Dividing animals into groups scheme. What groups of animals are there? Section: Wild animals

Education

There are an infinite number of different animal species on planet Earth. In order to understand them, it is worth studying the classification, which includes types, classes and orders. Species are the last step of division, and that is why their number is so great. It is better to take several basic types of animals, of which there are much fewer. It will be much more convenient to study the species included in them.

Sponges

For a long time, these animals were considered plants. Science has studied their structure quite recently. The sponge phylum includes a wide variety of animal species. Examples of them can be listed for a very long time. Representatives always live in an aquatic environment, but outwardly they differ in a very impressive way. Sponges may look like featureless growths, cakes, twigs or lumps. The glass appearance of these animals looks incredibly beautiful and is a real masterpiece of nature - the so-called Venus basket or sea orange seem openwork and translucent.
They also have common features - for example, their lips hardly move. However, each species is able to obtain food without any problems - by passing impressive volumes of water through the body, microorganisms from which are the diet of these bizarre creatures. But the most interesting thing is that the coincidence of the name of these animals with the name of household utensils for washing or cleaning is not accidental: previously, living sponges were used for these purposes, which are good for the skin and can be very gentle to the touch.

Coelenterates

So, when listing the types of animals, examples should be divided into categories according to their main types. The next one is the coelenterates, low-organized creatures whose bodies consist of only two layers of cells. All of their species, with a few exceptions, live in aquatic environments. For example, this is the hydroid eudendrium, the coral acropora or the siphonophora physophora. Each of these species has a unique appearance - some look like small trees, while others resemble bird feathers. They are united by their habit of living in colonies and the structure of the body - as the name implies, the only body cavity is the intestine. All species can be divided into two groups: these are polyps, located in a certain place, or jellyfish, which can be mobile.

Video on the topic

Worms

When listing animal species, the list of which is very long, it is worth mentioning this type. Worms can be flat, ringed or round. All these species are united by a structure of several layers of cells - ectoderm, endoderm and mesoderm. Worms have no body cavities; the body consists of parenchyma, which performs all the necessary functions. However, there is a difference between these types. Flatworms have a brain stem, roundworms have only a few longitudinal and peripharyngeal nerve rings, and annelids have an abdominal nervous system. In addition, the latter have a closed circulatory system, which others do not have.

Shellfish

It is not only primitive animal species that are worth studying. The classification also includes much more developed organisms, for example, mollusks. This is the type that includes the maximum number of species. These are organisms that live in the sea (oysters, octopuses, mussels, squid), fresh water (toothless, livebearers, pond snails) or in damp soil (snails, slugs). The sizes of mollusks of different species vary greatly; they can be very tiny (just a few millimeters) or reach more than twenty meters in length. Many are sedentary, but some can move in a reactive manner. These are squids and similar species of animals. The classification of mollusks also includes options such as cephalopods, bivalves and gastropods. Some have a shell consisting of several layers (horny and calcareous), but many have lost it during evolution. What unites all these animal species, the names of which, by the way, include snails and squids, is the structure of the digestive system. It consists of three sections with the foregut, middle and hindgut. Some individuals are distinguished by a muscular tongue with teeth, while others feed passively, simply filtering food from the water suspension with their gills. In all species, the circulatory system is not closed and includes blood vessels and a heart with several atria and a ventricle. Aquatic organisms breathe through gills, while terrestrial organisms breathe through lungs. The excretory system is represented by the kidneys, and the nervous system is represented by scattered nodes with several large ganglia.

Arthropods

While listing the various species of animals, the list cannot be completed without mentioning these organisms. Arthropods include centipedes, scorpions, spiders, and crayfish. As a rule, these are bilaterally symmetrical animals with a body divided into segments. The body is covered with a chitin cuticle, which serves as an exoskeleton and protection for the body. Since this category includes a variety of animal species, examples of the respiratory system can be diametrically opposed - these are both lungs and gills. All representatives have an open circulatory system. Body shape can be varied. As a rule, the body consists of several segments: head, chest and abdomen - all these types of animals have them. Examples, however, include some variations: in spiders the head and thorax are combined with the abdomen, while in ticks it is almost impossible to distinguish the segments at all.

Chordata

The most common and famous species of animals, photographs of which everyone has seen, belong to this type. It is the highest and presupposes the presence of a skeletal axis, a neural tube. The phylum includes three main types of organisms: tunicates, vertebrates, and tunicates. The first species of animals, examples of which are much less known than the second, most often live in an aquatic environment and settle in colonies. They have barrel- or pouch-shaped bodies, a ganglion-based nervous system, and underdeveloped sensory organs. Such organisms include the following species: ascidians, appendicularia, pyrosomes and others. These creatures reproduce in different ways, feeding on algae, small animals, and detritus. Interestingly, the adult form is simplified, but the larvae are much more active and have developed sensory organs. Skullless do not have a separate head, which determines their name. They breathe with gills and do not have too many representatives; the most famous is the lancelet. Finally, vertebrates are the most famous and developed group of animals. This includes all species of mammals, fish, birds, amphibians and reptiles. This type developed back in prehistoric times. At the moment, about fifty thousand species of vertebrates are known to man.

Comments

Similar materials

Education
Animal migrations: examples, causes, types. Why do animals migrate?

Do you know why animal migration occurs? 7th grade learns about this in biology lessons. And even then, during their acquaintance with the secrets of biological science, children’s consciousness begins to be accustomed to understanding everyday facts...

Business
Connections: purpose, types of connections. Examples, advantages, disadvantages of types of connections

Machines and machine tools, equipment and household appliances - all these mechanisms have many parts in their design. Their high-quality connection is a guarantee of reliability and safety during operation. What types of connections...

Business
Charity is... Types and examples of charity

It just so happens that in the world there is a fairly clear division of people into poor and rich. This is due to many factors, including employment, economic development of the country and others.About…

Business
Valuation of fixed assets. Types of assessment and classification

In a market economy, each enterprise owns certain property. Without this, the company would not be able to produce goods or provide services. As part of the non-current part of assets, fixed assets are...

Business
Assortment: types of assortment and classification

Products collected in a group, which is formed in accordance with their similarity in one or more characteristics, are called “assortment”.

Business
Main types of lumber, characteristics, classification and scope of application

Today, almost every branch of the national economy uses wood products for various purposes. This is due to the unique properties of this material. Synthetic products are not yet able to replace it. This is…

Business
What is outsourcing in simple words? Outsourcing: Definition, Meaning, Types and Examples

The principle of division of labor is recognized as one of the good ways to increase the efficiency of the work process and achieve greater productivity from personnel. True, not all enterprises can afford to create a large staff of narrow...

Business
Wear. Types of wear and classification

Every person has long known that everything around us tends to wear out. This applies to both buildings and any equipment. Moreover, equipment and real estate items need to be replaced not only when they...

Business
Types of activities of individual entrepreneurs - classification and description

Individual entrepreneurs have rights and civil responsibilities that are necessary to conduct various types of activities, unless they are prohibited by law. Some types of individual entrepreneur activities require a license...

Business
Types of production processes. Classification.

At the heart of any type of industrial activity is the production process. It represents the related stages of transformation of the product of labor (materials, raw materials) into the final product, which is the goal of production….

Linnaeus admitted that within each species of animals and plants very wide differences in a number of characteristics are possible: in growth, fur color, etc. Therefore, for some species it is necessary to allow the existence of so-called “subspecies” or “varieties”.

However, Linnaeus argued that each species is sharply different from other species, even those close to it.

