staple food of snow birds. When the number of lemmings increases, the number of snow birds will also increase. When the number of lemmings decreased, a large number of snowbirds were forced to move south because of hunger. Therefore, in North America, a large number of snow birds can be seen every 3-4 years, which is rare between migrations. Turn into orange lemmings to attract natural enemies. In normal years, lemmings breed only in small quantities, so the number increases slightly or even remains the same. Only when the weather is favorable, the climate is suitable, and there is enough food, Qi Xin will multiply together in large numbers, so that its number will increase dramatically. Once it reaches a certain density, such as 1 hectare with hundreds of lemmings, a strange phenomenon will happen: at this time, almost all lemmings suddenly become restless, they run around, make noise, and stop eating. It seems that disaster is imminent and the end of the world is coming. At this time, they are uncharacteristically. They are no longer timid and run away from everyone. On the contrary, they are naturally fearless in the face of any natural enemy, and sometimes even take the initiative to attack. It's really a little fearless. What is even more incredible is that even their coat color has changed obviously, from gray-black to orange-red with obvious targets, so as to attract the attention of natural enemies and devour and consume them to a greater extent. At the same time, they also have a strong sense of migration, and they have gathered together to form a large group. First of all, they ran around as if they were in a hurry before leaving. Then, I don't know who gave the order, they will travel in a certain direction and go all the way at night, and the sea will always be their final destination. Interestingly, when they make such a large-scale death migration, they always leave a few similar caregivers to undertake the sacred task of carrying on the family line, so that they will not become extinct. All this seems to be well thought out and carefully arranged.