Nematodes (lat. Nematoda, Nematodes) or roundworms are the second largest group of multicellular animals on Earth (after arthropods), distinguished by their appearance and structure. Formally, they belong to primary cavity worms, but this is already an outdated classification.

Morphology

Nematodes are structurally simple organisms. Adult nematodes are composed of approximately 1000 somatic cells, as well as hundreds of cells associated with the reproductive system. These roundworms have been characterized as a tube-in-tube based gastrointestinal tract that runs from the mouth at the anterior end to the anus near the tail. Nematodes possess digestive, nervous, excretory, and reproductive systems, but do not have a dedicated circulatory or respiratory system. They range in size from 0.3 mm to over 8 meters.

reproduction

Most of the nematode species are dioecious with separate male and female individuals. Although some, such as Caenorhabditis elegans, have androdiecia, they are represented by hermaphrodites and males. Both sexes have one or two tubular gonads (ovaries and testes, depending on the sex).

Reproduction of nematodes is usually based on mating, although hermaphrodites are capable of self-fertilization. Males are usually smaller than females or hermaphrodites, and often have a distinctive curved or fan-shaped tail to hold onto the opposite sex. During mating, one or more chitinous spicules emerge from the cloaca and are inserted into the female's genital opening. This is how the seminal fluid is transmitted, which during the process passes along the length of the entire male.

Due to the lack of knowledge about many nematodes, their taxonomy is controversial and has changed many times. In different sources, you can find very different classifications. In most of them, according to outdated information, nematodes are distinguished as a class, although they are already classified as a separate type, including several classes. But there is still controversy about this.

It used to be a suborder, but is now separated as a separate detachment.

All these suborders include several families, which, in turn, are divided into genera, and those into species.

Habitat

Roundworms can adapt to any ecosystem, so they can be found in fresh and salt water, soil, in the polar regions and in the tropics. Nematodes are ubiquitous. Scientists have found worms in every part of the earth's lithosphere.

Human infection

Live roundworm in human intestine during colonoscopy

Roundworms enter the body:

When nematodes infect a person, he has the following symptoms:

1. Chair problems.
2. Vomiting and nausea.
3. Appetite disappears.
4. Dark circles under the eyes.
5. Itching in the anus.

In the future, nematodes begin to penetrate into many human organs and actively multiply. As a result, a person begins to feel severe weakness, an allergic reaction may develop, in rare cases, mental abnormalities, and so on. Nematodes in humans greatly reduce immunity.

Animal infection

A person can become infected with nematodes from cats, dogs and other animals, if basic hygiene rules are not followed.

Nematode diseases in plants

Brown stripes on a potato stem caused by the Trichodoride nematode.

The most famous types are:

Particular attention is paid to a highly specialized worm species, the golden potato nematode (Globodera rostochiensis). With a sign, almost everyone who grew plants of the nightshade family at home or in the country. They prefer to settle on the roots of potatoes and tomatoes. The individual develops into a rhizome. Cysts are spread by soil, wind, water, and infected tubers. Therefore, when a potato nematode is detected, the infection zone is closed for quarantine.

You should know that the golden potato nematode, like other similar plant pests, is absolutely safe for humans.

Free-living nematodes

In free-living species, development usually consists of four cuticle molts during growth. Various species of these nematodes feed on a very diverse diet - algae, fungi, small animals, feces, dead organisms and living tissues. Free-living marine nematodes are important and abundant members of the meiobenthos (meiofauna, i.e. bottom-dwelling organisms). They play an important role in the decomposition process, aid in the breakdown of nutrients in the marine environment, and are sensitive to changes due to pollution. Of note is the soil-dwelling roundworm Caenorhabditis elegans, which has become a model organism for scientists; used in various experiments. This is due to the fact that its genome (a set of genes) has been fully studied for a long time, and this makes it possible to observe changes in the body during manipulations with genes.

Biological diversity (biodiversity) is a concept that refers to the diversity of life on Earth and all existing natural systems. Biodiversity is recognized as one of the foundations of human life. The role of biodiversity is enormous - from stabilizing the earth's climate and restoring soil fertility to providing people with products and services, which allows us to maintain the well-being of society, and, in fact, allows life to exist on Earth.

The diversity of living organisms around us is very significant, and the level of knowledge about it is still not great. Today, science knows (described and received scientific names) about 1.75 million species, but it is estimated that at least 14 million species may exist on our planet.

Russia has significant biodiversity, while the unique feature of our country is the presence of large underdeveloped natural areas, where most of the ecological processes retain their natural character. Russia owns 25% of all virgin forests on the planet. In Russia, there are 11,500 species of wild plants, 320 species of mammals, 732 species of birds, 269 species of freshwater fish, and about 130,000 species of invertebrates. There are many endemics, species living only on the territory of our country. Our forests make up 22% of all forests in the world.

