As among plants there is the most adapted dominant group - Angiosperms, so among animals there are organisms that are distinguished by a higher specialization in the structure of external and internal organs. These are mammals. In this article, we will consider the features of their structure, development, reproduction and classification.
Class Mammals: general characteristics
The characteristic of mammals includes the designation of all their features that they possess. Firstly, these are the most highly adapted animals that have managed to settle throughout the planet. They are found everywhere: in the equatorial bands, steppes, deserts and even in the waters of Antarctica.
Such a wide settlement on the planet is explained by the fact that the internal structure of mammals has its own advantages and features, which will be discussed later. Their appearance also did not remain unchanged. Many adaptive modifications undergo almost all parts of the body when it comes to any particularrepresentative.
In addition, the behavior of this class of animals is also the most highly organized and complex. This is also evidenced by the fact that Homo sapiens is considered one of the orders of mammals.
Higher brain development allowed people to rise above all other creatures. Today, mammals play a huge role in human life. They are for him:
- power supply;
- draft power;
- pets;
- source of laboratory material;
- farm workers.
Characterization of mammals is given according to numerous studies of different sciences. But the main one is called theriology ("terios" - the beast).
Classification of mammals
There are various options for grouping different species into groups. But the variety of representatives is too great to be able to dwell on any single option. Therefore, any classification can be supplemented, corrected and replaced by another.
Today, there are about 5, 5 thousand species of mammals, of which 380 species live in our country. All this diversity is combined into 27 units. Mammal groups are as follows:
- single pass;
- possums;
- tsenolesty;
- microbiota;
- marsupials;
- bandicoots;
- two-blade;
- jumpers;
- gold mole;
- aardvarks;
- hyraxes;
- proboscis;
- siren;
- anteaters;
- armadillos;
- lagomorphs;
- rodents;
- duppies;
- woolly wings;
- monkeys;
- insectivores;
- bats;
- equids;
- artiodactyls;
- Cetaceans;
- predatory;
- pangolins.
All this diversity of animals inhabits all environments of life, extends to all territories, regardless of climate. Also, extinct organisms are not included here, since together with them the number of mammals is about 20 thousand species.
External structure of mammals
As already mentioned, in addition to high organization inside, mammals also have clear distinctive features on the outside. There are several main such signs.
- The presence of a mandatory smooth or rough coat (in the case of a hairy person).
- Formations of the epidermis that perform a protective function - horns, hooves, claws, hair, eyelashes, eyebrows.
- Presence of skin glands: sebaceous and sweat glands.
- Seven vertebrae in the cervical spine.
- Oval-shaped testicles.
- Live birth as a way to reproduce offspring, and then take care of it.
- The presence of mammary glands to feed the young, which explains the name of the class.
- Constant body temperature or homoiothermia - warm-bloodedness.
- Aperture presence.
- Differentiated teeth of various structures and types.
Thus, the outer structuremammals clearly has its own characteristics. According to their totality, one can identify the place of an individual in the system of the organic world. However, as always, there are exceptions. For example, a rodent digger does not have a constant body temperature and is cold-blooded. And platypuses are incapable of live birth, although they are the first animals.
The skeleton and its features
The structure of the skeleton of mammals can rightfully be considered their distinctive feature. After all, only they have it clearly divided into five main departments:
- skull;
- chest;
- spine;
- lower and upper limb belt;
- limbs.
At the same time, the spinal column also has its own characteristics. Includes:
- cervical;
- chest;
- lumbar;
- sacral departments.
The skull is much larger in size than that of all other representatives of the animal world. This indicates a higher organization of brain activity, mind, behavior and emotions. The lower jaw is movably attached to the skull, in addition, there is one zygomatic bone in the structure of the face.
The structure of the skeleton of mammals is especially the fact that the spine consists of placetal (that is, flat) vertebrae. No other representative of the fauna has such a phenomenon. In addition, the spinal cord is located inside the column with a straight cord, and its gray matter has the shape of a "butterfly".
The limbs, or rather, their skeleton, are not the same in terms of the number of fingers, the length of the bone and other parameters. This is due to the adaptationto a certain way of life. Therefore, such details of the skeleton should be studied for each specific representative.
Structure and functions of the systems of the internal organs of a mammal
What is located inside the animal organism and constitutes its essence is the most important part of the entire individual. It is the internal structure of mammals that allows them to occupy a dominant position on land and at sea. All these features lie in the structure and functioning of each organ, and then, in the whole organism.