Section: Wild animals

He considered it completely impossible to allow a transition from one species of animal to another. According to Linnaeus, species are permanent, and they exist as long as God created them. According to Linnaeus’ definition, one species of animal or plant should include all those individuals that “resemble each other, like children resemble their parents, and are capable of reproducing by mating with each other.”

As we see, Linnaeus did not want to deviate in any way from the biblical theory of immutability and constancy of species, and therefore he sought to subordinate all his enormous knowledge as a scientist to the requirements of religion. But all his efforts invariably met with a number of difficult to resolve contradictions. Thus, his definition of species did not fit into the fact known to every rural owner that such undoubtedly different types of domestic animals as horses and donkeys are capable of interbreeding with each other and produce mules as offspring. Therefore, Linnaeus and his followers had to introduce an additional definition that offspring from individuals of the same species must necessarily be fertile. From different species, even if it is possible to obtain offspring, they will certainly be sterile (for example, a mule).

Soon, however, it turned out that this additional requirement of Linnaeus did not save the situation, for by now we know dozens of facts that indicate that in many cases, as a result of crossing obviously different, isolated, according to Linnaeus, species of animals and plants, They not only reproduce well, but also produce fertile offspring. Many similar cases are known for various species of wild ducks and geese; similar cases of the birth of fertile offspring can be observed when crossing different species of wild deer. Various types of wild sheep, etc., easily interbreed and produce fertile offspring.

Especially many examples of the fertility of offspring obtained from crossing parents descending from clearly different species are known in the plant world.

If you find an error, please select a piece of text and press Ctrl+Enter.

In contact with

Classmates

Diversity of fauna

We are surrounded by a huge world of living beings - plants, animals, microorganisms - forming various combinations in different parts of our planet. Both the species themselves and their complexes - biocenoses - arose long before the appearance of humans as a biological species. With each era in the history of the Earth, this world changed more and more. The first primitive groups of organisms were replaced by new, morphophysiologically advanced groups that had broader evolutionary potential, and this continues as long as life exists on Earth. All this is the result of organic evolution, which can be called in one word - biodiversity.

Biodiversity includes hundreds of thousands of species, diversity within the populations of each species, and diversity of biocenoses, that is, diversity is observed at every level - from genes to ecosystems. This phenomenon has been of interest to humans for a long time. First, out of simple curiosity, and then quite consciously and often for practical purposes, a person studies his living environment. This process has no end, since with each century new problems arise and ways of understanding the composition and structure of the biosphere change. They are solved by the entire complex of biological sciences.

The study of the diversity of the organic world of our planet has become especially relevant after the role of diversity itself in maintaining the stability of the biosphere began to become clear. Its seemingly unshakable state and its inexhaustible resources turned out to be so disrupted over a short period of time that this began to cause justified concern for humanity. The growing pressure of human economic activity on the biosphere, the direct, although sometimes unconscious, destruction of many species of plants and animals, and changes in the habitat of other species can ultimately lead to catastrophic consequences.

Therefore, the increased interest in studying the role of biodiversity in the stability of the biosphere, from which humans receive resources for their existence, is understandable. Sustainable environmental management is the reasonable use of the gene pool of plants and animals in combination with its long-term conservation; this goal can be achieved only with a clear understanding of the processes occurring in the biosphere, the connections and interdependencies between the components of ecosystems, and, above all, from knowledge of the diversity that surrounds us.

All animals, like other living organisms, are united by scientists into systematic groups based on signs of kinship. The smallest of them is the species. All white hares living in the taiga, mixed forests or tundra belong to one species - the white hare.

Division of animals into groups: types, classes, orders, genera and species

In zoology, a species is a collection of animals that are similar to each other in all essential features of structure and vital activity, live in a certain territory and are capable of producing fertile offspring. Each animal that has unique structural and behavioral features is called an individual. Similar species are grouped into genera, genera into families, and families into orders. Larger systematic groups of animals - classes, types.

The study of the species richness of the animal world of our planet has a long history, but only in 1758 the famous scientist Carl Linnaeus listed all the animals known at that time, giving them their own Latin names. Over the more than two centuries that have passed since the publication of the tenth edition of Linnaean's System of Nature, our knowledge of the animal world of the Earth has increased immeasurably and continues to increase at a rapid pace. Although the process of studying the faunas of various parts of the globe is far from complete, the results of this study can already be presented.

In the literature one can also find forecast data on the number of animal species in the world. Thus, many believe that after the completion of work on studying the species composition of insects, there will be more than 1.5 million species. The same applies to roundworms and some other classes of animals. But even so, their species richness is literally stunning. As you might expect, the number of animal species in different parts of the globe varies. From the lowland areas of the tropical zone to the high latitudes and high altitudes of the mountain ranges, a decrease in diversity is clearly evident. This phenomenon is called the main diversity gradient. As a rule, this concerns not only the general diversity of the animal world, but also the number of species of specific taxa - orders, families, genera - in the faunas of the tropical and temperate zones of the Earth.

We are used to talking about the luxurious nature of the tropics and its poverty in the north. But it's not that simple. Many theories or hypotheses have been proposed to explain the phenomenon of biological diversity. If biological diversity is generally the result of evolution, then why did evolution occur at such different rates in the tropics and the Arctic Circle, on the plains and in the highlands, in the shallows and in the deep trenches of the oceans? Many attempts have been made to elucidate the causal relationships between biodiversity and environmental factors.

Factors influencing biodiversity

Depending on how environmental factors act on organisms - through the physical environment alone, through the physical and biotic environment, or through only the biotic environment, these factors or mechanisms are divided into primary, secondary and tertiary. Of course, the mechanisms themselves are not independent and act in concert and consistently. For some organisms, some factors are more important, for others - others. Let us briefly consider the hypotheses explaining biological diversity.

It has long been believed that the diversity of the animal world increases with the age of the communities in which species live. That is, the first in a series of reasons acting on diversity is called evolutionary time. In temperate zones, especially in the northern hemisphere, habitats are poor in species, since due to the Quaternary glaciation and other geological disturbances, animal species had too little time to adapt and fully develop their habitat. In the tropics, communities are highly diverse because they have not experienced external influences for a long time and evolution has proceeded unhindered, which has led to species richness. This hypothesis is also similar to another one, which takes into account the time required for the dispersal of species, but not for speciation, that is, a shorter ecological time. The following example gives us some idea of ​​this. If we are dealing with a recently emerged area such as a forest burnt area, then its species composition is poor because there simply was not enough time to colonize it with species from neighboring habitats. A classic example of this kind is the history of the settlement of animals on the island of Krakatoa after a catastrophic volcanic eruption that destroyed all life on the island in 1883. It took only 50 years for the formation of a new fauna, but this fauna turned out to be much poorer than the previous one, despite the fact that the island is located in the tropical zone and the distances to the nearest islands are very small.

The most common of all hypotheses is considered to be the one that connects species richness with climate stability, that is, with its slight fluctuations over the seasons. This is exactly what the climate of the tropics is like, especially the equatorial zone. An environment with a stable climate favors specialized species that occupy narrow ecological niches. Let us recall that an ecological niche is a reflection of the place occupied by an organism or species in a community, and this concept includes, in addition to resistance to physical environmental factors, also interactions with other organisms. This means that more species can fit into one area without competing for available resources. We add that in areas with a stable climate, the primary (plant) production of ecosystems is also stable and large, which ensures the coexistence of a larger number of species than in areas with unstable productivity.

The complexity of habitat structure is also important. For many groups of animals, in particular for birds, spatial heterogeneity plays a primary role. This can be seen from the fact that more species of birds live in the forest (multi-tiered structure) than in the meadow. Marine animals living in the intertidal zone, where the bottom consists of particles of various sizes, have more species of invertebrate animals than in the same shallow water with a uniform muddy bottom. Thus, there is a correlation between the structural complexity of the habitat and the species diversity of the fauna.