It is the topic "The role of diversity in wildlife" that this essay is devoted to.

1.

It is obvious to any of us that we are all different and that the world around us is diverse. However, not everyone would think to ask a seemingly simple question - why is this so? Why do we need diversity and what role does it play in everyday life?

And if you think about it seriously, it turns out that:

Diversity is progress, development, evolution. Something new can only be obtained from different things - atoms, thoughts, ideas, cultures, genotypes, technologies. If everything around is the same, then where does the new come from? Imagine that our Universe consists only of identical atoms (for example, hydrogen) - how could you and I be born at the same time?

Diversity is sustainability. It is the mutual and coordinated actions of components with different functions that give any complex system the ability to resist external influences. A system of identical elements is like pebbles on a beach - it is stable only until the next incoming wave.

Diversity is life. And we live in a series of generations solely due to the fact that we all have different genotypes. It is no coincidence that from time immemorial all religions of the world have imposed the strictest taboo on marriages with close relatives. This preserved the genetic diversity of the population, without which there is a direct path to degeneration and disappearance from the face of the earth.

If we now imagine that diversity has disappeared in the world, then with it we will lose:

A) the ability to develop;

B) stability;

c) life itself.

Creepy picture, isn't it?

That is, having asked a seemingly naive question, we come to an unexpected conclusion for many: variety - determining factor in the existence of all life on our planet.

Mankind, which imagines itself to be the "kings of nature", easily, without hesitation, wipes off the face of the earth "objectionable" species to us. We destroy entire species of plants and animals - completely, irrevocably, forever. We are destroying natural diversity and at the same time investing huge sums in cloning - the artificial creation of identical individuals ... And we call this biotechnology, the science of the future, with which we associate all hopes for further existence. What are the prospects for such an existence is clear from the previous paragraph - do not be lazy, re-read it again ...

At one time, we felt on ourselves both the “only true doctrine”, and the “society of universal equality”, and at the cost of millions of lives we were like “in a single ranks” ... In the socio-economic sphere, life has taught us to appreciate diversity, but is it necessary to go through even more ordeals to learn to appreciate biological diversity?

Biodiversity is defined by the World Wide Fund for Nature (1989) as “the entire diversity of life on earth, the millions of species of plants, animals, micro-organisms with their gene sets, and the complex ecosystems that make up wildlife”. Thus, biodiversity should be considered at three levels. Biological diversity at the species level covers the entire range of species on Earth from bacteria and protozoa to the kingdom of multicellular plants, animals and fungi. On a smaller scale, biological diversity includes the genetic diversity of species, both from geographically distant populations and from individuals within the same population. Biological diversity also includes the diversity of biological communities, species, ecosystems formed by communities and the interactions between these levels For the continuous survival of species and natural communities, all levels of biological diversity are necessary, all of them are important for humans. Species diversity demonstrates the richness of evolutionary and ecological adaptations of species to different environments. Species diversity serves as a source of diverse natural resources for humans. For example, tropical rainforests, with their richest array of species, produce a remarkable variety of plant and animal products that can be used for food, construction, and medicine. Genetic diversity is necessary for any species to maintain reproductive viability, resistance to diseases, and the ability to adapt to changing conditions. The genetic diversity of domestic animals and cultivated plants is especially valuable to those working on breeding programs to maintain and improve modern agricultural species.

Community-level diversity is the collective response of species to different environmental conditions. The biological communities found in deserts, steppes, forests and floodlands maintain the continuity of the normal functioning of the ecosystem by providing “maintenance” for example through flood control, soil erosion protection, air and water filtration.

Species diversity

At every level of biological diversity - species, genetic and community diversity, experts study the mechanisms that change or maintain diversity. Species diversity includes the entire set of species that live on Earth. There are two main definitions of the concept of species. First: a species is a collection of individuals that differs from other groups in one or another morphological, physiological or biochemical characteristics. This is the morphological definition of the species. Differences in DNA sequences and other molecular markers are increasingly being used to distinguish between species that are virtually identical in appearance (such as bacteria). The second definition of a species is a set of individuals between which there is free interbreeding, but there is no interbreeding with individuals of other groups (the biological definition of a species).

The inability to clearly distinguish one species from another due to the similarity of their characteristics, or the resulting confusion in scientific names, often reduces the effectiveness of species protection efforts.

Only 10–30% of the world's species have now been described by biologists, and many may become extinct before they are described.

Any biodiversity conservation strategy requires a good understanding of how many species there are and how those species are distributed. To date, 1.5 million species have been described. At least twice as many species remain undescribed, mainly insects and other tropical arthropods.