In general, there is nothing exceptional in their structure. The general principles remain. It's just that some organs have reached their maximum development, which left a general imprint on the perfection of the class.
The most voluminous topic to study is the structure of mammals. A table would therefore be the best option to reflect the general systemic organization of the internal structure of animals of this class. It can reflect the composition of organs, the main systems and the functions they perform.
| Organ system | Organs, its constituents | Performed functions |
| Digestive | Oral cavity with tongue and teeth, esophagus, stomach, intestines and digestive glands | Capture and grind food, push into the internal environment and completely digested into simple molecules |
| Respiratory | Trachea, larynx, bronchi, lungs, cavitynose | Gas exchange with the environment, oxygenation of all organs and tissues |
| Circulatory | Heart, blood vessels, arteries, aorta, capillaries and veins | Implementation of blood circulation |
| Nervous | Spinal cord, brain and nerves extending from them, nerve cells | Provision of innervation, irritability, response to all influences |
| Musculoskeletal | A skeleton made up of bones and the muscles attached to them | Providing a constant body shape, movement, support |
| Excretory | Kidneys, ureters, bladder | Removal of liquid metabolic products |
| Endocrine | Glands of external, internal and mixed secretion | Regulation of the work of the whole organism and many internal processes (growth, development, formation of fluids) |
| Reproductive system | Includes external and internal genital organs involved in fertilization and fetal formation | Reproduction |
| Sense Organs | Analyzers: visual, auditory, gustatory, olfactory, tactile, vestibular | Providing orientation in space, adaptation to the surrounding world |
Circulatory system
Features of the structure of mammals are the presence of a four-chambered heart. This is due to the formation of a complete partition. It is this fact that is at the head of the fact that these animals are warm-blooded, haveconstant body temperature and homeostasis of the internal environment of the body as a whole.
Nervous system
The brain and spinal cord, their structure and functioning are structural features of mammals. After all, no animal can experience as many emotions as they do. Nature endowed them with the ability to think, remember, think, make decisions, quickly and correctly respond to dangers.
If we talk about a person, then it is generally difficult to convey the entire scope of the superiority of the mind. Animals have instincts, intuitions that help them live. All this is controlled by the brain, together with other systems.
Digestive system
The internal structure of mammals allows them not only to adapt to living conditions, but also to choose their own food. So, ruminants have a special structure of the stomach, which allows them to process grass almost continuously.
The structure of the dental apparatus also varies greatly depending on the type of food. In herbivores, incisors predominate, while in carnivores, fangs are clearly expressed. All these are features of the digestive system. In addition, each species produces its own set of digestive enzymes for ease and efficiency in the absorption of food.
Excretory Organ System
The internal organs of mammals, which take part in the excretion of liquid metabolic products, are arranged according to the same principle. kidneysprocess a huge volume of liquid and form a filtrate - urine. It is excreted through the ureters into the bladder, which, when filled, is emptied into the environment.
Endocrine system
All the internal structure of mammals is uniform and consistent in their work. However, there are two systems that are coordinators and regulators for all others. This is:
- nervous;
- endocrine.
If the first one does this through nerve impulses and irritations, then the second one uses hormones. These chemical compounds have tremendous power. Almost all processes of growth, development, maturation, development of emotions, secretion of gland products, metabolic mechanisms are the result of the work of this particular system. It includes important organs such as:
- adrenals;
- thyroid gland;
- thymus;
- pituitary gland;
- hypothalamus and others.
Sense Organs
Reproduction and development of mammals, their orientation in the outside world, adaptive reactions - all this would be impossible without the senses. Which analyzers make up them, we have already indicated in the table. I just want to emphasize the importance and high level of development of each of them.
The organs of vision are very well developed, although not as sharp as in birds. Hearing is a very important analyzer. For predators and their prey, this is the basis and guarantee of a successful life. The lion's roar can be heard by the victim, being several kilometers away.
The vestibular apparatus helps to quickly change the position of the body, move and feel comfortable at any turn of the body. The sense of smell also serves as the key to a well-fed day. After all, most predators smell their prey.
Reproduction and developmental features of mammals
Reproduction and development of mammals occurs according to all generally accepted principles. Females and males have copulatory organs for mating and the fertilization process. After that, the female bears the cub and reproduces it into the world. However, further on, the difference between mammals and all other, lower organized individuals begins. They take care of their offspring, introducing them to adult and independent life.
The number of cubs is not so large, so each of them receives care, affection and love from their parents. Man, as the pinnacle of development in the animal kingdom, also demonstrates a high degree of maternal instinct.
