Primary consumers

Primary consumers feed on primary producers, that is, they are herbivores. On land, many insects, reptiles, birds and mammals are typical herbivores. The most important groups of herbivorous mammals are rodents and ungulates. The latter include grazing animals such as horses, sheep, cattle, adapted to run on their fingertips.

In aquatic ecosystems (freshwater and marine), herbivorous forms are usually represented by mollusks and small crustaceans. Most of these organisms - cladocerans and copepods, crab larvae, barnacles and bivalves (eg mussels and oysters) - feed by filtering the smallest primary producers from the water. Together with protozoa, many of them make up the bulk of the zooplankton that feed on phytoplankton. Life in the oceans and lakes is almost completely dependent on plankton, since almost all food chains begin with it.

biotic ecosystem sun food trophic

Consumers of the second and third order

Plant material (e.g. nectar) > fly > spider >

> shrew > owl

organic molecules, synthesized by autotrophs, serve as a source of nutrition (substance and energy) for heterotrophic animals. These animals, in turn, are eaten by other animals, and in this way energy is transferred through a series of organisms, where each subsequent one feeds on the previous one. Such a sequence is called a food chain, and each link in the chain corresponds to a certain trophic level (from the Greek troph - food). The first trophic level is always made up of autotrophs, called producers (from Latin producere - to produce). The second level is herbivores (phytophages), which are called consumers (from Latin consumo - “I devour”) of the first order; the third level (for example, predators) - second-order consumers, etc.

Usually in an ecosystem happens 4-5 trophic levels and rarely more than 6. This is partly due to the fact that at each of the levels part of the substance and energy is lost (incomplete eating of food, respiration of consumers, "natural" death of organisms, etc.); such losses are reflected in the figure and are discussed in more detail in the corresponding article. However, according to recent studies, the length of food chains is limited by other factors. It is possible that the availability of preferred food and territorial behavior play a significant role, which reduces the population density of organisms, and, hence, the number of higher-order consumers in a particular habitat. According to existing estimates, up to 80% of primary production in some ecosystems is not consumed by phytophages. Dead plant material becomes prey for organisms that feed on detritus (detritivores) or decomposers (destructors). In this case, we speak of detrital food chains. Detrital food chains dominate, for example, in tropical rainforests.

Producers

Almost all producers- photoautotrophs, i.e. green plants, algae and some prokaryotes, such as cyanobacteria (formerly called blue-green algae). The role of chemoautotrophs on the scale of the biosphere is negligible. Microscopic algae and cyanobacteria that make up phytoplankton are the main producers of aquatic ecosystems. On the contrary, at the first trophic level of terrestrial ecosystems, large plants predominate, for example, trees in forests, grasses in savannahs, steppes, fields, etc.

Energy flow and matter cycling in a typical food chain. Note that between predators and detritivores, as well as decomposers, a bilateral exchange is possible: detritivores feed on dead predators, and predators in some cases eat live detritivores and decomposers. Phytophages are consumers of the first order; carnivorous - consumers of the second, third, etc. orders.

Consumers of the first order

On land, the main phytophages- insects, reptiles, birds and mammals. In fresh and sea water, these are usually small crustaceans (daphnia, sea acorns, crab larvae, etc.) and bivalves; most of them are filterers, straining out producers, as described in the corresponding article. Together with protozoa, many of them are part of zooplankton - a collection of microscopic drifting heterotrophs that feed on phytoplankton. The life of oceans and lakes is almost entirely dependent on planktonic organisms, which are in fact the beginning of all food chains in these ecosystems.

Consumers of the second, third and subsequent orders

Second order consumers they eat phytophages, that is, they are carnivores. Consumers of the third order and consumers of higher orders are also carnivores. These consumers can be divided into several ecological groups:

Here are two examples based on food chain photosynthesis:

Plant (leaves) -> Slug - "Frog -" Already - * - "Emine

Plant (phloem sap) -» Aphid -> Ladybug -> -» Spider -^ Starling -> Hawk

Are you familiar with such concepts as consumers, decomposers and producers? If not, then our article is for you. In fact, these organisms are well known to everyone. Who are they? Let's figure it out together.

The concept of the trophic chain

All components of the ecosystem are closely interconnected. Thanks to this, various communities are formed in nature. The structure of any ecosystem includes abiotic and biotic parts. The first is a collection of living organisms. It is called biocenosis. The abiotic part includes mineral and organic compounds.

The functioning of any ecosystem is associated with the conversion of energy. Its main source is sunlight. Photosynthetic organisms use it to synthesize organic substances. Heterotrophs obtain energy from the breakdown of organic matter. Only a small part of it is used for growth. And the rest is spent on existence of life processes.

As a result, orders are formed in which individuals of one species, their remains, or are a source of food for others. They are called trophic or food chains.

