The class of mammals has long been a leader among all animals. Its representatives have the most progressive structural features of all organ systems, including the digestive one. Eating from birth is an essential condition for their existence and distribution.
Who are mammals?
The mammals class unites all representatives of the chordate type, which feed their young with milk. And it does not matter at all whether this representative will be a small field mouse or a giant African elephant. At birth, the source of mammalian energy is milk.
Eating from the first minutes after birth occurs in these animals with the help of specialized mammary glands. By their origin, they are modified sweat.
In primitive mammals, such as the platypus and echidna, they are very poorly developed and open outward with special pores. These animals have more in common with their ancestors - birds. First of all, it is the presence of cesspools - a specialized hole in which the reproductive, digestive and excretory systems secrete their products. At marsupials - kangaroos, koalas, wombats - ducts with milk open into the skin fold. It is in her that the cub spends the first time after birth, licking a valuable product directly from the skin. Since the placenta in such animals is poorly developed, they are born small, non-viable, blind, naked and not capable of independent existence.
Higher mammals are born completely different. They are quite well developed, many are able to move independently immediately after birth.
Such different heterotrophs
The energy source of mammals is a number of prepared organic substances, namely proteins, lipids and carbohydrates. Therefore, they, like all representatives of the animal world, are heterotrophs. In this they are fundamentally different from plants that can convert ultraviolet radiation into carbohydrates. But it is necessary and heterotrophs.
Scientists have long conducted a series of experiments that determine why animals need sunlight. It is he who is the signal for the beginning of molting, hibernation, seasonal migrations, the formation of sex hormones. With an increase in the duration of daylight hours, the process of the appearance of prolific offspring of mammals begins.
Predators
The source of mammalian energy is prepared food. But it enters the body in different ways. Thus, predatory animals attack and kill their prey on their own.
For this, there are a number of structural features: strong muscles, sharp claws and powerful teeth. One molar on each side of the jaw turns into a so-called predatory tooth. This is a modified molar tooth, which, thanks to its large size and sharp edge, can even violate the integrity of the victim's bones. Animal foods are rich in proteins and fats. Therefore, the energy received from its consumption is long enough.
The methods of obtaining food in this group of animals differ significantly. Some drive the victim until all of her powers are exhausted. Others attack prey suddenly. And also achieve success.
Predators differ in their mode of existence. For example, lions and wolves prefer to live and hunt in packs. Bears love loneliness.
Herbivores
But the source of energy for mammals is also ready-made food, which can be obtained not in such a "bloody" way. Very many representatives of the animal world prefer plant products. It is rich in valuable fiber - a natural carbohydrate. For example, rodents store seeds of cereal crops in reserve. And ruminants burp partially chewed grass and only then absorb the substances. There is only one difficulty. Such food is low-calorie. Herbivores have to eat it a lot and constantly be in search of food. In a temperate climate zone, its presence also depends on the season. And predators constantly strive to grab the poor herbivores. But for protection, they also have a number of features. First of all, these are strong hooves and horns. But most often these animals are helped by fast legs. Therefore, they prefer not to engage in an unequal battle with the enemy, but rather to hide.
Competition
As you know, environmental resources are quite limited. Therefore, mammals have to fight for food, habitat, shelters and sexual partners. As a result, competition arises between individuals of the same or different species. Naturally, the strongest wins in this fight. As a result, natural selection occurs, which is one of the driving forces of evolutionary transformations. Many argue with this theory. But studies by scientists have shown that animals living within the same range, over time, acquire significant differences in the color, structure of teeth and many organs.
Nutrition: proteins, fats, carbohydrates
Organic substances that enter the body of mammals along with food undergo a number of changes there. Fats as the source of energy are the most high-calorie substances. In the stomach, they break down to glycerol and fatty acids. In this case, twice as much energy is released than with a similar conversion of other organic substances.
Proteins are an important component of the diet of mammals. Being the basis of any animal organism, they perform a building, energy, storage and protective function. The constituent parts of proteins are amino acids. Scientists have proven that some of them are indispensable. This means that these substances cannot be synthesized in the body, but only enter it with animal food.
Carbohydrates begin to break down already in the oral cavity with the help of salivary gland enzymes. Different types of sugars are necessary for the metabolism of the body.
Drink, kids, milk!
The composition of milk in different species of mammals varies quite widely. But those babies who double their weight very quickly after birth eat a product, especially a rich protein. Such milk is produced by rabbits, deer, pigs, buffalo and sheep. The lactose carbohydrate necessary for the development and growth of a small organism is secreted by goats and cows. Rich in milk and minerals. This is a real storehouse of potassium, calcium, phosphorus, iron. And also a vitamin cocktail. Riboflavin, ascorbic acid, retinol, thiamine - this is not a complete list of valuable substances. Therefore, milk has long been considered not only tasty, but also a useful product, so necessary for the growing body of a small cub.