Our knowledge of the number of species is not accurate, since many non-showy animals have not yet come to the attention of taxonomists. For example, small spiders, nematodes, soil fungi and insects living in the crowns of tropical forest trees are difficult to study; various currents are found, but the boundaries of these areas are usually unstable over time.

These little-studied groups can number hundreds and thousands, even millions of species. Bacteria are also very poorly studied. Because of the difficulty in growing and identifying them, microbiologists have only been able to identify about 4,000 species of bacteria. However, research conducted in Norway on bacterial DNA analysis shows that more than 4,000 species of bacteria can be present in one gram of soil, and about the same number can be found in marine sediments. Such high diversity, even in small samples, implies the existence of thousands or even millions of as yet undescribed bacterial species. Modern research is trying to determine what is the ratio of the number of widespread species of bacteria compared to regional or narrow local species.

genetic diversity

Genetic intraspecific diversity is often provided by the reproductive behavior of individuals within a population. A population is a group of individuals of the same species that exchange genetic information among themselves and give fertile offspring. A species may include one or more distinct populations. A population can consist of a few individuals or millions.

Individuals within a population are usually genetically distinct from each other. Genetic diversity is due to the fact that individuals have slightly different genes - sections of chromosomes that encode certain proteins. Variants of a gene are known as its alleles. Differences arise from mutations - changes in the DNA that is located on the chromosomes of a particular individual. Alleles of a gene can affect the development and physiology of an individual in different ways. Breeders of plant varieties and animal breeds, by selecting certain gene variants, create high-yielding, pest-resistant species, such as crops (wheat, corn), livestock and poultry.

Diversity of communities and ecosystems

A biological community is defined as a collection of individuals of different species living in a certain area and interacting with each other. Examples of communities are coniferous forests, tall grass prairies, tropical rainforests, coral reefs, deserts. A biological community together with its environment is called an ecosystem. In terrestrial ecosystems, water is evaporated by biological objects from the surface of the Earth and from water surfaces in order to shed again in the form of rain or snow and replenish the terrestrial and aquatic environments. Photosynthetic organisms absorb light energy, which is used by plants for their growth. This energy is absorbed by animals that eat photosynthetic organisms or is released in the form of heat both during the life of organisms and after their death and decomposition.

The physical properties of the environment, especially the annual temperature and precipitation regime, influence the structure and characteristics of the biological community and determine the formation of either a forest, or a meadow, or a desert or a swamp. The biological community, in turn, can also change the physical characteristics of the environment. In terrestrial ecosystems, for example, wind speed, humidity, temperature and soil characteristics can be influenced by the plants and animals that live there. In aquatic ecosystems, such physical characteristics as turbulence and transparency of water, its chemical characteristics and depth determine the qualitative and quantitative composition of aquatic communities; and communities such as coral reefs themselves greatly influence the physical properties of the environment. Within a biological community, each species uses a unique set of resources that constitutes its niche. Any niche component can become a limiting factor when it limits the size of a population. For example, populations of bat species with highly specialized environmental requirements that form colonies only in limestone caves may be limited by the number of caves with suitable conditions.

The composition of communities is largely determined by competition and predators. Predators often significantly reduce the number of species - their prey - and may even displace some of them from their usual habitats. When predators are exterminated, the population of their prey can rise to a critical level or even exceed it. Then, after the exhaustion of the limiting resource, the destruction of the population may begin.

The community structure is also determined by symbiotic (in the broadest sense of the word) relationships (including mutualistic ones), in which species are in mutually beneficial relationships. Mutualistic species achieve greater density when living together. Common examples of such mutualism are plants with fleshy fruits and birds that feed on these fruits and spread their seeds; fungi and algae, which together form lichens; plants that give shelter to ants, supplying them with nutrients; coral polyps and the algae that live in them.

Tropical rainforests, coral reefs, vast tropical lakes and deep seas are the most species-rich. The biological diversity is also great in dry tropical regions with their deciduous forests, bush bushes, savannahs, prairies and deserts. In temperate latitudes, shrub-covered territories with a Mediterranean type of climate are distinguished by high rates. They are found in South Africa, southern California and southwestern Australia. Tropical rainforests are primarily characterized by an exceptional diversity of insects. On coral reefs and in deep seas, diversity is due to a much wider range of taxonomic groups. The diversity in the seas is associated with their great age, gigantic areas and the stability of this environment, as well as with the peculiarity of the types of bottom sediments. The remarkable diversity of fish in large tropical lakes and the emergence of unique species on islands is due to evolutionary radiation in isolated productive habitats.

The species diversity of almost all groups of organisms increases towards the tropics. For example, Thailand has 251 species of mammals, while France has only 93, despite the fact that the areas of both countries are approximately the same.