Species diversity can be determined by habitat productivity. In more productive habitats, food is more abundant and varied, so there is also more opportunity for consumer specialization than in less productive habitats. Many ecologists assign an important role in the formation of species-rich communities to such a biotic mechanism as competition. Charles Darwin pointed out the role of competition as a driving force in the process of speciation. Competition leads to divergence in ecological niches, and specialized species have narrow niches, allowing for high diversity. Particularly intense interspecific competition is observed in communities such as tropical rain forests. They are distinguished by the highest biological diversity and small sizes of species populations. It is known that 1 hectare of such forest can grow from 50 to 100 species of trees. High plant diversity, in turn, favors the development of animal diversity, especially birds and insects, while many species are rare and the number of individuals of any one species is small.

Finally, biodiversity researchers attribute an important place among its mechanisms to predation. This mechanism is that predators feed on prey that is most abundant in a given area, that is, the most common, so-called background species. In this case, predators act as a rarefaction factor. Therefore, they make local coexistence of species possible, weakening competition between them and leading to an increase in various prey.

In all likelihood, none of the environmental factors, taken separately, is able to explain the reason for the diversity of species in a particular landscape zone of the globe. Recently, a special discussion of the correlation between climate and diversity was devoted to work based on a comparison of the number of species of certain groups of insects on the territory of the Russian Plain. The authors came to the conclusion that the problem of the relationship between climate and biodiversity is still at the descriptive stage of study. In addition, they believe that the evidence base to link the response of biota to global warming is still insufficient. The last statement is important in the sense that it calls into question the statements of many ecologists who talk about the global consequences of global warming caused by human activity.

The studies on the basis of which certain hypotheses were proposed were carried out on various groups of animals with different requirements for the environment. As a result, the conclusions of the authors often do not coincide. Different groups of organisms have different correlations of diversity with vegetation structure, environmental stability, moisture conditions, etc. Therefore, diversity is the result of contradictions, a compromise between the genetically inherent potential of morphogenesis and environmental resources. In a general sense, we can say that evolution is directed towards increasing diversity. The evolution of diversity is a self-propelling process; it creates the prerequisites for the further evolution of diversity, therefore it can be argued that diversity generates diversity according to the feedback principle.

How many species of animals inhabit the Earth?

One million, ten million, fifty? We don't know. Over a million living creatures have been scientifically described, named and cataloged. This includes almost all large, visible and accessible representatives of the fauna - birds, mammals and reptiles.

Judging by the number of “new” insects discovered annually, we know only a small part of their total number. In some collections collected under the canopy of tropical jungles, about 90% of insect species were previously unknown to science. Therefore, according to estimates by a number of scientists, there can be up to 50 million species of insects alone, plus a countless army of mollusks, worms, crustaceans and similar small living creatures.

Compared to this wealth, 40 thousand species of vertebrates - fish, amphibians, reptiles, birds and mammals, including you and me - constitute a more than modest part of the animal world. This is clearly seen in the systematization of animals into groups with similar characteristics, each of which is called a phylum. There are 32 types of animals in total, and vertebrates make up only a small part of one of them. All other types cover a bewildering variety of living creatures, from plant-like sponges to intelligent octopuses. We know many of them by name at best.

Using new collection methods or exploring previously neglected sites can also produce a sudden surge in the number of new species. The interstitial fauna of sea coasts (animals living among grains of sand in the intertidal zone) has turned out to be such a “gold mine” in recent decades. Not so long ago, completely unexpected discoveries were accidentally made, which turned out to be, at least for zoologists, sensational. We are, of course, not talking about Bigfoot or sea monsters. In 1938, a coelacanth was caught - the first living representative of the lobe-finned fish, from which amphibians originated, which were considered extinct about 70 million years ago. Extinct even earlier; in the Devonian, they also considered the class of mollusks Monoplacophora, interesting because imprints of places to which muscles were attached were found on their shells. This indicates an elementary segmentation of their body and, according to some scientists, indicates a connection between the mollusks and annelids. And since 1952, we have known these animals not only in the form of fossils. They still live today! Representatives of the genera Neopilina and Vema were found in the Pacific Ocean at a depth of several thousand meters. True, the supposed relationship with annelids has not yet been confirmed.

Somewhat later, another sensation: for the first time, gastropods with a bivalve shell were found. It was tempting to see them as a link between gastropods and bivalves. But this assumption was not confirmed either. Meanwhile, two more species of these unusual snails were discovered. They were found not in the inaccessible depths of the sea, but in shallow waters - off the coast of Japan and Australia, in the Gulf of California and off the island of Jamaica. As you can see, the history of zoological discoveries on Earth is not over. Mammal researchers can also hope for luck - just recently, in 1938, a new species of whale, the Tasmanian beaked whale, was described. Then the sea unexpectedly washed several animals ashore. Yet in small and already well-studied groups, such discoveries are very rare.

In the classes of birds and mammals, the number of species even decreased. This happened not so much due to extinction, but due to the fact that over time, scientists abandoned too fractional divisions and many species were united. Thus, the total number of known and as yet unknown species of animals is, apparently, two, or even three million. Incredible variety! But this is only a small fraction of the species that arose and disappeared in the process of evolution. Some once-dominant groups of animals, once so numerous that scientists use their fossil remains to determine the age of geological strata, have become completely extinct. Of others, which also reached significant prosperity in the past, for example, brachiopods, only pitiful crumbs have survived. But even in such ancient classes as crustaceans, insects, fish, and even in the relatively young classes of birds and mammals, the number of extinct species is much greater than the number of our “contemporaries.”

The distribution of animals on land, in fresh water bodies and seas is extremely uneven. The sea is the cradle of life; the earliest stages of the evolution of the animal world took place here. Many ancient groups never found their way to land or fresh water. This applies to the cephalopods, echinoderms and tunicates that thrive in the seas to this day, as well as to some small surviving groups and to many extinct branches of the animal kingdom. But, despite the vast expanses of the World Ocean, it would be a gross mistake to conclude that the number of marine species exceeds the number of freshwater or terrestrial ones.

The millions of years that have passed since their appearance, and the relative constancy of environmental conditions, would seem to have allowed marine animals to exist much longer and opened up limitless scope for development. But no! It is precisely due to these circumstances that the number of species in the sea is relatively small: the constancy of conditions over a large area and for a long time contributes to the preservation, rather than fragmentation, of any group of animals. The huge number of species of terrestrial animals is the result of the most diverse conditions of their existence. It is surprising and little understood why the return route to the sea turned out to be inaccessible for insects that have adapted to the most incredible conditions on land. On any coast, except perhaps the coldest, we will find many species of insects, but there are none in the thickness of sea water. True, in the open sea you can find Halobatidae bugs, reminiscent of water striders from our puddles and ponds. They also rush along the surface of the water, but that’s all. Spiders also did not become true sea inhabitants, although some of them settled in coral reefs.

Of course, there are species that differ little in their environmental requirements. However, as a rule, such differences are still expressed quite clearly. The very fact of the existence of many specialized species indicates that animals were able to adapt to almost any food and any climatic conditions within the boundaries determined by the biochemical laws of the body. As a result of this process, which lasted hundreds of millions of years, animals populated the globe from pole to pole. They withstand the snow storms of the long polar night, live in subpolar reservoirs and deep seas at temperatures around 0°C. Life does not stop in hot springs, where the water temperature reaches and sometimes exceeds 50°C. However, in most animals, already at temperatures slightly below 50 ° C, enzymatic systems become disordered and proteins change irreversibly. It seems to us unbearable the heat that the animals of the steppes and deserts, located directly on the surface of the soil, withstand, because it heats up much more than the air. True, many desert inhabitants leave their underground shelters only at night or in the evening.

