Over the entire history of human existence, a lot of knowledge has accumulated about the diversity of living nature. With the help of the science of taxonomy, all living nature is divided into kingdoms. In this article we will tell you which kingdoms of living organisms biology studies, about their features and characteristics.

The difference between living nature and inanimate nature

Distinctive features of living nature are:

• growth and development;
• breath;
• nutrition;
• reproduction;
• perception and response to environmental influences.

However, distinguishing living organisms from inanimate nature is not so easy. The fact is that many objects are similar in their chemical composition. For example, salt crystals can grow. And, for example, the seeds of plants that belong to living nature remain dormant for a long time.

All living organisms are divided into two types: non-cellular (viruses) and cellular which are made up of cells.

Unlike all existing living organisms, viruses do not have cells. They settle inside the cell, thereby causing various diseases.

Also a characteristic feature of all living things is the similarity of internal chemical compounds. An important factor is the metabolism with the environment, as well as the response to influences from the external environment.

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All living nature has its own classification. Kingdoms, types, classes of living organisms are the basis of biological systematics. Cellular organisms consist of two superkingdoms: prokaryotes and eukaryotes. Each of them is divided into separate kingdoms, levels of the hierarchy of the scientific classification of all existing biological species. Scientists group bacteria, plants, fungi and animals into separate kingdoms.

Rice. 1. Kingdoms of living organisms.

The human body belongs to the animal kingdom.

Bacteria

These organisms are classified as prokaryotes because they do not have a nuclear membrane. There are no organelles inside the cell; DNA is located directly in the cytoplasm. They live everywhere, they can be found in the depths of the earth's surface and on mountain peaks.

Another type of prokaryotes are archaea, which live in extreme conditions. They can be found in hot springs, the waters of the Dead Sea, animal intestines, and soil.

Mushrooms

This group of wildlife is quite diverse. They are divided into:

• cap mushrooms (outside they have a leg and a cap, which are attached to the surface of the soil using mycelium);
• yeast ;
• mukor - a single-celled fungus of microscopic size. If it is present, a fluffy grayish coating is formed, which turns black over time.

Plants

Inside a plant cell there are organelles, such as chloroplasts, that are capable of carrying out the process of photosynthesis. Plant cells are surrounded by a strong wall, the basis of which is cellulose. Inside the cell there is a nucleus, cytoplasm with organelles.

Rice. 2. The structure of a plant cell.

Animals

An animal cell does not have a strong wall, like a plant cell, so some of them are able to contract, for example, the cells of the muscular system. Animals move actively and have a musculoskeletal system. Inside the animal's body there are entire systems of organs that regulate the functioning of the entire organism.

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Taking into account fossil and modern organisms, the system of the organic world includes from 4 to 26 kingdoms, from 33 to 132 types and from 100 to 200 classes (I.A. Mikhailova, O.B. Bondarenko, 1999).

By the middle of the 20th century. About 2 million species of living organisms have been described (their total number is estimated at several million). It is assumed that from the beginning of the Cambrian, i.e. In about 600 million years, about 99.9% of the species that lived on Earth became extinct. Consequently, their total number, taking into account paleontological species, is about 2 billion.

Species diversity (the number of species in a taxon) is related to the size of organisms (see Fig. 27). In animals, the largest number of species are those whose body length is in the range of 1 - 10 mm. Animals with a body length of at least 10 mm are characterized by a pronounced tendency to decrease species diversity with increasing size. In particular, a threefold increase in body length corresponds to a decrease in the number of species by approximately 10 times (R. May, 1981).

The taxonomy uses the following categories: first - Kingdom (Regnum) as the highest taxonomic category recognized by the currently valid International Codes of Botanical and Zoological Nomenclature. However

Rice. 27.

(according to: R. May, 1981) recently it has been recognized as advisable to distinguish taxa of a higher rank - super-kingdoms or domains (Super-regnum), which are united by an empire - “Life”. According to the results of molecular biological studies, the empire is divided into three domains - eukaryotes, archaea and bacteria. The last two domains belong to prokaryotes. They probably took part in the emergence of eukaryotic cells (see “The Symbiogenesis Hypothesis” in Chapter 2 of this textbook). The modern superkingdom of eukaryotes is divided into three kingdoms - animals, fungi and plants.