2. DIVERSITY OF LIVING ORGANISMS IS THE BASIS OF THE ORGANIZATION AND STABILITY OF THE BIOSPHERE

The biosphere is a complex outer shell of the Earth, inhabited by organisms that together make up the living substance of the planets. It can be said that the biosphere is an area of ​​active life, covering the lower part of the atmosphere, the upper part of the lithosphere and the hydrosphere.

Huge species diversity. living organisms provides a constant mode of biotic circulation. Each of the organisms enters into specific relationships with the environment and plays its role in the transformation of energy. This has formed certain natural complexes, which have their own specifics depending on environmental conditions in one or another part of the biosphere. Living organisms inhabit the biosphere and are included in one or another biocenosis - spatially limited parts of the biosphere - not in any combination, but form certain communities of species adapted to cohabitation. Such communities are called biocenoses.

The relationship between predator and prey is particularly complex. On the one hand, predators, destroying domestic animals, are subject to extermination. On the other hand, predators are necessary to maintain the ecological balance (“Wolves are the orderlies of the forest”).

An important ecological rule is that the more heterogeneous and complex the biocenoses, the higher the stability, the ability to withstand various external influences. Biocenoses are distinguished by great independence. Some of them persist for a long time, others naturally change. Lakes turn into swamps - peat is being formed, and as a result, a forest grows on the site of the lake.

The process of regular changes in the biocenosis is called succession. Succession is a successive change of some communities of organisms (biocenoses) by others in a certain area of ​​​​the environment. In a natural course, succession ends with the formation of a stable community stage. In the course of succession, the diversity of the species of organisms that make up the biocenosis increases, as a result of which its stability increases.

The increase in species diversity is due to the fact that each new component of the biocenosis opens up new opportunities for invasion. For example, the appearance of trees allows species living in the subsystem to penetrate into the ecosystem: on the bark, under the bark, building nests on branches, in hollows.

In the course of natural selection, only those types of organisms that can reproduce most successfully in this particular community are inevitably preserved in the composition of the biocenosis. The formation of biocenoses has an essential side: "competition for a place under the sun" between different biocenoses. In this “competition”, only those biocenoses are preserved that are characterized by the most complete division of labor between their members, and, consequently, richer internal biotic connections.

Since each biocenosis includes all the main ecological groups of organisms, it is equal in its capabilities to the biosphere. The biotic cycle within the biocenosis is a kind of reduced model of the Earth's biotic cycle.

Thus:

1. The stability of the biosphere as a whole, its ability to evolve is determined by the fact that it is a system of relatively independent biocenoses. The relationship between them is limited to connections through non-living components of the biosphere: gases, atmosphere, mineral salts, water, etc.

2. The biosphere is a hierarchically built unity, including the following levels of life: individual, population, biocenosis, biogeocenosis. Each of these levels has a relative independence, and only this ensures the possibility of the evolution of the entire large macrosystem.

3. The diversity of life forms, the relative stability of the biosphere as a habitat and the life of individual species create the prerequisites for a morphological process, an important element of which is the improvement of behavioral responses associated with the progressive development of the nervous system. Only those species of organisms have survived that, in the course of the struggle for existence, began to leave offspring, despite the internal restructuring of the biosphere and the variability of cosmic and geological factors.

3. THE PROBLEM OF CONSERVATION OF DIVERSITY IN NATURE AS A FACTOR OF SURVIVAL OF HUMANITY

At the turn of the third millennium, we bitterly state that as a result of anthropogenic pressure, especially in recent decades, the number of plant and animal species is sharply decreasing, their gene pool is depleted, the areas of the most productive ecosystems are shrinking, and environmental health is deteriorating. The constant expansion of the lists of rare and endangered species of biota in new editions of the Red Books is a direct evidence of this. According to some forecasts of leading ornithologists, by the end of the 21st century, every eighth bird species will disappear on our planet.

Awareness of the need to preserve all species from the kingdoms of fungi, plants and animals, as the basis for the existence and well-being of mankind itself, served as a decisive incentive for the development and implementation of a number of major international and national programs, as well as the adoption of fundamental interstate agreements in the field of environmental protection and monitoring, plant and the animal world. After the signing and subsequent ratification by more than 170 states of the International Convention on Biodiversity (1992, Rio de Janeiro), much more attention has been paid to the study, conservation and sustainable use of biological resources in all countries of the world. In accordance with the basic requirements of the Convention on Biological Diversity, which Russia ratified in 1995, it was necessary to provide "scientific support" for decision-making in the field of wildlife conservation in-situ and ex-situ. Everything related to the inventory, assessment of the state, conservation, restoration and rational use of objects of flora and fauna requires a clear scientific justification. For the vast territory of Russia with its landscape diversity, multinational population, various traditions in the use of natural resources, a much more active development of fundamental research is necessary, without which, in principle, it is impossible to carry out an inventory and develop a coordinated strategy for the protection of all categories of biodiversity, at all its hierarchical levels.