The animal world is large and diverse. Animals are animals, but adults decided to divide them all into groups according to certain characteristics. 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 tupayas 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.

Types of multicellular animals: sponges, bryozoans, flatworms, roundworms and annelids (worms), coelenterates, arthropods, molluscs, echinoderms and chordates. Chordates are the most progressive type of animals.

Kingdom Animals and their classification (Scheme, Table)

They are united by the presence of a chord - the primary skeletal axis. The most highly developed chordates are grouped into the vertebrate subphylum. Their notochord is transformed into a spine. The rest are called invertebrates.

Types are divided into classes. There are 5 classes of vertebrates in total: fish, amphibians, birds, reptiles (reptiles) and mammals (animals). Mammals are the most highly organized animals of all vertebrates.

Classes can be divided into subclasses. For example, mammals are divided into subclasses: viviparous and oviparous. Subclasses are divided into infraclasses, and then into squads. Each squad is divided into families, families - on childbirth, childbirth - on kinds. Species is the specific name of an animal, for example, a white hare.

The classifications are approximate and change all the time. For example, now lagomorphs have been moved from rodents into an independent order.

In fact, those groups of animals that are studied in elementary school are types and classes of animals, given intermixed.

The first mammals appeared on Earth about 200 million years ago, separating from animal-like reptiles.

Search Lectures

Diversity of the animal world

The living nature that surrounds us in all its diversity is the result of the 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 type is unique and inimitable. For example, there are more than 1.5 million species of animals. However, according to some scientists, there are at least 2 million species in the insect class alone, the vast majority of which are concentrated in the tropical zone. The number of animals in this class is also large - it is expressed in numbers with 12 zeros. And there can be up to 77 million different single-celled planktonic organisms in just 1 m3 of water.

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

A special science - taxonomy - helps to understand all the diversity of the organic world. Just as a good collector classifies the objects he collects according to a certain system, a taxonomist classifies living organisms based on characteristics. Every year, scientists discover, describe and classify new species of plants, animals, bacteria, etc. Therefore, taxonomy as a science is constantly developing. Thus, 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 invertebrate - pogonophora.

Development of taxonomy (creation of artificial classification systems). Attempts to classify organisms were made by scientists back in ancient times. The outstanding ancient Greek scientist Aristotle described over 500 species of animals and created the first classification of animals, dividing all then known animals into the following groups 1: [ Animals without blood: soft-bodied (corresponds to cephalopods); soft-shelled (crustaceans); insects; cranioderms (shell molluscs and echinoderms).

II. Animals with blood: viviparous quadrupeds (corresponding to mammals); birds; oviparous quadrupeds and legless (amphibians and reptiles); viviparous legless animals with pulmonary respiration (cetaceans); Legless, scaly fish that breathe through gills.

By the end of the 17th century. a huge amount of material was accumulated on the diversity of forms of animals and plants, which required the introduction of the concept of species; this was first done in the works of the English scientist John Ray (1627-1705). He defined a species as a group of morphologically similar individuals and attempted to classify plants based on the structure of their vegetative organs. However, the founder of modern taxonomy is rightfully considered the famous Swedish scientist Carl Linnaeus (1707-1778), who in 1735 published his famous work “The System of Nature”. K. Linnaeus took the structure of a flower as the basis for classifying plants. He grouped closely related species into genera, similar genera into orders, and orders into classes. Thus, he developed and proposed a hierarchy of systematic categories. In total, scientists have identified 24 classes of plants. To designate the species, K. Linnaeus introduced double, or binary, Latin nomenclature. The first word means the name of the genus, the second - the species, for example Sturnus vulgaris. In different languages, the name of this species is written differently: in Russian - common starling, in English - common starling, in German - Gemeiner Star, in French - etourneau sansonnet, etc. Common Latin names of species make it possible to understand who we are talking about and facilitate communication between scientists from different countries. In the animal system, K. Linnaeus identified 6 classes: Mammalia (Mammals). He placed man and monkeys in the same order, Primates; Aves (Birds); Amphibia (Reptiles, or Amphibians and Reptiles); Pisces (Pisces); Insecta (Insects); Vermes (Worms).

The emergence of a natural classification system. K. Linnaeus' system, despite all its undeniable advantages, was inherently artificial. It was built on the basis of external similarities between different species of plants and animals, and not on the basis of their true relationship. As a result, completely unrelated species ended up in the same systematic groups, and closely related species found themselves 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 groups of plants were created. Thus, viburnum and carrots, bells and currants fell into one group only because the flowers of these plants have 5 stamens. Linnaeus placed plants different in the nature of pollination into one class of monoecious plants: spruce, birch, duckweed, nettle, etc. However, despite the shortcomings and errors in the classification system, the works of C. Linnaeus played a huge role in the development of science, allowing scientists to navigate the diversity of living organisms.

The modern classification system can be presented in the form of the following scheme: empire, superkingdom, kingdom, subkingdom, type (division - 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 fishes are combined into a superclass of fishes. In the class of bony fishes, subclasses of ray-finned and lobe-finned fish, etc. are distinguished.

Previously, all living organisms were divided into two kingdoms - Animals and Plants. Over time, organisms were discovered that could not be classified as one 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 Pre-Cellular Empire there is only one kingdom - viruses. They are non-cellular life forms that can invade and reproduce in living cells.

Classification

Science first learned about viruses in 1892, when 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. There are DNA-containing and RNA-containing viruses.

Cellular life forms. The Cellular Empire is divided into two superkingdoms (Pre-nuclear, or Prokaryotes, and Nuclear, or Eukaryotes). Prokaryotes are organisms whose cells do not have a formed (membrane-bound) 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 formed nucleus. These include the kingdoms of Animals, Fungi and Plants.

In general, the Cellular Empire consists of four kingdoms: Grinders, Mushrooms, Plants and Animals.

Control questions

1. What is the essence of the idea of ​​the spontaneous generation of life?

2. How did L. Pasteur prove the inconsistency of the theory of spontaneous generation of organisms?

3. Describe the main idea of ​​A.I. Oparin’s theory of chemical evolution.

4. Give a brief description of the main stages of the origin of life on Earth according to the theory of J. Bernal.

5. Which class of modern animals is represented by the largest number of species?

6. What are the main tasks of taxonomy?

7. Why is Carl Linnaeus considered the founder of modern taxonomy?

8. What is the main merit of Charles Darwin in systematics?

9. What is the main difference between prokaryotes and eukaryotes?

©2015-2018 poisk-ru.ru
All rights belong to their authors. This site does not claim authorship, but provides free use.
Copyright Infringement and Personal Data Violation

Variety of animal species

Animals are the most diverse group of organisms on Earth. Currently, there are about 2 million species of animals on the planet. Most of them are insects (butterflies, mosquitoes, beetles, flies...). About 130 thousand species of mollusks are known: snails, slugs, pearl barley, squid. The diversity of fish is much more modest - only 25 thousand species, and of birds - 8,600 species. And there are only about 4 thousand species of mammals.

Note that we are not talking about the total number of animals in general, but about the number of animal species. The absolute number of animals on our planet is expressed by an astronomical number!

Animals vary in size. For example, a giant blue whale's body weight reaches 150 tons (the mass of such a whale's tongue is equal to the mass of a small elephant), and the slipper ciliates can only be detected using a microscope.