The hierarchy of kingdoms is ranked into a sequence of decreasing categories - subkingdom (subregnum), type (phylum), class (classis), order (ordo), family (familia), genus (genus), view ( species). Along with these categories, intermediate ones are also used - suborder (subordo), superclass (superclassis), subclass (subclassis), superfamilia (superfamilia), subfamilia (subfamilia), tribe (tribus), subgenus (subgenus) and subspecies (subspecies). The ending “oidea” is used in the names of superfamilies, “idae” for families, “inae” for subfamilies and “ini” for tribes. According to some approaches, a phylum in the animal kingdom corresponds to a subdivision in the plant kingdom.

A species, being the main structural unit in the system of living organisms, turns out to be insufficient to determine the ranks of the groups that form it. Between the categories “species” and “race” there are intermediate forms. These include, for example, transitional stages of differentiation between geographical races and allopatric species, or between allopatric races and sympatric species. These intermediate groups are connected to each other by different levels of gene flow, which determines the intermediate nature of the variability between them. Within these groups, a mixture of characteristics similar to racial and species may arise. In one part of the species' range, groups can exist sympatrically, without interbreeding, in another - allotrically, but interbreed in some places of contact. Such groups are classified as subspecies. V. Grant (1980) called them “semi-species”.

The category “subspecies”, due to the complexity of determining its boundaries, genotypic structure and origin, is not generally accepted in taxonomy, but is widely used. Subspecies include collections of isolated populations of a species in which the majority of individuals differ in one or more characteristics from individuals of other populations of the same species. The Latin name of the subspecies is formed by adding a third word (subspecific epithet) to the name of the species. For example, red deer (Cervus elaphus), which is widespread in Europe and Asia, forms a number of subspecies in these territories. Its Central European subspecies (S. e. hippelaphus), in the mountainous Crimea - Crimean ( S.e. brauneri), in the Caucasus - Caucasian ( S.e. moral), in Altai and Sayan Mountains - Altai maral (S.e. sibiricus), in the Tien Shan and Dzungarian Alatau - Tien Shan deer (S.e. xanthopygos), in Transbaikalia, Amur and Ussuri territories - red deer (S.e. bactrianus).

Most modern classifications of the organic world use the cladistic method, based on the construction of a family tree. It is based on the degree of relationship without taking into account the geochronological sequence. Pedigree relationships are determined by methods of embryological, cytological, genetic and other studies that reflect the levels of evolution and degree of relationship. But without taking into account paleontological information (geochronology), it is impossible to construct a phylogenetic system of the organic world.

To date, no generally accepted taxonomy has been created. It is constantly updated according to the development of biology (Table 14). Related to this are different approaches to the number of kingdoms, subkingdoms and types (divisions) distinguished. Therefore, the system of the organic world is expressed in the form of a family tree, the branches of which are connected by kinship relationships corresponding to certain taxa, or as a list of taxon names presented in a hierarchical sequence (see “Directions and patterns of evolution” in Chapter 6 of this textbook).

Table 14

Development of taxonomy

E. Haeckel(E. Haeckel, 1935) Kingdoms	R. N. Whittaker et al., (1969) Kingdoms	S. Woese et al., (1977) Kingdoms	S. Woese, et al., (1990) Domains	T. Cavalier-Smith (1998)
				Domains	Kingdoms
Animals	Animals	Animals	Eukaryotes	Eukaryotes	Animals
Plants
	Plants	Plants			Plants
		Protozoa			Chromists (Protests)
Protests
		Bacteria	Bacteria		Bacteria

* I.A. Mikhailov and O.B. Bondarenko (1999) distinguishes the kingdoms of bacteria and cyanobacteria in the domain of prokaryotes

The science of classifying animals is called systematics or taxonomy. This science determines family relationships between organisms. The degree of relationship is not always determined by external similarity. For example, marsupial mice are very similar to ordinary mice, and tupai are very similar to squirrels. However, these animals belong to different orders. But armadillos, anteaters and sloths, completely different from each other, are united into one squad. The fact is that family ties between animals are determined by their origin. By studying the skeletal structure and dental system of animals, scientists determine which animals are closest to each other, and paleontological finds of ancient extinct species of animals help to more accurately establish family ties between their descendants. Plays a major role in the taxonomy of animals genetics- the science of the laws of heredity.