The problem of biodiversity conservation is today one of the central problems of ecology, since life itself on Earth is compensated only with a sufficient variety of evolutionary material. It is thanks to biological diversity that the structural and functional organization of ecological systems is created, ensuring their stability over time and resistance to changes in the external environment. According to the figurative definition of Corr. RAS A.F. Alimova: “The whole set of biological sciences studies four main phenomena: life, organism, biosphere and biodiversity. The first three form a series from life (at the base) to the biosphere (above), the fourth penetrates into the first three: without a variety of organic molecules there is no life, without a morphological and functional diversity of cells, tissues, organs, and in unicellular - organelles - there is no organism, without the diversity of organisms, there can be no ecosystems and no biosphere.” In this regard, it seems very logical to study biodiversity not only at the species level, but at the level of populations, communities, and ecosystems. As the anthropogenic impact on nature intensifies, ultimately leading to the depletion of biological diversity, the study of the organization of specific communities and ecosystems, as well as the analysis of changes in their biodiversity, becomes really important. One of the most important causes of biodiversity degradation is the underestimation of its real economic value. Any proposed options for biodiversity conservation are constantly losing competition with forestry and agriculture, the mining industry, since the benefits from these sectors of the economy are visible and tangible, they have a price. Unfortunately, neither the centrally planned economy nor the modern market economy could and cannot correctly determine the true value of nature. At the same time, a group of experts led by Robert Constatz (University of Maryland) identified 17 categories of functions and services of nature, among which were climate regulation, atmospheric gas composition, water resources, soil formation, waste processing, genetic resources, etc. The calculations of these scientists gave a total estimate of these functions of nature at an average of 35 trillion. dollars, which is twice the GNP created by mankind (18 trillion dollars a year). We still do not pay due attention to this area of ​​research to determine the value of biodiversity, which does not allow us to create a reliable economic mechanism for protecting the environment in the republic.

Among the priority areas of scientific research for the coming decades for the purposes of biodiversity conservation in the European North-East of Russia, the following should be highlighted:

— unification of existing and development of new methods for assessing and inventorying all components of biodiversity;

— creation of computer databases on biodiversity in the context of individual taxa, types of ecosystems, forms of use of biodiversity components, including databases on rare plant and animal species;

– development and implementation of the latest methods of taxonomy in the systematics and diagnostics of plants, animals, fungi and microorganisms;

– continuation of the inventory of the biota of the region, and especially in specially protected natural areas;

— preparation and publication of new regional floristic and faunal summaries, atlases, catalogs, guides, monographs on individual taxa of microorganisms, fungi, lower and higher plants, vertebrates and invertebrates;

— development of methodological foundations for the economic assessment of biodiversity;

— development of scientific bases and technologies for the restoration of biological diversity in anthropogenically disturbed terrestrial, water and soil ecosystems; — preparation of a regional program for the conservation of biodiversity, taking into account the specifics of the diverse conditions of our country.

CONCLUSION

Mankind has recognized the great importance of biological diversity and its components by adopting the Convention on Biological Diversity on June 5, 1992. It has become one of the most massive international conventions; today 187 countries are its members. Russia has been a party to the Convention since 1995. With the adoption of this Convention, a global approach to the conservation and sustainable use of the entire wealth of living organisms on Earth was adopted for the first time. The Convention recognizes the need for a multi-sectoral and integrated approach for the sustainable use and conservation of biodiversity, the special role of the international exchange of information and technology in this area, and the importance of a fair and equitable distribution of benefits derived from the use of biological resources. It is these three components - sustainable use of biodiversity, conservation of biodiversity, equitable distribution of benefits from the use of genetic resources - that make up the "three pillars" of the Convention.

Looking out the window or walking along the street, you can endlessly admire the beauty of the surrounding nature. And all this beauty is mainly made up of plants. So diverse, bright, lively and juicy, they simply beckon to touch them, enjoy their aroma and admire their magnificence to their heart's content.

Variety of plant organisms

Oh, what a variety of plants there is! In total, today there are over 350 thousand species of these unique creatures of nature. All of them are not the same both in external structure and in lifestyle and internal features.

The plants occupy an entire kingdom. The simplest classification for these organisms would be:

• lower (the body is not divided into organs, these are algae and lichens);
• higher (the body is divided into organs, these are those that have a root, stem and leaves).