Animals in any habitat do not live everywhere, but occupy the most favorable areas for them. They are called habitats (or habitats) of animals. For example, nightingales are found in damp and shaded areas of the forest. Pike in rivers prefer places with slow currents (pools, pools), overgrown near the banks.

Organisms in nature do not live in isolation from each other, but in species.

A species is a collection of similar individuals capable of interbreeding to form fertile offspring. A species consists of many individuals that reproduce, disperse, and maintain unity in the struggle for existence. The distribution area of ​​a species is called its range.

Zoology is the science of animals. People have been using animals in their lives for a long time. By hunting for animals, protecting their homes from predators and poisonous snakes, etc., they acquired knowledge about their appearance, habitat, lifestyle, habits and passed it on from generation to generation. Over time, books about animals appeared, and the science of zoology arose (from the Greek “zo-on” - animal and “logos” - word, doctrine). Her birth dates back to the 3rd century. BC. and is associated with the name of the ancient Greek scientist Aristotle.

Modern zoology is a whole system of animal sciences. Some of them study the structure, development of animals, lifestyle, distribution on Earth; others are specific groups of animals, for example only fish (ichthyology) or only insects (entomology). The knowledge gained by zoological sciences is of great importance for the protection and restoration of the numbers of a number of animals, the fight against plant pests, carriers and pathogens of human and animal diseases, etc.
Classification of animals. All animals, like other living organisms, are united by scientists into systematic groups based on signs of kinship. The smallest of them is the species. All white hares living in the taiga, mixed forests or tundra belong to one species - the white hare. In zoology, a species is a collection of animals that are similar to each other in all essential features of structure and vital activity, live in a certain territory and are capable of producing fertile offspring. Each animal that has unique structural and behavioral features is called an individual. Similar species are grouped into genera, genera into families, and families into orders. Larger systematic groups of animals - classes, types.
The animal kingdom includes two subkingdoms: Unicellular animals and Multicellular animals, which unite more than 20 types and several hundred classes.

The species diversity of a biocenosis is the totality of plant and animal species that form a given biocenosis; represented by all groups of organisms - producers, consumers and decomposers; disruption of any link in the food chain causes disruption of the biocenosis as a whole (for example, deforestation leads to a change in the species composition of insects, birds, and, consequently, animals).

6 main groups of animals, their brief characteristics and photos

Species diversity is the number of species in a given community or area. There are alpha diversity (the number of species in the biotope in question), beta diversity (the number of species in all biotopes in a given area) and gamma diversity.

Any ecosystem is composed of a certain number of species of plants and animals, between which a kind of balance has been established. Each population of individual species is characterized by a certain relationship between the formation of new individuals and the death of old ones. The system as a whole is characterized by the periodic appearance of some species (as a result of divergence or introduction) and the eradication of others.

The equilibrium number of species decreases when the number of new species decreases and when they become extinct. Let's take an example of an island ecosystem. The formation of species in the island system is replaced by the appearance of species from the nearby mainland; if there are few species on the island, then the rate of colonization of the island by new species will decrease, and the emergence of new species will slow down sharply. If all the species characteristic of the mainland are present on the island, there will be no possibility of species appearing from the mainland at all. As species on the island increase, the rate of extinction increases, due to the large number of populations present and the fact that increased competition accelerates the exclusion of any species.

Small populations tend to die out faster than large populations. On large islands the number of species is higher than on small islands and the extinction curve of species on small islands is higher than on large islands. Mainland populations of most species tend to be larger than island populations, and therefore the rate of species extinction on the island is higher than on the mainland. On the mainland, new species appear more often, formed within a certain region and due to the divergence of species in this region, and less due to the arrival of new species from other territories.

The number of species in a region influences the rate of speciation. If the number of species is high, then stabilization is noted in this process due to a decrease in the ecological capabilities of the system for the formation of new species. The role of species loss is similar in marine island systems and continental systems. The equilibrium number of species indicates the same number of outgoing and emerging species. The intensity of species renewal in most cases exceeds the change in their diversity. The longer the period of ecosystem development, the higher the proportion of endemics in it. In addition, limited lake space and limited diversity of conditions constrain divergence processes. That is, in lake systems the number of species relatively quickly approaches a stable level. Taxa that achieve great diversity are quickly replaced by taxa that evolve slowly but have greater ecological potential and, naturally, are more competitive.

SYSTEMATICS OF ANIMALS. TYPES AND CLASSES
In modern classification systems, the animal kingdom (Animalia) is divided into two subkingdoms: parazoans (Parazoa) and true multicellular organisms (Eumetazoa, or Metazoa). There is only one type of parazoa - sponges. They do not have real tissues and organs; most of their cells are totipotent, i.e. capable of changing their form and function; in addition, many of their cells are motile. In earlier systems, protozoa, a group of very diverse single-celled organisms, were considered another subkingdom of animals. However, among the protozoa there are known plant-like (capable of photosynthesis), intermediate (with characteristics of both plants and animals) and animal-like, i.e. receiving organic food from external sources, forms. As a result, in the modern system of the five kingdoms of life, protozoa are no longer classified as part of the animal kingdom, but are considered a sub-kingdom of the protist kingdom (Protista). Type of sponge (Porifera, from Latin porus - time, ferre - to carry). This type includes primitive multicellular animals that lead a sessile lifestyle, attached to solid substrates in water. Approximately 5,000 species are known, most of them marine.

TYPE FLATWORMS CLASS CESTODES. In common parlance, a worm is any legless animal with a long, soft body. The classification divides worms into a number of types. Worm-like animals are at a much higher stage of development than cnidarians and sponges. Their sensory organs, such as eyespots, are located on the head or the front end of the body, i.e. that part of it that is the first to “get acquainted with the environment.” The general organization changes accordingly: in particular, dorsal (dorsal) and ventral (ventral) sides appear, and usually also a tail. Planaria have separate digestive, reproductive, excretory and nervous systems.

Type gastrociliata(Gastrotricha, from Greek gaster - stomach, thrix, trichos - hair). Tiny (0.5-1.5 mm) oblong animals that live at the bottom of fresh or salt water bodies. These free-living worms, similar in appearance to ciliated unicellular organisms, are sometimes classified as nematodes. However, they differ from them in the cilia that cover the flattened ventral surface of the colorless and transparent body. The dorsal side is usually convex and bears spines, bristles or scales. In most species the head is discernible, and the rear end is forked or simply tapers to a point; red light-sensitive spots and sensory palps or tentacles are sometimes present. The digestive system is continuous with a muscular pharynx for swallowing small algae - the main food of these worms. Nervous system with a paired cephalic ganglion and lateral trunks stretching along the entire body. The pseudocoel is filled with internal organs; protonephridia with “flame” cells are used for isolation. Characteristically, the tail contains glandular cells that secrete an adhesive substance with which the animal attaches to various objects. Most of the female's body is occupied by the genitals. The egg is covered with a thick shell with hooks that attach it to solid objects. Development proceeds without larval stages. In freshwater species, only females are known. Forms that live in salt water are hermaphrodites. About 100 species have been described.

