Animal Kingdom

The Role of Animals in Nature and Human Life

Unlike plants, animals are heterotrophic organisms that feed on ready-made organic compounds. Fungi, which are also heterotrophs, differ from animals in
that they absorb organic substances over the entire surface of their bodies, while animals use cavity digestion.

Unlike plant growth, the growth of most animals is limited and occurs, as a rule, only during certain periods of development. Only some of them (such as
certain crayfish, crocodiles, and turtles) grow throughout their lives.

Animal cells, unlike plant cells, do not have a cell wall, plastids, or vacuoles. The reserve carbohydrate in animal cells is not starch, but glycogen. The end
products of nitrogen metabolism in animals are ammonia, urea, and uric acid.

In the system of living nature, animals are consumers (from "consumo" - to consume, "consumenti" - consumers). Animals depend on plants (producers),
which produce organic matter for them. In the animal kingdom, about 2 million species have been described, adapted to life on the surface of the land, soil,
fresh and sea water, and in the air environment.

In everyday life, two concepts are often confused: animals and mammals. In science, the term "animals" has a broader meaning. In addition to mammals,
animals include many other organisms: fish, birds, insects, arachnids, mollusks, starfish, all kinds of worms, and more.

Similarities and Differences with Other Kingdoms

Animals are in many ways similar to representatives of other kingdoms. For example, animals and plants have a cellular structure, a similar chemical
composition, and many common properties (metabolism, heredity, variability, irritability). This is how global connections are manifested, reflecting the
commonality of all living things on Earth.

The Role of Animals in Ecosystems

As consumers of ready-made organic matter, animals constitute the most important links in food chains and networks. As a result of vital processes and due
to their mobility, animals consume and redistribute a huge amount of matter and energy in the biosphere, thereby accelerating the biological cycle of substances.

The role of animals (especially insects) as pollinators of flowering plants and spreaders of seeds and fruits is significant. Their contribution to soil-forming
processes (worms, insect larvae, burrowing rodents) and to the formation of landscapes (burrowing animals, ungulates, beavers) is undeniable.

The animal world is part of the system of living nature and has a great impact on the life of the biosphere and humans.

The Importance of Animals in Human Life

The importance of animals in human life is primarily associated with the use of many species as food sources and suppliers of various forms of raw materials.
Animal food enriches the human diet with high-calorie, easily digestible complete proteins. Its suppliers are various types of crustaceans, mollusks, fish, hunting
and industrial animals, and those bred by humans. Fur and pelts are supplied by many types of animals: sable, marten, squirrel, beaver, arctic fox, sea otter.
Natural silk is obtained by humans as a result of breeding silkworms. Suppliers of valuable medicinal raw materials include bees and snakes. The glands of
some animals are used in the production of hormonal drugs. Many animals are indispensable for humans as a means of transportation and in physical work
(horse, camel, deer, buffalo, elephant). Some representatives of the animal world are used as laboratory objects in educational and experimental work and are
 traditional objects of scientific research (amoeba, ciliates, beetles, insects, frogs, pigeons, rats, mice, guinea pigs, cats, dogs, etc.).

Negative Impact of Animals on Humans

Some species of animals have a significant negative impact on humans. Many species of insect pests, ticks, and rodents cause great harm to agricultural crops
during periods of mass reproduction, reducing their productivity and quality. A number of animals are pathogens (parasitic protozoa, worms, arthropods) and
carriers of pathogens of humans and animals (flies, dog ticks, etc.). The poison of some animals is dangerous for humans.

Ecological Value of Animals

The value of animals for humans lies not only in the useful products they provide but also in their role in the biogenic cycle of substances. Animals clean the
 environment from organic pollution, utilize organic residues, and are necessary links in food chains in biogeocenoses.

Animals are heterotrophic organisms that feed on ready-made organic compounds. The animal world is part of the system of living nature and has a great
impact on the life of the biosphere and humans.