The first mammals appeared on Earth about 200 million years ago, separating from animal-like reptiles. The historical path of development of the animal world is called evolution. During evolution, natural selection occurred - only those animals survived that were able to adapt to environmental conditions. Mammals have evolved in different directions, forming many species. It happened that animals that had a common ancestor at some stage began to live in different conditions and acquired different skills in the struggle for survival. Their appearance was transformed, and changes useful for the survival of the species were consolidated from generation to generation. Animals whose ancestors looked the same relatively recently began to differ greatly from each other over time. Conversely, species that had different ancestors and went through different evolutionary paths sometimes find themselves in the same conditions and, changing, become similar. Thus, species unrelated to each other acquire common features, and only science can trace their history.

Classification of the animal world

The living nature of the Earth is divided into five kingdoms: bacteria, protozoa, fungi, plants and animals. Kingdoms, in turn, are divided into types. Exists 10 types animals: sponges, bryozoans, flatworms, roundworms, annelids, coelenterates, arthropods, molluscs, echinoderms and chordates. Chordates are the most progressive type of animals. They are united by the presence of a notochord, the primary skeletal axis. The most highly developed chordates are grouped into the vertebrate subphylum. Their notochord is transformed into a spine.

Kingdoms

Types are divided into classes. Total exists 5 classes of vertebrates: fish, amphibians, birds, reptiles (reptiles) and mammals (animals). Mammals are the most highly organized animals of all vertebrates. What all mammals have in common is that they feed their young with milk.

The class of mammals is divided into subclasses: oviparous and viviparous. Oviparous mammals reproduce by laying eggs, like reptiles or birds, but feed their young with milk. Viviparous mammals are divided into infraclasses: marsupials and placentals. Marsupials give birth to underdeveloped young, which are carried to term in the mother's brood pouch for a long time. In placentals, the embryo develops in the mother's womb and is born already formed. Placental mammals have a special organ - the placenta, which carries out the exchange of substances between the maternal body and the embryo during the period of intrauterine development. Marsupials and oviparous animals do not have a placenta.

Types of animals

Classes are divided into squads. Total exists 20 orders of mammals. In the oviparous subclass there is one order: monotremes, in the marsupial infraclass there is one order: marsupials, in the placental infraclass there are 18 orders: edentates, insectivores, woolly wings, chiropterans, primates, carnivores, pinnipeds, cetaceans, sirenians, proboscideans, hyraxes, aardvarks, artiodactyls, Callopods, lizards, rodents and lagomorphs.

Mammal class

Some scientists distinguish the independent order Tupaya from the order of primates, from the order of insectivores they separate the order Jumpers, and the predators and pinnipeds are combined into one order. Each order is divided into families, families into genera, and genera into species. In total, about 4,000 species of mammals currently live on earth. Each individual animal is called an individual.

A living organism is the main subject studied by a science such as biology. It is a complex system consisting of cells, organs and tissues. A living organism is one that has a number of characteristic characteristics. It breathes and feeds, moves or moves, and also has offspring.

Wildlife Science

The term “biology” was introduced by J.B. Lamarck, a French naturalist, in 1802. Around the same time and independently of him, the German botanist G.R. gave this name to the science of the living world. Treviranus.

Numerous branches of biology consider the diversity of not only currently existing, but also already extinct organisms. They study their origins and evolutionary processes, structure and function, as well as individual development and connections with the environment and with each other.

Branches of biology consider particular and general patterns that are inherent in all living things in all properties and manifestations. This applies to reproduction, metabolism, heredity, development, and growth.

The beginning of the historical stage

The first living organisms on our planet were significantly different in structure from those existing today. They were incomparably simpler. Throughout the entire stage of the formation of life on Earth, He contributed to the improvement of the structure of living beings, which allowed them to adapt to the conditions of the surrounding world.

At the initial stage, living organisms in nature fed only on organic components that arose from primary carbohydrates. At the dawn of their history, both animals and plants were the smallest single-celled creatures. They were similar to today's amoebas, blue-green algae and bacteria. In the course of evolution, multicellular organisms began to appear, which were much more diverse and complex than their predecessors.