Kinorhyncha type(Kinorhyncha, from Greek kineo - to move, rhynchos - snout). Small, almost microscopic marine animals. The head, consisting of two segments, can be retracted into the first two or three segments of the body. There are no cilia, but the body segments bear separate spines, and the head has corollas of them. The body cavity is a pseudocoel, the digestive system is through. The excretory organs are two tubes, each with a “flame” cell. The nervous system is in contact with the epidermis and includes the anterior dorsal ganglion, the peripharyngeal ring and the abdominal trunk with a ganglion in each segment. The musculature is similar to that known in gastrociliates and rotifers, but is segmented in accordance with the segmented structure of the body. Kinorhynchus are dioecious, but males are usually indistinguishable from females in appearance. Genital ducts are present, and fertilization is presumably internal. Approximately 30 species have been described.
Type of priapulid(Priapulida, from the Greek Priapos - Priapus, the god of fertility, usually depicted with a huge penis). Marine worms living in the cold waters of the North Atlantic, Arctic and Antarctic. They are most similar to kinorhynchs, although their relationship is unclear. The body is cylindrical, approx. long. 10 cm, segmented from the surface and covered with cuticle. The eversible proboscis is covered with spines, also scattered throughout the body. At the posterior end there is a gill-like appendage of unknown purpose. The digestive system is continuous. Priapulids burrow into the mud on the ocean floor, where they prey on other small worms. The excretory organs are protonephridia. Nervous system with perioral ring and ventral nerve trunk without ganglia. All nerve fibers pass through the epidermis. Dioecious animals with external fertilization. Only a few species are known.

Type of bryozoan(Ectoprocta, from Greek ektos - outside, proktos - anus). This phylum is also known as Bryozoa. It includes animals that are externally similar to intrapowderycetes, but with a true coelom, i.e. peritoneal lining of the body cavity. Unsegmented organisms with a continuous digestive tract; there are no circulatory, respiratory or excretory systems. The anus is located outside the tentacular ring of the lophophore, which explains the Latin name of the group - "Ectoprocta" ("outer-powdery"). The nervous system consists of one ganglion and the nerves extending from it. The size of individual individuals does not exceed 3 mm, but creeping colonies covering stones, shells, etc. with a thin crust. substrates can occupy an area of ​​more than 1 m2; There are also massive gelatinous colonies, similar to small pumpkins. All bryozoans are hermaphrodites, but sexual reproduction occurs only during a short season. Colonies arise as a result of budding. Freshwater species also form internal buds, protected by a durable shell, the so-called. statoblasts. If the colony dies due to drying out or freezing, the statoblasts survive and give rise to new individuals. Bryozoans live in water, mainly on the dimly lit lower surfaces of various objects. There are two classes.

Class Angiostomata(Phylactolaema, from Greek phylakto - guard, laemos - pharynx). The lophophore is horseshoe-shaped, and the lip (epistome) hangs over the mouth opening. Exclusively freshwater forms that form statoblasts.

Class naked (Gymnolaemata, from Greek gymnos - naked, laemos - pharynx). The lophophore is ring-shaped, there is no epistome. Most species live in the sea and do not form statoblasts.

Type of cycliophora(Cycliophora, from the Greek kyklion - circle, wheel; phoros - carrier). In 1991, tiny (0.3 mm) creatures were discovered on the mouth parts of a lobster caught between Denmark and Sweden, which turned out to be representatives of a previously unknown group. Their description was first published in 1995. The name given to these animals is explained by the presence of a fringed, wheel-shaped mouth. The life cycle of cycliophorans is very complex and unusual; it involves mobile non-feeding sexual forms (females and dwarf males), attached feeding asexual forms and two types of larvae. The so-called Pandora larvae develop in an asexual organism, and another asexual form develops inside it. Apparently, bryozoans should be considered the closest relatives of cycliophorans.
Type of phoronid(Phoronida, from the Greek Phornis - the name of a nymph). Marine animals with a length of 0.5 to 40 cm. They live alone in secreted tubes, which are immersed with the lower end in silt or sand in shallow sea waters. The edge of the lophophore bears a double row of ciliated tentacles that drive food particles into the mouth. The vermiform body is unsegmented; all species are hermaphrodites. Muscles are longitudinal and circular; the digestive canal is curved in a horseshoe shape; body cavity - whole; the circulatory system is closed. The nervous system is located not in the epidermis, but under it. The nephridial excretory organs open into two small openings near the anus. There are no special respiratory organs.

Cuttlefish is a cephalopod that, when in danger, produces a “smoke screen” consisting of a water-soluble brown secretion of the ink gland. This secret is used to produce a paint called sepia. Previously, the farm also used the rudiment of a cuttlefish shell - a calcareous plate located deep in its body, called the “sepia bone”.

Type of sipunculid(Sipunculida, from Latin siphunculus - pipe). Worm-like marine animals that live in burrows covered inside with mucus. The length of the unsegmented body is from 1 to 50 cm; inside is a vast whole. A mouth bordered with tentacles at the end of a reversible proboscis. There is no skeleton, but all other organ systems are well developed. The animals are dioecious, although males and females do not differ in appearance. The gonads are clearly expressed only during the breeding season. Known approx. 250 species.

Type echinoderm (Echinodermata, from Greek echinos - hedgehog, derma - skin). Marine animals with a radially symmetrical, non-segmented body without a head and a flexible internal skeleton (endoskeleton) made of calcareous plates. The digestive tract usually ends in the anus, but in some species it is absent; the circulatory system is located in a well-developed coelom. The nervous system is primitive, with a radial structure. Almost all are dioecious; Fertilization occurs in sea water. The ability to restore (regenerate) lost body parts is well developed. A unique feature of echinoderms is the ambulacral system, which develops from the coelom. It consists of water-filled tubes and is involved in movement, breathing, excretion and nutrition. Lateral branches extend from the radial canals to hundreds of so-called. ambulacral legs on the surface of the body - cylindrical tubes with an extensible ampoule at the base and a suction cup at the free end. By changing the amount of water in the system and contracting the muscles of the legs and ampullae, the animal attaches to the substrate, can crawl and grab food. Echinoderms are of particular interest because many zoologists consider them to be closely related to hemichordates and chordates. They are similar to representatives of these two types in the method of coelom formation, the formation of mesoderm from the lateral protrusions of the primary intestine, and deuterostome, i.e. the transformation of the blastopore (primary mouth) into the anus and the appearance of the oral opening at the other end of the primary intestine. Most modern echinoderms are crawling animals, but they may have evolved from sessile ancestors. Modern species approx. 5000. Class holothuria, sea cucumbers, or sea capsules (Holothuroidea, from the Greek holothurion - aquatic polyp). Marine animals with a cylindrical body similar to a cucumber. The mouth located at its end is surrounded by a corolla of tentacles. The body is soft and leathery to the touch, since the skeleton consists only of microscopic plates. There are no arms or spines, and radial symmetry is manifested only in the equal distances between the five longitudinal rows of legs. There are so-called water lungs formed by branched invagination of the cloaca. They live in shallow waters, where they crawl very slowly along the bottom. Usually dioecious, although males and females are not distinguishable externally. Known approx. 500 species. Class starfish (Asteroidea, from Greek aster - star). The body is flattened and looks like a star from above. Most often it has five rays, or arms, but some forms have up to 50; the arms are connected to a central disk, the diameter of which is approximately half their length. Each arm contains gonads and digestive glands, and on its lower surface are rows of ambulacral legs. The surface of the body is hard and rough, because The skeletal plates can be clearly felt. On the aboral (upper) side of the disc there is a madrepore plate - a sieve-like entrance to the system of ambulacral canals; the oral (oral) side is at the bottom. Most species are dioecious; Fertilization is usually external. In some species, the female bears the young in a special chamber under the central disk. Most are predators. Approximately 2000 species have been described. Class snaketail, or brittle star (Ophiuroidea, from Greek ophis - snake, ura - tail). Similar in appearance to starfish, there are usually five thin and flexible arms attached to a central disk. Each bears four rows of skeletal plates: aboral (upper), oral (oral, i.e. in this case lower) and two lateral. Only the side rows are prickly. Unlike sea stars, brittle stars have a madrepore plate located on the oral surface of the disc, and the ambulacral legs have lost their motor function and serve as organs of touch. The arms of brittle stars break off easily, but quickly regenerate.