In turn, the species diversity of plants of the highest category is manifested in the division into the following groups:

1. Spores (mosses,
2. Gymnosperms (coniferous, ginkgo, cycad).
3. Angiosperms, or flowering.

Each systematic group has its own classes, genera and species, which is why the diversity of plants on our planet is so great.

life forms

One of the most important signs by which representatives of the flora differ from each other is their appearance. It is this feature that underlies the classification by life forms. The diversity of plants can be seen if they are classified into groups:

1. Trees (coniferous: pine, spruce, fir and others; deciduous: birch, oak, poplar, apple tree and others).
2. Shrubs (lilac, hazel, honeysuckle, etc.).
3. Shrubs (currant, wild rose, raspberry).
4. Semi-shrubs (wormwood, astragalus, teresken, saltwort).
5. Semi-shrubs (lavender, sage).
6. Herbs (feather grass, sedge, forget-me-nots, kupena, lilies of the valley, and so on).

This classification covers only higher angiosperms, which are the majority on the planet.

Seaweed

The diversity of plants and animals in the seas and oceans has always been admired by all researchers and simply lovers of the underwater world. Beautiful and unusual, bright, dangerous and defenseless, they make up a whole world, not fully explored, and therefore alluring and mysterious.

What representatives of the flora are found here? These are algae and aquatic plants that stay near the surface of the water or are immersed in it with roots and part of the stems.

Algae are divided into several departments:

1. Blue-green (for example, cyanobacteria).
2. Green unicellular (chlamydomonas, volvox).
3. Green multicellular (ulotrix, spirogyra, ulva).
4. (fucus, kelp, sargassum).
5. Red (porphyry, radimeria).

The main distinguishing features of these plants are that their body (in multicellular representatives) is not divided into organs. It is represented by thallus and rhizoids, which perform the function of attachment to the substrate.

blooming aquatic species

The diversity of aquatic plant species is not limited to algae. A lot of beautiful flowering representatives delight with their magnificence, floating on the surface of the water or plunging into it only partly.

These include:

• different types of water lilies;
• calla;
• vodokras ordinary;
• bulrush;
• tail;
• loosestrife monetized;
• host;
• needle swamp;
• manna;
• urinate the water;
• Siberian iris;
• buttercup water;
• calamus marsh and many others.

The variety of plants in salt and fresh water bodies is so great that it is possible to create entire landscapes, both artificial and natural. People use representatives of the flora to decorate aquariums, design ponds and other artificial sources.

Spore

This group includes about 43 thousand species from various departments. The main ones are as follows:

• Bryophytes (liver mosses, anthocerotes, bryophytes);
• Lycopsoid (moss);
• Horsetails (horsetails).

The main feature is the method of reproduction, which is reduced to the formation of specialized cells - spores. It is also interesting that these plants live by alternating generations in the development cycle: the sexual generation of the gametophyte is replaced by the asexual sporophyte, and vice versa. Such representatives are not able to bloom and form seeds and fruits, and therefore belong to the category of spores. Their life is very dependent on water, since reproduction occurs only in a humid environment.

Representatives are of great economic importance and are widely used not only in nature, but also in human life. Decorative, medicinal use is their significance for people.

Conifers

Conifers include plants that have the following features:

• in a special needle shape and are called "needles";
• the life form of these plants are trees and shrubs;
• the internal composition is replete with essential oils, resins and terpenes;
• seeds are formed, but flowers never appear;
• the seed is enclosed in cone scales and is bare, hence the other name - Gymnosperms.

There are a lot of species of coniferous trees, about 630. They make a great contribution to the overall diversity of the plant world, are long-lived and valuable tree species. According to some reports, there are pine trees that are over 5,000 years old! The appearance of conifers very much enlivens any area, delights and fascinates with its grandeur. The most common types can be called:

• pines;
• cedars;
• larches;
• cypresses;
• juniper;

One of the main attractive features of these plants is that they are evergreen and do not shed their leaves during the winter cold (the exception is larch).

Flowering or angiosperms

This is the most numerous of all the currently known groups of plants, which is estimated at more than 280 thousand species. The main feature is the formation in which there are special structures adapted for reproduction.

The flower develops an ovary and a seed, which is then protected by the tissue of the fruit. That is why these plants are called angiosperms. The flowers themselves are so diverse in appearance, shape, color of the corolla, size that one can only admire and be surprised.

Of great importance among flowering plants is given to medicinal plants. They help people and animals in the fight against various diseases, affect almost all body systems.

The classification of flowering plants is extensive, so we will consider only the most common families of the two main classes - monocots and dicots.