Chemical composition

A living organism is one that is formed by molecules of inorganic and organic substances.

The first of these components includes water, as well as mineral salts. found in the cells of living organisms are fats and proteins, nucleic acids and carbohydrates, ATP and many other elements. It is worth noting the fact that living organisms contain the same components that objects have. The main difference lies in the ratio of these elements. Living organisms are those whose composition is ninety-eight percent hydrogen, oxygen, carbon and nitrogen.

Classification

The organic world of our planet today numbers almost one and a half million different animal species, half a million plant species, as well as ten million microorganisms. Such diversity cannot be studied without its detailed systematization. The classification of living organisms was first developed by the Swedish naturalist Carl Linnaeus. He based his work on the hierarchical principle. The unit of systematization was the species, the name of which was proposed to be given only in Latin.

The classification of living organisms used in modern biology indicates the kinship and evolutionary relationships of organic systems. At the same time, the principle of hierarchy is preserved.

A set of living organisms that have a common origin, the same chromosome set, are adapted to similar conditions, live in a certain area, freely interbreed with each other and produce offspring capable of reproduction, and is a species.

There is another classification in biology. This science divides all cellular organisms into groups according to the presence or absence of a formed nucleus. This

The first group consists of nuclear-free primitive organisms. Their cells have a nuclear zone, but it contains only a molecule. These are bacteria.

The true nuclear representatives of the organic world are eukaryotes. The cells of living organisms in this group possess all the main structural components. Their core is also clearly defined. This group includes animals, plants and fungi.

The structure of living organisms can be not only cellular. Biology studies other forms of life as well. These include non-cellular organisms such as viruses, as well as bacteriophages.

Classes of living organisms

In biological systematics, there is a rank of hierarchical classification, which scientists consider one of the main ones. He distinguishes classes of living organisms. The main ones include the following:

Bacteria;

Animals;

Plants;

Seaweed.

Description of classes

A bacterium is a living organism. It is a single cell that reproduces by division. The cell of a bacterium is enclosed in a membrane and has cytoplasm.

The next class of living organisms includes mushrooms. In nature, there are about fifty thousand species of these representatives of the organic world. However, biologists have studied only five percent of their total. Interestingly, fungi share some characteristics of both plants and animals. An important role of living organisms of this class lies in the ability to decompose organic material. This is why mushrooms can be found in almost all biological niches.

The animal world boasts great diversity. Representatives of this class can be found in areas where there would seem to be no conditions for existence.

The most highly organized class is warm-blooded animals. They got their name from the way they feed their offspring. All representatives of mammals are divided into ungulates (giraffe, horse) and carnivores (fox, wolf, bear).

Insects are also representatives of the animal world. There are a huge number of them on Earth. They swim and fly, crawl and jump. Many of the insects are so small that they are not able to withstand even water tension.

One of the first vertebrate animals to come onto land in distant historical times were amphibians and reptiles. Until now, the life of representatives of this class is connected with water. Thus, the habitat of adult individuals is land, and their breathing is carried out by the lungs. The larvae breathe through gills and swim in water. Currently, there are about seven thousand species of this class of living organisms on Earth.

Birds are unique representatives of the fauna of our planet. After all, unlike other animals, they are able to fly. Almost eight thousand six hundred species of birds live on Earth. Representatives of this class are characterized by plumage and egg laying.

Fish belong to a huge group of vertebrates. They live in bodies of water and have fins and gills. Biologists divide fish into two groups. These are cartilaginous and bone. Currently, there are about twenty thousand different species of fish.

Within the plant class there is its own gradation. Representatives of the flora are divided into dicotyledons and monocotyledons. In the first of these groups, the seed contains an embryo consisting of two cotyledons. Representatives of this species can be identified by their leaves. They are permeated with a network of veins (corn, beets). The embryo has only one cotyledon. On the leaves of such plants, the veins are arranged in parallel (onions, wheat).

The algae class has more than thirty thousand species. These are spore-dwelling plants that do not have blood vessels, but have chlorophyll. This component contributes to the process of photosynthesis. Algae do not form seeds. Their reproduction occurs vegetatively or by spores. This class of living organisms differs from higher plants in the absence of stems, leaves and roots. They only have a so-called body, which is called a thallus.

