Mammals

Mammals (Mammalia), or animals,class the most highly organized animals subtype of vertebrates (Vertebrata). The advanced features of the organization of mammals: a highly developed nervous system, causing complex behaviours; a live birth and feeding kids milk; perfect thermoregulation, which provides stability of body temperature. For most M typical hair, skin, breast, division of thoracic and abdominal cavities partition (iris), differentiated dentition (incisors, canines and molars) with two shifts of teeth (milk and permanent), the left arch of the aorta, bezyadernoy red blood cells and some other signs. Like animals, who have mastered all habitats on earth and adapted to different modes of transportation, mammals have diverse characteristics of the organisation and external appearance. Among M. the most common terrestrial form, but there is also an underground (mole), water (whale), wood (protein), flying (bats). Highly variable, and size M - from small shrew (belasovka-baby) weight 2 g and a length of 4,5 cm to whale, whale length of over 30 m and weight up to 150 T.
The mammal class is divided into 3 sub-classes - pervozveri (with one group - the one-pass), lower animals (with one squad - marsupial) and higher animals, or placental presented 17 modern units, numbering about 3.5 thousand species. In the fauna of the USSR common representatives of 9 units M: insectivores, bats, rodents (see), lagomorphs, predators, pinnipeds, cetaceans, and odd-toed ungulates, consisting of about 300 species.
The value of M for a man is very great. Some Meters of domesticated (see Pets). Among wild mammals there are a large number of species, widely used by man to obtain furs, leather, meat, and others (see food animals). Widely used M. and for the needs of medicine. Many types of M - essential laboratory animals (see): white mice, rats, Guinea pigs, hamsters, rabbits, cats (see), dogs (see), monkeys (see) and other Some Meters are used for treatment and preventive sera (for example, horses). From the endocrine glands M. receive medical hood, hormones. A number of products derived from Meters, has a subsidiary role in pharmacology (fat, fat, spermaceti and others).
Along with the benefit of mammals can bring significant harm. Large predators destroy home and useful wild animals and birds. Many mammals - forest pests and crops cultivated plants, food stocks in warehouses and housing rights. As a source of infection by pathogens dangerous to human diseases known many representatives Meters Rodents can spread the plague, tularemia, leptospirosis, cutaneous leishmaniasis, some ricketsiosis; bats - rabies; lagomorphs - tularemia, Crimean hemorrhagic fever; predators rabies, trichinosis, and other helminth infections; artiodactyls, especially C. agricultural, animal brucellosis, anthrax, leptospirosis, SAP, foot and mouth disease, toxoplasmosis trichinosis, and other; insectivorous - tularemia. Many types of M - mass proximately various parasites - fleas, ticks and gamasid mites.