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 consider the features of their structure, development, reproduction and classification.
Mammals class: general characteristic
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 spread throughout the planet. They are found everywhere: in equatorial stripes, 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 considered later. Their appearance also did not remain unchanged. Virtually all parts of the body undergo many adaptive modifications when it comes to any particular representative.
In addition, the behavior of this class of animals is also the most highly organized and complex. This is evidenced by the fact that one of the orders of mammals is considered Homo sapiens.
Higher brain development has allowed humans to rise above all other creatures. Today, mammals play a huge role in human life. They are for him:
- power source;
- draft power;
- pets;
- source of laboratory material;
- agricultural workers.
Characterization of mammals is given according to numerous studies of various sciences. But the main one is called theriology ("therios" - the beast).
Mammal classification
There are various options for combining different species into groups. But the diversity 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 squads. The mammalian groups are as follows:
- single pass;
- possums;
- price congestion;
- microbioteria;
- marsupials;
- bandicoots;
- bivalve;
- jumpers;
- gold moles;
- aardvarks;
- damans;
- proboscis;
- sirens;
- anteaters;
- armadillos;
- hare-like;
- rodents;
- dull;
- wool wings;
- monkey;
- insectivores;
- bats;
- artiodactyls;
- artiodactyls;
- cetaceans;
- predatory;
- pangolins.
All this diversity of animals inhabits all living environments, spreads in all territories, regardless of climate. Also extinct organisms are not included here, since with them the number of mammals is about 20 thousand species.
The external structure of mammals
As already mentioned, in addition to the high organization inside, mammals have obvious distinctive features outside. Such signs can be identified several main.
- The presence of a mandatory smooth or rough coat (in the case of human hair).
- Formations of the epidermis that perform a protective function - horns, hooves, claws, hair, eyelashes, eyebrows.
- The presence of skin glands: sebaceous and sweat.
- Seven vertebrae in the cervical spine.
- Seed plants in the form of an oval.
- Live birth as a way of reproducing offspring, and then caring for it.
- The presence of mammary glands for feeding cubs, which explains the name of the class.
- Constant body temperature or homoyothermy - warm-bloodedness.
- The presence of a diaphragm.
- Differentiated teeth of various structures and types.
Thus, the external structure of mammals clearly has its own characteristics. By 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 belongs to the cold-blooded. And the platypus is incapable of live birth, although they are the first animals.
Skeleton and its features
The structure of the skeleton of mammals can rightfully be considered their distinguishing feature. After all, only they have it clearly divided into five main departments:
- skull;
- rib cage;
- spine;
- belt of lower and upper extremities;
- limbs.
In this case, the spinal column also has its own characteristics. It includes:
- cervical;
- thoracic;
- lumbar;
- sacral departments.
The skull is much larger in size than all other representatives of the animal world. This indicates a higher organization of brain activity, mind, behavior and emotions. The lower jaw is attached to the skull movably, in addition, in the structure of the face there is one zygomatic bone.
The structure of the skeleton of mammals is especially due to the fact that the spine consists of placental (i.e. flat) vertebrae. No other representative of the fauna has such a phenomenon. In addition, the spinal cord is located inside the column with a direct cord, and its gray matter has the shape of a “butterfly”.
The limbs, or rather, their skeleton, are not the same in the number of fingers, bone length, and other parameters. This is due to adaptation to a certain lifestyle. Therefore, such details of the skeleton should be studied for each specific representative.
The structure and functions of the systems of the internal organs of a mammal
That which is located inside the animal organism and constitutes its essence is the most important part of the whole individual. It is the internal structure of mammals that allows them to occupy a dominant position on land and at sea. All these features are in the structure and functioning of each organ, and then, and the whole organism.
In general, nothing exceptional is observed in their structure. General principles are retained. Just some organs have reached their maximum development, which left a general imprint on the perfection of the class.
The largest topic to study is the structure of mammals. The table therefore will 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.
The structure and functions of the systems of the internal organs of a mammal| Organ system | The organs that make up it | Functions Performed |
| Digestive | Oral cavity with tongue and teeth, esophagus, stomach, intestines and digestive glands | Capturing and grinding food, pushing into the internal environment and complete digestion to simple molecules |
| Breathing | Trachea, larynx, bronchi, lungs, nasal cavity | Gas exchange with the environment, oxygen saturation of all organs and tissues |
| Circulatory | Heart, blood vessels, arteries, aorta, capillaries and veins | Blood circulation |
| Nervous | Spinal cord, brain and nerves emanating from them, nerve cells | Providing innervation, irritability, response to all influences |
| Musculoskeletal | A skeleton made up of bones and the muscles that attach to them | Ensuring a constant body shape, movement, support |
| Excretory | Kidneys, ureters, bladder | Excretion 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 | Breeding |
| Sensory organs | Analyzers: visual, auditory, gustatory, olfactory, tactile, vestibular | Providing orientation in space, adaptation to the outside world |
Circulatory system
The structural features of mammals are the presence of a four-chamber heart. This is due to the formation of a complete septum. This fact is at the head of the fact that these animals are warm-blooded, have a constant 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 is capable of experiencing as many emotions as they are. Nature endowed them with the ability to think, remember, think, make decisions, quickly and correctly respond to dangers.
If we talk about man, then it’s generally difficult to convey the entire scope of the superiority of reason. Animals have instincts, intuition, which help them live. All this is controlled precisely 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 nutrition. Incisors predominate in herbivores, and fangs are pronounced in predators. All these are the features of the digestive system. In addition, each species produces its own set of digestive enzymes for ease and effectiveness in the absorption of food.
Excretory system
The internal organs of mammals, which are involved in the excretion of liquid metabolic products, are arranged on the same principle. The kidneys process a huge amount of fluid and form a filtrate - urine. It is secreted by the ureters into the bladder, which, when filled, is emptied into the environment.
Endocrine system
The entire internal structure of mammals is one and consistent in their work. However, there are two systems that are the coordinators and regulators for everyone else. It:
If the first does this through nerve impulses and irritations, the second uses hormones. These chemical compounds have tremendous power. Almost all processes of growth, development, maturation, development of emotions, the allocation of gland products, metabolic mechanisms - this is the result of the work of this particular system. It includes such important organs as:
- adrenal glands;
- thyroid;
- thymus;
- pituitary;
- hypothalamus and others.
Sensory organs
The reproduction and development of mammals, their orientation in the surrounding world, adaptive reactions - all this would be impossible without sense organs. What analyzers they make up, 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 sharply as in birds. Hearing is a very important analyzer. For predators and their victims, this is the basis and guarantee of a successful life. The victim can hear the lion's roar, being several kilometers away from him.
The vestibular apparatus helps to quickly change the position of the body, move and feel comfortable at any turns of the body. Smelling also serves as a guarantee of a well-fed day. After all, most predators smell their victims.
Reproduction and developmental features of mammals
The reproduction and development of mammals occurs according to all generally accepted principles. Females and males have copulative organs for mating and the fertilization process. After that, the female carries the calf and reproduces it in the light. However, further, the difference between mammals and all other, lower-organized individuals begins. They take care of their offspring, introducing them into 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 world, also demonstrates a high degree of maternal instinct.