Recently, the ninth child of a young Malian mother in Africa has attracted everyone's attention, but this is not the most child-produced, and the record for the most surviving multiple births in history belongs to a Brazilian mother, who gave birth to decuplets in 1964, all of which survived healthily.
But in the entire animal kingdom, human fertility is still not enough to see, not counting the two relentless reproductive machines of insects and fish. Even among mammals, there are many species that come ahead of humans.
So which kind of mammals are the most prolific? Is it a rabbit? Is it a rat? Or something else?
In short, honor belongs to rodents, and what we are going to introduce today is a cute little animal with the highest fertility: lemming.
Lemming belongs to the mammalian, rodent, and hamster families, and there are four genera below: ring-necked lemmings, lemmings, forest lemmings, and swamp lemmings.
They all live in tundra regions to the north near the North Pole, feeding on a variety of grasses, lichens, young leaves, and plant roots. They eat a lot of food, and they can eat food equivalent to twice their own weight in one meal. Although they are not large, with adult weights between 25-35 grams and no more than 20 centimeters in length, they are too numerous.
Lemmings usually live no more than one year. Male lemmings have a territorial area of about 2,000 square meters, and female lemmings have a smaller territorial area, but there are also about 300 square meters.
A pair of lemmings can breed seven or eight times a year, each time can give birth to 12-20 lemming mice, and these lemmings can be sexually mature in about 20 days and have the ability to be parents. In this way, how many lemmings and their offspring can breed in a year? Let's take a look.
If a pair of lemmings starts in March to consider having children, we calculate according to the lower limit of 12 per litter, the second generation of lemmings is a total of 84, if the proportion of men and women is appropriate, twelve is exactly 6 pairs. After 20 days, the first 6 pairs of the second generation began to give birth, 12 per litter, 72 at once, a total of 6 litters, then 432. After 40 days, the 6 pairs of the third litter are also fertile, and they can give birth to a total of 5 litters, or 360 if there are 12 litters per litter. There can be a total of 2160 lemmings of the third generation. After 40 days, the first 36 pairs of the third generation also began to breed, and their first litter could give birth to 432, a total of 5 litters, 2160. There are also second to seventh births of the third generation, so the total number of lemmings of the fourth generation is 15,120. According to this calculation, the fifth generation is 90720, the sixth generation is 326592, the seventh generation is 653184, and the eighth generation, the last batch of the year, is 559872. From two in March, to the end of August and the beginning of September, it will become a huge team of 1647086.
So lemmings are one of the cornerstones of the Arctic ecosystem, and basically all predators feed on it, including arctic foxes, snowy owls, skuas, and polar bears. Even vegetarian reindeer trample them to death and eat them when they encounter migrating lemmings.
The Arctic region is very large, so lemmings with such amazing reproductive ability will not cause overcrowding, at most 250 lemmings per hectare, and their food intake is still affordable.
But the number of lemmings is drastically reduced every three to four years, and this is the famous legend of lemming suicide.
Disney has a fake documentary called White Wilderness, which tells the story of lemmings, but they were filmed in Canada, and the density of lemmings here is not large at all, so the lemmings here have no habit of moving on a large scale. After waiting for two days, impatient staff drove the lemming off a cliff and faked the suicide scene.
When lemmings migrate in large numbers, their coat color will turn bright orange-red, as if greeting predators and coming to eat me.
There is no consistent explanation for this phenomenon, and the following statements sound more reasonable.
One: Survival pressure due to increased lemming populations.
But as mentioned earlier, the maximum density of lemmings does not exceed 250 per hectare, and there is no shortage of food.
Second: Lemmings themselves have social fear problems, and too much density will cause them to behave abnormally.
It is possible that according to the maximum density, the living area of each lemming is only 40 square meters, and it is understandable that it is not adapted.
Three: climatic reasons.
Climate causes are more likely, and the cycle of El Niño and lemming mass deaths is largely consistent.
Summary: Lemmings are cute little animals that have a vibrant and mysterious lifestyle.
The unsolved mysteries of them are worth exploring and studying.
Thank you for watching.
Eurasian tundra lemmings past and present cycles fluctuate
Author: Danell, K; Yushan Wang Title: Journal of Human Environment
Morphological variation of lemmus in the Arctic region of Eurasia
Author: Abram.,N; Zhou Lizhi Title: Journal of human environment
A study of the relationship between lemming and vole population outbreaks and El Niño-Southern Oscillation in Europe
Author: Zhang Zhibin Title: Science Bulletin