Trophic levels

Each food chain consists of a certain number of links. It has been established that during the transition from one to another, part of the energy is constantly lost. Therefore, the number of links is usually 4-5. The position of a population of individual species in the food chain is called the trophic level.

What are consumers

All organisms are grouped. They include representatives of absolutely all kingdoms of wildlife, regardless of the level of their organization. Let's consider each of them.

Consumers: orders

Heterotrophs occupy different levels in the food chain. All herbivorous species are the next level - it's predators. They are already second order consumers.

Let's consider this hierarchy on a specific example. Let's say the food web looks like: a mosquito, a frog, a stork. Which of them is the consumer of the first order? This is a frog. Then the consumer of the second order is the stork. In nature, there are heterotrophs that feed on both plants and animals. Such consumers can simultaneously be at several trophic levels.

Producers

Speaking about what consumers are, we paid attention to the type of their food. Let us consider another group of the trophic web from this perspective. Producers are a group of organisms that are autotrophs. They are able to synthesize organic substances from minerals.

There are two types of producers: auto- and chemotrophs. The former use the energy of sunlight to create organics. These are plants, cyanobacteria, some protozoa. Chemotrophs have the ability to oxidize various chemical compounds. At the same time, energy is generated, which they use to carry out waste products. These include nitrogen-fixing, sulfur, iron bacteria.

The presence of producers is a necessary condition for the development of any ecosystem. This fact is explained by the fact that photosynthetic organisms are a source of energy.

decomposers

Another role in the ecosystem belongs to heterotrophic organisms that feed on the organic matter of the remains or waste products of other species, which they decompose into minerals. This function is performed by reducers. Representatives of this group are bacteria and fungi.

It is at the level of producers in the ecosystem that energy is accumulated. Then it passes through consumers and producers, where it is consumed. At each subsequent trophic level, part of the energy is dissipated in the form of heat.

Types of food chains

The energy in the ecosystem is divided into two streams. The first is directed to consumers from producers, the second - from dead organic matter. Depending on this, food webs of pasture and detrital types are distinguished. In the first case, the initial trophic level is the producers that transfer energy to consumers of different levels. The pasture chain ends with decomposers.

The detritus chain begins with dead organic matter, and continues with saprotrophs, which are representatives of consumers. The last link in this chain are also decomposers.

Within any ecosystem, there are many trophic chains simultaneously. All of them are inseparable from each other and are closely intertwined. This happens because representatives of the same species can simultaneously be links in different chains. This is how trophic webs are formed. And the more branched they are, the more stable the ecosystem.

Phytophages and carnivores

The structure of the living matter of the ecosystem. Biotic structure. Autotrophs and heterotrophs

Ecosystem. Ecosystem features

Ecosystem homeostasis. ecological successions. Types of natural and anthropogenic successions. The concepts of climax, stability and variability of ecosystems.

populations in an ecosystem.

Producers. Consumers I, II order. Detritophages. Reducers.

Phytophages and carnivores.

The structure of the living matter of the ecosystem. Biotic structure. Autotrophs and heterotrophs.

Ecosystem. Ecosystem features.

Topic 3. Ecosystem. Structure of ecosystems

Bioconsumption. Population size and sustainability of the biosphere

The concepts of noosphere and technosphere

The term "ecosystem" was proposed by the English ecologist A. Tensley in 1935.

Ecosystem is any set of interacting living organisms and environmental conditions.

“Any unit (biosystem) that includes all co-functioning organisms (biotic community) in a given area and interacts with the physical environment in such a way that the flow of energy creates well-defined biotic structures and the circulation of substances between living and non-living parts, is ecological system, or ecosystem"(Yu. Odum, 1986).

Ecosystems are, for example, anthills, a piece of forest, a farm area, a spacecraft cabin, a geographic landscape, or even the entire globe.

Ecologists also use the term "biogeocenosis", proposed by the Russian scientist V.N. Sukachev. This term refers to the totality of plants, animals, microorganisms, soil and atmosphere on a homogeneous land area. Biogeocenosis is one of the ecosystem options.

Between ecosystems, as well as between biogeocenoses, there are usually no clear boundaries, and one ecosystem gradually passes into another. Large ecosystems are made up of smaller ecosystems.

Rice. "Matryoshka" of ecosystems

On fig. the "matryoshka" of ecosystems is shown. The smaller the size of an ecosystem, the more closely the organisms that make up it interact. An organized team of ants lives in an anthill, in which all responsibilities are distributed. There are hunter ants, guards, builders.

The anthill ecosystem is part of the forest biogeocenosis, and the forest biogeocenosis is part of the geographical landscape. The composition of the forest ecosystem is more complex; representatives of many species of animals, plants, fungi, and bacteria live together in the forest. The connections between them are not as close as those of ants in an anthill. Many animals spend only part of their time in the forest ecosystem.

