Why are rats called rats when they are so small?

Rats, also known as rats. But more colloquially known as "rats". Why is there an "old" man in front? According to the "Compendium of Materia Medica", "it has the longest lifespan, so it is called a mouse." ”

But don't rats live long? Let's compare, see that elephants can live for an average of 60-70 years, and some individuals can live up to 150 years; Rhinoceros camels can live up to 40-50 years; Squirrels can live up to 10-12 years; Hares can live for 7-8 years. The average age of rats is only 2 to 2 and a half years old, and they are very old when they live to 3 years old, and some can live to 4 to 5 years old, but this is already an "old birthday star".

From this, it seems that rats do not live long.

So why is there a saying that "rats live the longest"? According to research, this may be due to its strong fecundity. Generally speaking, young mice can reach sexual maturity in two or three months, its reproductive function can be maintained for one to two years, mice can generally give birth to five or six litters in a year, in good living conditions, it can mate and reproduce all year round, if you do not count the dead individuals, the number of their offspring can reach more than 35,000.

The offspring of rats grow quickly, so people mistakenly believe that rats have a long lifespan.

As for the kitten, it may be what people call it.

The name is just a cat, a one-word noun, the old one is called an old cat, and the small one is called a kitten.

The old one is called the old mouse, and the small one is called the little mouse.

The mouse is petite, the body is tapered, the body color is generally gray or brown, the upper and lower jaws each have a pair of well-developed incisors, the mouth is small, the finches are distributed on both sides, the eyes are round, and the color is black and bright.

The body shape of the mouse is cone-shaped, and the teeth of the mouse are very distinctive. The front teeth of rats are very well developed, and when rats do bad things, their front teeth often become a very important tool. The tail of the mouse is very long, and the eyes and mouth of the mouse are small, and the ears are also very small.

Many people are very disgusted when it comes to rats, because the external form and various parts of the life habits of rats are very annoying. Many people are also scared when they see mice, which are often gray or dark in color, which is really ugly.

Mus mus (small mouse): gray coat, small individuals, in addition to the root of the wall to make a nest, often with people as a companion, weight rise Qi about 20-30g.

In rural areas, the basic housing facilities such as adobe houses, doors and windows are very simple. It's a piece of cake for a rat to get into the house and steal food. And it's well hidden, just drill a hole in the ground.

In this environment, rats have plenty of room to move, have enough food, and are naturally very large. But the countryside is basically small buildings made of reinforced concrete, and the doors and windows are also impeccable. It is impossible for rats to come and go freely.

Can only run roughly. All prices are **, but there is no food**, and it is difficult for farmers to farm to make money, so they go to the city to work one after another, and many farmlands are abandoned. The land is also sold to grain dealers as soon as it is harvested, and instead of hoarding grain at home, the rats live on food, and now that the grain has decreased, their food has also decreased, and they cannot eat enough, so the number naturally decreases.

The natural predator of rats is cats at home and weasels outside. Recently, the number of cats and weasels in the house has been increasing, and the natural predators of rats are increasing, and the living space of rats is getting smaller and smaller, and their numbers are getting smaller and smaller. I know that the environment has changed and still is.

I know that survival of the fittest is particularly well suited to the previous environment of large rat survival. That is, the big rats are gradually being replaced by the small mice. After the small body of the mouse has reduced food, they can also eat some food to reproduce.

There are more than 1,700 species of rats in the world, about 170 species in China and 33 species in the south, the most common being large rats and small mice. The teeth of the big rat are still very strong, he can make holes in the ground, and he can even bite trees. In the past, in rural areas, the living environment was simple, and most of them were mud houses, so rats could get food indoors or drill a simple hole to enter.

At that time, it was not me, but in the countryside began to build small buildings of reinforced concrete, with doors and windows installed firmly. At this time, the rat wants to enter through the wall, and the possibility is not very large, so he can only find another way.

There are fewer and fewer seeds for food. In recent years, the food ** is very low, many farmers have stopped farming, basically go to the city to work, overgrown with weeds in winter, such a big mouse can not find a lot of food, and will naturally go to other places to wander. The third reason is human intervention.

In the past, people had very few methods for rats, but now there are many methods and tools to eliminate mice, which overwhelm the living space of rats to a certain extent.

Because now rats have no food to steal, with the development of science and technology, in fact, houses have been built in rural areas, and rats have no holes to drill

Because most of the cities are very clean now, and everyone's home is also very clean, these rats can't find food, so naturally they don't grow big.

Shrew (qú jīng) (scientific name: sorex araneus linnaeus), belonging to the insectivorous order Shrew, lives by eating earthworms, insects, etc., although it looks very much like a mouse, but in fact the two have nothing to do with each other.

It is the first placenta, produced in the Cretaceous period of the Mesozoic Era, and is the smallest mammal in the world (body length only 4 6 cm, tail length 4 5 cm, weight 2 5 g). The eyes are small, the vision is poor, the sense of hearing and smell is developed, and the outer ear shell is not obvious. It is suitable for eating insects and is a small and cute beneficial animal.

The shrew's feet have five clawed toes, a long pointed snout, small eyes, short ears, thin limbs, small claws, and a tail that is longer than half its body length.