Functions inherent in living organisms

What is fundamental for any representative of the organic world? This is the implementation of energy and substance exchange processes. In a living organism, various substances are constantly converted into energy, and physical and chemical changes also occur.

This function is an indispensable condition for the existence of a living organism. It is thanks to metabolism that the world of organic beings differs from inorganic ones. Yes, changes in matter and transformation of energy also occur in inanimate objects. However, these processes have their fundamental differences. The metabolism that occurs in inorganic objects destroys them. At the same time, living organisms without metabolic processes cannot continue to exist. The consequence of metabolism is the renewal of the organic system. The cessation of metabolic processes entails death.

The functions of a living organism are varied. But all of them are directly related to the metabolic processes occurring in it. This can be growth and reproduction, development and digestion, nutrition and respiration, reactions and movement, excretion of waste products and secretion, etc. The basis of any body function is a set of processes of transformation of energy and substances. Moreover, this equally relates to the capabilities of both tissue, cell, organ, and the entire organism.

Metabolism in humans and animals includes the processes of nutrition and digestion. In plants it is carried out through photosynthesis. A living organism, when carrying out metabolism, supplies itself with substances necessary for existence.

An important distinguishing feature of objects in the organic world is the use of external energy sources. An example of this is light and food.

Properties inherent in living organisms

Any biological unit contains individual elements, which, in turn, form an inextricably linked system. For example, together all the organs and functions of a person constitute his body. The properties of living organisms are diverse. In addition to a single chemical composition and the possibility of carrying out metabolic processes, objects of the organic world are capable of organization. From chaotic molecular movement, certain structures are formed. This creates a certain orderliness in time and space for all living things. Structural organization is a whole complex of complex self-regulating ones that occur in a certain order. This allows you to maintain the constancy of the internal environment at the required level. For example, the hormone insulin reduces the amount of glucose in the blood when it is in excess. If there is a deficiency of this component, it is replenished by adrenaline and glucagon. Also, warm-blooded organisms have numerous mechanisms of thermoregulation. This includes dilation of skin capillaries and intense sweating. As you can see, this is an important function that the body performs.

The properties of living organisms, characteristic only of the organic world, are also contained in the process of self-reproduction, because the existence of any one has a temporary limitation. Only self-reproduction can sustain life. This function is based on the process of formation of new structures and molecules, determined by the information contained in DNA. Self-reproduction is inextricably linked with heredity. After all, each living creature gives birth to its own kind. Through heredity, living organisms transmit their developmental characteristics, properties and characteristics. This property is due to constancy. It exists in the structure of DNA molecules.

Another property characteristic of living organisms is irritability. Organic systems always respond to internal and external changes (impacts). As for the irritability of the human body, it is inextricably linked with the properties inherent in muscle, nervous, and glandular tissue. These components are able to give impetus to the response after muscle contraction, the sending of a nerve impulse, as well as the secretion of various substances (hormones, saliva, etc.). What if a living organism lacks a nervous system? The properties of living organisms in the form of irritability are manifested in this case by movement. For example, protozoa leave solutions in which the salt concentration is too high. As for plants, they are able to change the position of the shoots in order to absorb light as much as possible.

Any living systems can respond to a stimulus. This is another property of objects in the organic world - excitability. This process is ensured by muscle and glandular tissues. One of the final reactions of excitability is movement. The ability to move is a common property of all living things, despite the fact that outwardly some organisms lack it. After all, the movement of cytoplasm occurs in any cell. Attached animals also move. Growth movements due to an increase in the number of cells are observed in plants.

Habitat

The existence of objects in the organic world is possible only under certain conditions. Some portion of space invariably surrounds a living organism or an entire group. This is the habitat.

In the life of any organism, organic and inorganic components of nature play a significant role. They have a certain effect on him. Living organisms are forced to adapt to existing conditions. Thus, some of the animals can live in the Far North at very low temperatures. Others are able to exist only in the tropics.

There are several habitats on planet Earth. Among them are:

Terrestrial-aquatic;

Ground;

Soil;

Living organism;

Ground-air.