Within the landscape, different biogeocenoses are connected by aboveground and underground movement of water, in which minerals are dissolved. Water with mineral substances moves most intensively within the catchment basin - a reservoir (lake, river) and adjacent slopes, from which aboveground and groundwater flow into this reservoir. The ecosystem of the catchment basin includes several different ecosystems - forest, meadow, arable land. The organisms of all these ecosystems may not have direct relationships and are connected through underground and aboveground water flows that move to the reservoir.

Within the landscape, plant seeds are transferred, animals move. A fox hole or a wolf's lair is located in one biogeocenosis, and these predators hunt in a large area consisting of several biogeocenoses.

Landscapes are combined into physical and geographical regions (for example, the Russian Plain, the West Siberian Lowland), where different biogeocenoses are connected by a common climate, the geological structure of the territory, and the possibility of settling animals and plants. Relationships between organisms, including humans, in the ecosystems of a physical-geographic region and the biosphere are carried out through changes in the gas composition of the atmosphere and the chemical composition of water bodies.

Finally, all the ecosystems of the globe are connected through the atmosphere and the World Ocean, into which the products of the vital activity of organisms enter, and form a single whole - biosphere.

The ecosystem includes:

1) living organisms (their totality can be called a biocenosis or biota of an ecosystem);

2) non-living (abiotic) factors - atmosphere, water, nutrients, light;

3) dead organic matter - detritus.

Of particular importance for the allocation of ecosystems are trophic , i.e. nutritional relationships of organisms that regulate the entire energy of biotic communities and the entire ecosystem as a whole.

First of all, all organisms are divided into two large groups - autotrophs and heterotrophs.

autotrophic organisms use inorganic sources for their existence, thereby creating organic matter from inorganic matter. Such organisms include photosynthetic green plants of land and aquatic environment, blue-green algae, some bacteria due to chemosynthesis, etc.

Since organisms are quite diverse in types and forms of nutrition, they enter into complex trophic interactions with each other, thereby performing the most important ecological functions in biotic communities. Some of them produce products, others consume, and others transform it into an inorganic form. They are called respectively: producers, consumers and decomposers.

Producers- producers of products that all other organisms then feed on - these are terrestrial green plants, microscopic sea and freshwater algae that produce organic substances from inorganic compounds.

Consumers are consumers of organic matter. Among them there are animals that consume only plant foods - herbivores(cow) or eating only the meat of other animals - carnivores(predators), as well as those who use both - “ omnivores"(man, bear).

Reducers (destructors)- restorers. They return substances from dead organisms back to inanimate nature, decomposing organic matter into simple inorganic compounds and elements (for example, into CO 2 , NO 2 and H 2 O). By returning nutrients to the soil or aquatic environment, they complete the biochemical cycle. This is done mainly by bacteria, most other microorganisms and fungi. Functionally, decomposers are the same consumers, so they are often called microconsumers.

A.G. Bannikov (1977) believes that insects also play an important role in the decomposition of dead organic matter and in soil-forming processes.

Microorganisms, bacteria and other more complex forms, depending on the habitat, are divided into aerobic, i.e. living in the presence of oxygen, and anaerobic living in an oxygen-free environment.

All living organisms are divided into two groups according to the method of nutrition:

autotrophs(from Greek. autos- himself and tropho- nutrition);

heterotrophs(from Greek. heteros- another).

Autotrophs use inorganic carbon ( inorganic energy sources) and synthesize organic substances from inorganic ones, these are the producers of the ecosystem. According to the source (used) energy, they, in turn, are also divided into two groups:

Photoautotrophs- solar energy is used for the synthesis of organic substances. These are green plants that have chlorophyll (and other pigments) and absorb sunlight. The process by which it is absorbed is called photosynthesis.

(Chlorophyll is a green pigment that causes the color of plant chloroplasts to be green. With its participation, the process of photosynthesis is carried out.

Choroplasts are green plastids found in plant cells and some bacteria. They are used for photosynthesis.)

Chemoautotrophs- chemical energy is used for the synthesis of organic substances. These are sulfur bacteria and iron bacteria that obtain energy from the oxidation of sulfur and iron compounds (chemosynthesis). Chemoautotrophs play a significant role only in groundwater ecosystems. Their role in terrestrial ecosystems is relatively small.

Heterotrophs they use the carbon of organic substances that are synthesized by producers, and together with these substances they receive energy. Heterotrophs are consumers(from lat. consumo- I consume), consuming organic matter, and decomposers, decomposing it to simple compounds.

Phytophages(herbivores). These include animals that feed on living plants. Phytophages include both small animals such as aphids or grasshoppers and giants such as elephants. Phytophages include almost all agricultural animals: cows, horses, sheep, rabbits. There are phytophages among aquatic organisms, for example, grass carp, eating plants that overgrow irrigation canals. Important phytophage - beaver. It feeds on tree branches, and from the trunks it builds dams that regulate the water regime of the territory.