Class sea lilies (Crinoidea, from the Greek krinon - lily). This class unites all living sessile echinoderms (subphylum Pelmatozoa). Their movable rays, or arms, surround the superior oral surface of the body; resembling the long petals of a flower, they give the animal a plant-like appearance. An attachment stalk often extends from below, which appears segmented, because skeletal plates form rings in it. This group is very ancient, existing back in the Cambrian, i.e. 570-510 million years ago. Extinct species approx. 5000, and modern ones are less than 700. Class sea urchins (Echinoidea, from the Greek echinos - hedgehog). The body is usually hemispherical or disc-shaped, protected by a solid shell (“shell”) of skeletal plates welded together and covered with movable needles, firmly attached to the shell with their bases. The mouth contains five strong teeth that make up the chewing apparatus (Aristotle's lantern). All animals are dioecious; have 4-5 gonads; external fertilization. Sometimes, especially in cold seas, the juveniles develop in special pouches on the female’s body. Approximately 2000 species are known. Type hemichordate(Hemichordata, from Greek hemi - half, chorde - string). Worm-like soft-bodied animals that live at the bottom of the sea. The length of some species reaches 2 m. The body consists of a proboscis, a short collar and an elongated torso. Paired gill slits on the anterior part of the latter and the dorsal nerve trunk indicate proximity to chordates, but there is no third main characteristic of them - the notochord. The similarity of the larvae covered with cilia - tornaria in hemichordates and bipinnaria in echinoderms - allows us to consider hemichordates as an intermediate link between echinoderms and chordates. There are two classes, including approx. 100 species. The class is enteric-breathing (Enteropneusta, from the Greek enteron - intestine, pneuma - breath). Mobile bottom animals. Dioecious, but one species is also capable of asexual reproduction by transverse division of the body. Class pterobranchia (Pterobranchia, from Greek pteron - wing, branchia - gills). Sessile, usually colonial forms. Arms with numerous small tentacles extend from the collar.
Type chordates(Chordata, from Greek chorde - string). These secondary cavities are characterized by three main features: 1) a dorsal nerve trunk in the form of a tube; 2) chord, which serves as the axial internal skeleton (endoskeleton); 3) the presence of gill slits at least in the early life stage. The fourth important sign is the heart located on the ventral side of the body. There are three (sometimes four) subtypes. Subtype larval chordates, or tunicates (Urochordata, from Greek ura - tail, chorde - string), or Tunicata (from Latin tunica - shirt-type clothing). Marine animals with a diameter from 1 mm to 40 cm; single or colonial. Some species and all larval stages are free-swimming, but sessile forms are also known. All of them have a body covered with a thick transparent gelatinous membrane - a tunic. Hermaphrodites; Reproduction is sexual or asexual, by budding. There are three classes. Appendicular class (Appendicularia, from Latin appendicula - appendage). Free-swimming forms, from 0.3 to 8 cm long, retaining a tail in adulthood; hermaphrodites, reproduction is only sexual; development is direct (no larval stage). Also called Larvacea. Class ascidia (Ascidiacea, from the Greek askidion - pouch). Solitary and colonial sessile in adult form; in the latter case - with a common tunic. Reproduction is both sexual and asexual - by external budding or the formation of gemmules (internal buds).

Class pelagic tunicates (Thaliacea, from Greek thaleia - flowering). Free-floating forms. The barrel-shaped body is surrounded by circular muscles; contracting, they push the water entering the body from its rear end, providing forward movement. They reproduce both sexually and by budding, in which one adult animal sometimes forms a chain of developing individuals trailing behind it. Subtype cephalochordates (Cephalochordata, from Greek kefale - head, chorde - string). Representatives of this genus - lancelets - live in the sand in the shallow waters of warm seas. The body is lanceolate with one dorsal and two fin folds located on the sides of the ventral side; tail - behind the anus. Body length up to 10 cm. Dioecious creatures.

Subtype vertebrates (Vertebrata, from Latin vertere - to twirl). Vertebrates differ from other chordates in two ways: 1) in most, the notochord is replaced by a segmented (jointed) bone structure called the spine; 2) the brain is protected by a bony cranium, which is why vertebrates are often called craniata (Craniata), in contrast to tunicates and cephalochordates. These are, as a rule, large dioecious animals. They are divided into 7 classes. Class cyclostomata (Cyclostomata, from Greek kyklos - circle, stoma - mouth). These animals, which include hagfishes and lampreys, are the most primitive vertebrates. They are closely related to the scutes (Ostracodermi) of the Devonian period (408-362 million years ago), sometimes called the Age of Fishes; These two groups are combined into the superclass of jawless (Agnatha), opposing all other vertebrates - gnathostomes (Gnathostomata). Cyclostomes have neither jaws nor paired fins. The mouth is in the form of a funnel-shaped sucker with horny teeth for scraping the soft tissues of the animals on which they feed. The body is soft, cylindrical, without scales, covered with mucus; On top of the head there is an unpaired (median) nostril. The heart is two-chambered; cranial nerves 8-10 pairs; the notochord persists throughout life.