The role of living organisms in nature

Life on planet Earth has existed for three billion years. And during all this time, organisms developed, changed, settled and at the same time influenced their habitat.

The influence of organic systems on the atmosphere caused the appearance of more oxygen. At the same time, the volume of carbon dioxide decreased significantly. Plants are the main source of oxygen production.

Under the influence of living organisms, the composition of the waters of the World Ocean has also changed. Some rocks are of organic origin. Minerals (oil, coal, limestone) are also the result of the functioning of living organisms. In other words, objects of the organic world are a powerful factor that transforms nature.

Living organisms are a kind of indicator indicating the quality of the human environment. They are connected by complex processes with vegetation and soil. If even a single link from this chain is lost, there will be an imbalance in the ecological system as a whole. That is why for the circulation of energy and substances on the planet it is important to preserve all the existing diversity of representatives of the organic world.

Since ancient times, observing animals, people have noticed similarities and differences in their structure, behavior, and living conditions. Based on their observations, they divided animals into groups, which helped them understand the system of the living world. Today, man's desire to systematically understand the animal world has become the science of classifying living organisms - taxonomy.

Principles of taxonomy

The foundations of modern taxonomy were laid by the scientists Lamarck and Linnaeus.

Lamarck proposed the principle of relatedness as a basis for assigning animals to one group or another. Linnaeus introduced binary nomenclature, that is, a double name for the species.

Each type in the name has two parts:

• genus name;
• species name.

For example, pine marten. Marten is the name of a genus, which may include many species (stone marten, etc.).

Lesnaya is the name of a specific species.

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Linnaeus also proposed the main taxa, or groups, that we still use today.

View

The species is the initial element of classification.

Organisms are classified as one species according to a number of criteria:

• similar structure and behavior;
• identical set of genes;
• similar ecological living conditions;
• free interbreeding.

The species can be very similar in appearance. Previously, it was believed that the malaria mosquito was one species, but now it has been found that there are 6 species that differ in the structure of their eggs.

Genus

We usually name animals by gender: wolf, hare, swan, crocodile.

Each of these genera may contain many species. There are also genera containing only one species.

Rice. 1. Types of bears.

Differences between species of a genus can be obvious, as between a brown and a polar bear, and completely invisible, as between twin species.

Family

Genera are united into families. The family name may be derived from the generic name, e.g. mustelids or bearish.

Rice. 2. The cat family.

Also, the name of the family can indicate the structural features or lifestyle of animals:

• lamellar;
• bark beetles;
• cocoon worms;
• dung flies.

Related families are collected into orders.

Units

Rice. 3. Order Chiroptera.

For example, the order Carnivores includes animals that are different in structure and lifestyle, such as:

• weasel;
• polar bear;
• fox.

If there is a good harvest of berries and mushrooms, a brown bear from the order of carnivores may not hunt for a long time, while a hedgehog from the order of insectivores hunts almost every night.

Class

Classes are numerous groups of animals. For example, the class of Gastropods has about 93 thousand species, and the class of open-jawed insects has more than a million.

Moreover, new species of insects are discovered every year. According to some biologists, there may be from 2 to 3 million species in this class.

Phylums are the largest taxa. The most important of them:

• chordates;
• arthropods;
• shellfish;
• annelids;
• flatworms;
• roundworms;
• sponges;
• coelenterates.

The most voluminous taxa are kingdoms.

All animals are united in the animal kingdom.

We present the main systematic groups in the table “Classification of Animals”.

Discrepancies

Scientists have different views on the classification of the animal world. Therefore, textbooks often classify a certain group of animals as different taxa.

For example, single-celled animals are sometimes classified as the Kingdom of Protists, and are sometimes considered animals of the protozoan type.

Additional classification elements are often introduced with the prefixes over-, under-, infra-:

• subtype;
• superfamily;
• infraclass and others.

For example, crustaceans were previously considered a class in the phylum Arthropods. In the new books they are considered a subtype.

What have we learned?

The science of taxonomy deals with the classification of species of animals and other organisms. Having studied this topic in 7th grade biology, we learned the main and additional taxa into which lower-order taxa are grouped. Animals are classified according to certain characteristics. The higher the order of the taxon, the more general the characters will be.

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