What are the main characteristics of mammals, what are the main characteristics of mammals

1. Mammals.

Physical characteristics are:

First, their ** is generally thicker than other vertebrates, and it is composed of epidermis and dermis; Clause.

2. Mammals have regenerated teeth in their mouths; Clause.

3. Mammals are viviparous, except for the order Monofora. Clause.

4. Mammals have a highly developed nervous system, the brain is much more developed than other vertebrates, and there are 12 pairs of cranial nerves. In addition, the lactating heart is divided into two atrial appendages and two ventricles; There are red blood cells.

But there is no nucleus.

2. The characteristics of social behavior are: a certain organization is often formed within the group; There is a clear division of labour among members; There is also a strict hierarchy For example, in the group life of baboons, the "leader" is the male baboon, and the other members are obedient to him.

Mammals are the most widespread group of species in the animal kingdom. As a type of homeothermic animal, they can maintain their mobility in colder environments, and organs such as sweat glands can help them control their body temperature in hot environments, so they can adapt to a variety of living environments with different temperatures and terrains. The main characteristics of mammals are viviparity and lactation.

Viviparity and lactation ensure a high survival rate of offspring. Viviparous lactation, with the exception of the most primitive monopore oviparous, is viviparous. The higher species form the tissue of mother-child nutrient exchange (i.e., the placenta) between the embryo and the uterine wall.

The mother animal breastfeeds and raises the baby for a longer time, so that the offspring has a higher survival rate, and the baby animal can also learn to acquire adaptation skills.

2 Evolutionary History.

The earliest mammal fossil is the Wu megacranial beast found in China, which lived 200 million years ago in the Jurassic period. Fossilly, a very important difference between mammals (especially early mammals) and reptiles is their teeth. Each tooth of a reptile is the same and does not differ from each other, whereas the teeth of mammals differentiate into different morphologies according to their different positions on the jaw.

In addition, reptiles' teeth are constantly renewed, and mammalian teeth are no longer renewed except for baby teeth. In the animal kingdom, only mammals have three bones in their ears. They evolved from the two jaws of reptiles.

All mammals in the Mesozoic era were small. After the extinction of the dinosaurs, mammals occupied many ecological niches. By the Quaternary period, mammals had become the dominant animals on land.

Like birds, mammals evolved from reptiles.

Mammals have hairs on the surface of their bodies, generally divided into five parts: head, neck, trunk, limbs and tail; breathe with your lungs; has a constant body temperature and is a homeothermic animal; The brain is large and well developed; Suckle; Viviparous. Mammalism and viviparity are the most distinctive features of mammals. The embryo develops in the mother's body, and the mother animal directly produces the fetus, and the mother animal has mammary glands that can secrete milk to feed the fetus.

Mammalian teeth are divided into incisors, canines, etc.

Mammals are homeothermic, vertebrates, mostly viviparous, and feed their offspring through their mammary glands. Mammals are the most advanced stage in the history of animal development, and they are also the most closely related to human beings. Mammals have many unique traits that have led to great evolutionary success.

Mammals are a class under the subphylum Vertebrates, and their scientific name is Mammalia. Mammals are characterized by having mammary glands (both male and female), in which the mammary glands of female mammals are highly developed.

Mammals are of great variety and have a wide range of divisions, mainly according to shape, skull, teeth, appendages, and reproductive patterns.

Common mammals are: tigers, wolves, rats, deer, martens, monkeys, tapirs, sloths, zebras, dogs, foxes, bears, elephants, leopards, musk oxen, lions, antelopes, rhinoceros, etc.

All mammals are homeotherms, and the fur on their body can help maintain their body temperature.

The main characteristics are: the surface of the body is hairy, and it is divided into five parts: head, neck, torso, limbs and tail like a sock; breathe with your lungs; has a constant body temperature and is a homeothermic animal; The brain is large and well developed; Suckle; Viviparous. Mammalism and viviparity are the most distinctive features of mammals.

Mammals are the animals with the highest morphological structure and the most complete physiology in the animal world. Compared to other animals, the most prominent feature of mammals is that they are viviparous and their young are fed with milk secreted by the mother's Wanghu. Mammals have a well-developed brain, so they can produce more complex behaviors than other animals, and can constantly change their behavior to adapt to changes in the external environment.

There are more than 4,000 species of mammals in the world, and although they are all highly evolved, they still have a lot in common: almost all mammals are warm-blooded, with a basically constant body temperature, and their bodies are covered with hair to protect their bodies, isolate them from heat and cold, and so on.