Class cartilaginous fish (Chondrichthyes, from the Greek chondros - cartilage, ichthys - fish). Usually these are marine predators - sharks, rays and chimeras. The length of some species reaches 15 m. The skeleton is cartilaginous. The notochord persists throughout life. As a rule, a caudal and paired ventral and pectoral fins are present. The mouth is almost always located on the ventral side. It is armed with jaws with teeth covered with enamel; gill slits 5-7 pairs, heart two-chambered; cranial nerves 10 pairs; two nostrils in front of the mouth; in the lumen of the intestine along its entire length stretches the so-called. spiral valve - a fold that increases the suction area. Tooth-like (placoid) scales make the skin rough. Cartilaginous fishes are possibly closely related to the extinct armored fishes (Placodermi). Sharks and rays are classified into a subclass of elasmobranchs (Elasmobranchii), contrasted with whole-headed ones (Holocephali), i.e. chimeras. Class of bony fish (Osteichthyes, from Greek osteon - bone, ichthys - fish). The skeleton is usually bony; most species have thin, flattened scales. The mouth is usually at the anterior end of the body, with well-developed jaws and teeth. The heart is two-chambered. The gills are attached to the gill arches in the lateral gill cavities, covered by a hard operculum. Most species have a swim bladder. There are 10 pairs of cranial nerves. The sizes are very diverse - from 1 cm to 7 m. This class includes trout, catfish, perch and most other fish inhabiting the planet’s water bodies. Approximately 25,000 species are known. Class amphibians, or amphibians (Amphibia, from the Greek amphi - double, bios - life). Amphibians, which include frogs, toads, salamanders and caecilians, were the first vertebrates with four legs for movement on land (sometimes the legs were lost a second time), and the first to have true lungs that allowed them to breathe air. These are cold-blooded (ectothermic) forms, i.e. their body temperature depends on environmental conditions (like all animals except birds and mammals). The skin is bare, more or less moist, involved in respiration. The heart is three-chambered, consisting of two atria and a ventricle; cranial nerves 10 pairs. With very few exceptions, they are oviparous, with larvae developing in water, and therefore live, as a rule, in damp places near bodies of water. Class reptiles, or reptiles (Reptilia, from Latin repere - to crawl). These animals include (in order of complexity of organization) turtles, lizards, snakes and crocodiles. They were the first to fully adapt to life on land: in addition to legs and lungs, they are characterized by: internal fertilization; eggs protected from drying out by a calcareous or leathery shell; dry skin covered with horny scales. There are 12 pairs of cranial nerves. The heart is usually three-chambered (but with a ventricle separated by an incomplete septum), but in crocodiles it is four-chambered, with two atria and two ventricles. During development, special embryonic membranes are formed: amnion, chorion and allantois, therefore reptiles are classified as amniotes, in contrast to the vertebrates discussed above, called anamnias. Modern reptiles are much inferior in size and diversity to their relatives who lived in the Mesozoic era (from 245 to 65 million years ago), which is called the Age of Reptiles. Bird class (Aves, from Latin avis - bird). These animals differ from all others by the presence of feathers. They are warm-blooded (endothermic), i.e. body temperature is almost constant regardless of environmental conditions. The front pair of limbs are transformed into wings, although in some species the ability to fly is secondarily lost. Bones are light and usually hollow. There are no teeth, although fossil forms had them. In adult birds, only the right aortic arch is preserved; four-chambered heart; The respiratory organs are the lungs, connected to air sacs located throughout the body. There are 12 pairs of cranial nerves. Fertilization is internal, but there is usually no copulatory organ; all are oviparous. The embryonic membranes are the same as those of reptiles (amniotes); lime eggshell. The sizes are very different - from hummingbirds weighing approx. 3 g to ostriches weighing 130-140 kg. Many species are domesticated, and poultry farming constitutes an important branch of agricultural production. Class mammals, or animals (Mammalia, from Latin mamma - female breast). The characteristic features of these animals are hair (coat) and mammary glands, which serve to feed the offspring. The four limbs are differently specialized depending on the function they perform. Most species have auricles and teeth differentiated into several groups. The respiratory organs are only the lungs, the ventilation of which is facilitated by the diaphragm (the muscular partition between the chest and abdominal cavities). All species are warm-blooded. The heart is a four-chambered heart; In the adult body, only the left aortic arch is preserved. There are 12 pairs of cranial nerves. Fertilization is internal, using the copulatory organ (penis). The embryonic membranes are characteristic of amniotes, and the yolk sac is usually vestigial, because The vast majority of species (except for monotremes - the platypus, echidna and proechidna) are viviparous. Mammals vary greatly in size: from shrews weighing 1.5 g, to whales over 30 m long and weighing up to 120 tons. The number of modern species is 4000.
Collier's Encyclopedia

Section of systematics (See Taxonomy). The animal system was first developed in the 4th century. BC e. Aristotle, who described more than 450 forms, dividing them into 2 large groups of animals supplied with blood (vertebrates, according to modern... ...

- (from the Greek systematikos, ordered, relating to a system) area of ​​knowledge within which the tasks of designating and describing the entire set of objects that form a certain sphere of reality are solved in a certain way.… … Great Soviet Encyclopedia

SYSTEMATICS- SYSTEMATICS, a science that studies organisms from the point of view of their similarities and differences and strives to build a natural system, that is, to distribute all organisms based on the totality of their signs of similarity and difference into groups of varying sizes,... ... Great Medical Encyclopedia - Contents 1 Goals and principles of taxonomy 2 History of taxonomy ... Wikipedia

Animals Clockwise from top left: European squid (mollusks), sea nettles (cinidras), leaf beetles (arthropods), nereids (annelids) and tiger (chordates) ... Wikipedia

Also called comparative morphology, it is the study of the patterns of structure and development of organs by comparing different types of living things. Data from comparative anatomy are the traditional basis of biological classification. Under morphology... Collier's Encyclopedia

This page is proposed to be merged with Parazoi. Explanation of reasons and discussion on the Wikipedia page: Toward unification / October 30, 2011. The discussion lasts one week (or longer if it goes ... Wikipedia

In order not to get confused in all the diversity of animals that live and have lived on Earth, it is necessary to divide them into interconnected groups. In other words, animals need to be classified. Science deals with the classification of all living organisms and animals in particular. taxonomy of the living world.

Despite the fact that the living nature of the Earth has already been well studied by man, new previously unknown species of animals continue to be discovered. Scientists and researchers describe a new species and then, in accordance with the classification of animals, assign it to one group or another.

The main thing in the classification of animals is the concept of species. In biology view is a collection of individuals that have a similar structure and lifestyle, and when crossed with each other, are capable of producing fertile offspring. Examples of species: domestic cat, homo sapiens, house sparrow, whale shark.

Close species are grouped into genera, close genera into families, families into orders, orders into classes, classes into types. Types make up the kingdom Animalia. At the same time, intermediate groups are often distinguished: subkingdoms, subtypes, subclasses, etc.

Throughout human history, people in different countries have discovered and described animal species. They gave them names. Often the same species was called differently in different places. In order to prevent ambiguity in the classification of living organisms, in the 18th century C. Linnaeus introduced into science the so-called binary nomenclature. This is a way of giving species names consisting of two Latin words. The first word denotes the genus to which the given species of animal belongs, and the second word specifies the species. For example, the red kangaroo is called Macropus rufus in Latin. Here the word Macropus is the Latin name of the genus of gigantic kangaroos, and the word rufus in combination with the first word unambiguously classifies the species.

Animal classification is designed to reflect the evolutionary and related relationships between groups of animals. Single-celled animals are grouped into the subkingdom Protozoa (although nowadays they are usually separated into a separate kingdom). In this subkingdom, the following types are distinguished: Ciliates, Sarcodidae, etc. Multicellular animals are classified as a separate subkingdom. Here the types are Coelenterates, Flatworms, Roundworms, Annelids, Molluscs, Arthropods, and Chordata.

In the phylum of chordates, the classes Cartilaginous fish and Bony fish, Amphibians, Reptiles, Birds and Mammals are distinguished.

The evolution of the animal world on Earth went from unicellular forms to multicellular ones, which subsequently developed complex organ systems (a skeleton, nervous system, etc. appeared). Birds and mammals have the most complex structure.

Groups of animals are not equal to each other in terms of the number of species and their role in nature. Therefore, in the study of zoology, it is common to consider individual classes of one type in more detail, while another type is considered in general. For example, the type of Ciliates is considered in detail, but not the individual classes of this type. While the classes belonging to the phylum Chordata are considered separately.

The animal world is large and diverse. Animals are animals, but adults decided to divide them all into groups according to certain characteristics. 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 tupayas 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.

Types of multicellular animals: sponges, bryozoans, flatworms, roundworms and annelids (worms), coelenterates, arthropods, molluscs, echinoderms and chordates. Chordates are the most progressive type of animals. They are united by the presence of a chord - the primary skeletal axis. The most highly developed chordates are grouped into the vertebrate subphylum. Their notochord is transformed into a spine. The rest are called invertebrates.

Types are divided into classes. There are 5 classes of vertebrates in total: fish, amphibians, birds, reptiles (reptiles) and mammals (animals). Mammals are the most highly organized animals of all vertebrates.

Classes can be divided into subclasses. For example, mammals are divided into subclasses: viviparous and oviparous. Subclasses are divided into infraclasses, and then into squads. Each squad is divided into families, families - on childbirth, childbirth - on kinds. Species is the specific name of an animal, for example, a white hare.

The classifications are approximate and change all the time. For example, now lagomorphs have been moved from rodents into an independent order.

In fact, those groups of animals that are studied in elementary school are types and classes of animals, given intermixed.

The first mammals appeared on Earth about 200 million years ago, separating from animal-like reptiles.

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.

TOP 4 articleswho are reading along with this

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.

Test on the topic

Evaluation of the report

Average rating: 4.4. Total ratings received: 198.