1. Monocots: cereals (rye, wheat, oats, sorghum, millet, corn), lilies (tulips, lilies, hazel grouse), bulbous (onions, garlic, perennial meadow grasses).
2. Dicotyledons: Rosaceae (rose hips, pears, plums, apples, raspberries, strawberries, roses), butterflies or legumes (peanuts, lupins, acacia, soybeans, peas, clover, beans, beans), cruciferous (cabbage, rapeseed, mustard, horseradish , radish), nightshade (tomatoes or tomatoes, peppers, nightshade, eggplant, petunia and others), Compositae (dandelions, chamomile, cornflowers, sunflowers, coltsfoot and others).

The variety of flowering plants is so great that it is, of course, impossible to cover them all in one article. After all, each family has hundreds and thousands of species, has its own individual characteristics in structure and appearance.

poisonous plants

Unfortunately, despite the unsurpassed beauty, many plants have strong toxic properties, that is, they are poisonous, contain substances in various concentrations that can paralyze or kill a person, animals, any other living creatures.

It is worth introducing children to such representatives from childhood so that they understand how dangerous the world around them can be. The variety of poisonous plants is quite large, there are thousands of species. To name just a few common representatives:

• snowdrop snow;
• hyacinth orientalis;
• autumn colchicum;
• daffodils;
• amaryllis;
• May lily of the valley;
• soporific poppy;
• the dicentra is magnificent;
• common buttercup;
• irises;
• dieffenbachia;
• rhododendrons;
• oleanders and many more.

Obviously, medicinal plants can be attributed to the same group. In an increased dose, any medicine can become a poison.

insectivorous flowers

Some plants of the tropics and the equatorial part of the planet are interesting in terms of the way they feed. They are insectivorous and emit not a pleasant and exciting aroma, but a fetid smell. Main types:

• Venus flytrap;
• sundew;
• nepenthes;
• sarracenia;
• pemphigus;
• zhiryanka.

Outwardly, they are very interesting in shape and bright in color. They have different mechanisms and devices for capturing and digesting insects and small rodents.

>>Diversity of plants

§ 5. Diversity of plants

Plants differ from each other in color and shape of stems, leaves, flowers and fruits, life expectancy and other features.

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The living nature around us in all its diversity is the result of a long historical development of the organic world on Earth, which began almost 3.5 billion years ago.

The biological diversity of living organisms on our planet is great.

Each species is unique and unrepeatable.

For example, there are more than 1.5 million species of animals. However, according to some scientists, only in the class of insects there are at least 2 million species, the vast majority of which are concentrated in the tropical zone. The number of animals of this class is also large - it is expressed in numbers with 12 zeros. And different unicellular planktonic organisms can contain up to 77 million individuals in only 1 m 3 of water.

Tropical rainforests are particularly biodiverse. The development of human civilization is accompanied by an increase in anthropogenic pressure on the natural communities of organisms, in particular, the destruction of the greatest tracts of Amazonian forests, which leads to the disappearance of a number of animal and plant species, to a decrease in biodiversity.

Amazonia

To understand all the diversity of the organic world helps a special science - systematics. Just as a good collector classifies the objects he collects according to a certain system, a taxonomist classifies living organisms on the basis of signs. Every year, scientists discover, describe and classify new species of plants, animals, bacteria, etc. Therefore, taxonomy as a science is constantly evolving. So, in 1914, a representative of a then unknown invertebrate animal was described for the first time, and only in 1955 did the domestic zoologist A.V. Ivanov (1906-1993) substantiate and prove that it belongs to a completely new type of invertebrates - gonophores.

A.V. Ivanov

Pogonophores

Development of taxonomy (creation of artificial classification systems).

Attempts to classify organisms were made by scientists in ancient times. The outstanding ancient Greek scientist Aristotle described over 500 species of animals and created the first classification of animals, dividing all animals known at that time into the following groups:

I.Animals without blood: soft-bodied (corresponds to cephalopods); soft-shelled (crustaceans); insects; cranioderms (shell molluscs and echinoderms).

II. Animals with blood: viviparous quadrupeds (corresponds to mammals); birds; oviparous quadrupeds and legless (amphibians and reptiles); viviparous legless with pulmonary breathing (cetaceans); scaly, legless, breathing with gills (fish).

By the end of the XVII century. a huge amount of material was accumulated on the diversity of forms of animals and plants, which required the introduction of an idea of ​​the species; this was first done in the work of the English scientist John Ray (1627-1705). He defined a species as a group of morphologically similar individuals and tried to classify plants based on the structure of the vegetative organs. However, the famous Swedish scientist Carl Linnaeus (1707-1778), who in 1735 published his famous work The System of Nature, is rightfully considered the founder of modern taxonomy. K. Linney took the structure of a flower as the basis for the classification of plants. He united related species into genera, similar genera into orders, orders into classes. Thus, he developed and proposed a hierarchy of systematic categories. In total, scientists identified 24 classes of plants. To designate the species, K. Linnaeus introduced a double, or binary, Latin nomenclature. The first word means the name of the genus, the second - the name of the species, for example Sturnus vulgaris.

Carl Linnaeus

In different languages, the name of this species is spelled differently: in Russian - common starling, in English - common starling, in German - Gemeiner Star, in French - etourneau sansonnet, etc. Uniform Latin names of species make it possible to understand who they are talking about, facilitate communication between scientists from different countries. In the system of animals, K. Linnaeus identified 6 classes: Mammalia (Mammals). He placed man and apes in the same order Primates (Primates); Aves (Birds); Amphibia (Reptiles, or Amphibians and Reptiles); Pisces (Pisces); Insecta (Insects); Vermes (Worms).

The emergence of a natural system of classification.

The system of K. Linnaeus, despite all its undeniable advantages, was inherently artificial. It was built on the basis of external similarities between various species of plants and animals, and not on the basis of their true relationship. As a result, completely unrelated species fell into the same systematic groups, and close ones turned out to be separated from each other. For example, Linnaeus considered the number of stamens in plant flowers as an important systematic feature. As a result of this approach, artificial plant groups were created. So, viburnum and carrots, bluebells and currants fell into one group only because the flowers of these plants have 5 stamens. Linnaeus, different in the nature of pollination, placed plants in one class of monoecious: spruce, birch, duckweed, nettle, etc. However, despite the shortcomings and errors in the classification system, the works of K. Linnaeus played a huge role in the development of science, allowing scientists to navigate the diversity of living organisms.

Classifying organisms according to external, often according to the most striking signs, K. Linnaeus did not reveal the reasons for such similarities. This was done by the great English naturalist Charles Darwin. In his work "The Origin of Species ..." (1859), he first showed that the similarity between organisms can be the result of a common origin, i.e. kindreds of species.

From that time on, systematics began to carry an evolutionary load, and the classification systems built on this basis are natural. This is the unconditional scientific merit of Charles Darwin. Modern taxonomy is based on the commonality of essential morphological, ecological, behavioral, embryonic, genetic, biochemical, physiological and other features of the classified organisms. Using these features, as well as paleontological information, the taxonomist establishes and proves the common origin (evolutionary relationship) of the species under consideration, or establishes that the classified species are significantly different and distant from each other.

Systematic groups and classification of organisms.

The modern classification system can be represented as the following scheme: empire, super-kingdom, kingdom, sub-kingdom, type (department - for plants), subtype, class, order (order - for plants), family, genus, species. For extensive systematic groups, additional intermediate systematic categories have also been introduced, such as superclass, subclass, superorder, suborder, superfamily, subfamily. For example, the classes of cartilaginous and bony fish are combined into a superclass of fish. In the class of bony fish, subclasses of ray-finned and lobe-finned fish, etc., were distinguished. Previously, all living organisms were divided into two kingdoms - Animals and Plants. Over time, organisms were discovered that could not be attributed to any of them. Currently, all organisms known to science are divided into two empires: Precellular (viruses and phages) and Cellular (all other organisms).

precellular life forms.

In the precellular empire there is only one kingdom - viruses. These are non-cellular life forms capable of penetrating and multiplying in living cells. For the first time, science learned about viruses in 1892, when the Russian microbiologist D.I. Ivanovsky (1864-1920) discovered and described the tobacco mosaic virus, the causative agent of tobacco mosaic disease. Since that time, a special branch of microbiology has emerged - virology. Distinguish between DNA-containing and RNA-containing viruses.

Cellular life forms.

The Cellular Empire is divided into two super-kingdoms (Pre-Nuclear, or Prokaryotes, and Nuclear, or Eukaryotes). Prokaryotes are organisms whose cells do not have a formalized (membrane-limited) nucleus. The prokaryotes include the kingdom of Drobyanok, which includes half the kingdom of Bacteria and Blue-Greens (Cyanobacteria). Eukaryotes are organisms whose cells have a well-formed nucleus. These include the kingdoms of Animals, Fungi, and Plants (Figure 4.1). In general, the Cellular empire consists of four kingdoms: Drobyanki, Fungi, Plants, and Animals. As an example, consider the systematic position of a well-known bird species - the common starling:

Type of systematic category Category name

Empire Cellular

Superrealm Nuclear

Kingdom Animals

Under the realm of Multicellular

Type Chordates

Subtype Vertebrates

Superclass Terrestrial vertebrates

Bird class

Subclass Fan-tailed or true birds

Superorder Typical birds

Order Passeriformes

Starling family

Genus True starling

View Common Starling

Thus, as a result of long-term research, a natural system of all living organisms was created.