Zoophages(predators, carnivores). Zoophages are varied. These are small animals that feed on amoebas, worms or crustaceans. And big ones, like a wolf. Predators that feed on smaller predators are called second-order predators. There are predatory plants (dew, pemphigus) that use insects as food.

Symbiotrophs. These are bacteria and fungi that feed on the root secretions of plants. Symbiotrophs are very important for the life of the ecosystem. Threads of fungi that entangle the roots of plants help the absorption of water and minerals. Symbiotrophic bacteria absorb gaseous nitrogen from the atmosphere and bind it into compounds available to plants (ammonia, nitrates). This nitrogen is called biological (in contrast to the nitrogen of mineral fertilizers).

Symbiotrophs also include microorganisms (bacteria, unicellular animals) that live in the digestive tract of phytophagous animals and help them digest food. Animals such as cows, without the help of symbiotrophs, are not able to digest the grass they eat.

Detritophages are organisms that feed on dead organic matter. These are centipedes, earthworms, dung beetles, crayfish, crabs, jackals and many others.

Some organisms use both plants and animals as food, and even detritus, and are euryphages (omnivores) - bear, fox, pig, rat, chicken, crow, cockroaches. Euryphage is also a man.

decomposers- organisms that, by their position in the ecosystem, are close to detritophages, since they also feed on dead organic matter. However, decomposers - bacteria and fungi - break down organic matter to mineral compounds, which return to the soil solution and are again used by plants.

Reducers need time to process corpses. Therefore, in the ecosystem there is always detritus - a supply of dead organic matter. Detritus is leaf litter on the surface of forest soil (remains 2–3 years), the trunk of a fallen tree (remains 5–10 years), soil humus (remains hundreds of years), deposits of organic matter on the bottom of the lake - sapropel - and peat in the swamp ( preserved for thousands of years). The longest lasting detritus are coal and oil.

On fig. the structure of the ecosystem, which is based on plants - photoautotrophs, is shown, and the table shows examples of representatives of different trophic groups for some ecosystems.

Rice. Ecosystem structure

Organic substances created by autotrophs serve as food and a source of energy for heterotrophs: phytophage consumers eat plants, first-order predators eat phytophages, second-order predators eat first-order predators, etc. This sequence of organisms is called food chain, its links are located at different trophic levels (represent different trophic groups).

The trophic level is the location of each link in the food chain. The first trophic level is producers, all the rest are consumers. The second trophic level is herbivorous consumers; the third is carnivorous consumers feeding on herbivorous forms; fourth - consumers consuming other carnivores, etc. therefore, it is possible to divide consumers by levels: consumers of the first, second, third, etc. orders (Fig.).

Rice. Nutritional relationships of organisms in biogeocenosis

Only consumers specializing in a certain type of food are clearly distributed by levels. However, there are species that eat meat and plant foods (humans, bears, etc.), which can be included in food chains at any level.

On fig. five examples of food chains are given.

Rice. Some food chains in ecosystems

The first two food chains represent natural ecosystems - terrestrial and aquatic. In the terrestrial ecosystem, predators such as the fox, wolf, eagles, feeding on mice or ground squirrels, close the chain. In the aquatic ecosystem, solar energy, assimilated mainly by algae, passes to small consumers - daphnia, then to small fish (roach) and, finally, to large predators - pike, catfish, pike perch. In agricultural ecosystems, the food chain can be complete, when farm animals are raised (third example), or shortened, when plants are grown that are directly used by humans as food (fourth example).

The examples given simplify the real picture, since the same plant can be eaten by different herbivores, and they, in turn, become victims of different predators. A leaf of a plant can be eaten by a caterpillar or a slug, a caterpillar can become a victim of a beetle or an insectivorous bird, which can at the same time peck at the beetle itself. The beetle can also become a victim of a spider. Therefore, in real nature, it is not food chains that are formed, but food webs.

When energy passes from one trophic level to another (from plants to phytophages, from phytophages to first-order predators, from first-order predators to second-order predators), about 90% of energy is lost with excrement and breathing costs. In addition, phytophages eat only about 10% of the plant biomass, the rest replenishes the supply of detritus and then it is destroyed by decomposers. Therefore, secondary biological production is 20-50 times less than primary.

Rice. Main types of ecosystems

The food chain has a specific structure. It includes producers, consumers (of the first, second order, etc.) and decomposers. More about consumers will be discussed in the article. In order to thoroughly understand who the consumers of the 1st order, 2nd and beyond are, we first briefly consider the structure of the food chain.

The structure of the food chain

The next link in the chain and, accordingly, the tier of the food pyramid are consumers (of several orders). This is the name of the organisms that the producers consume as food. They will be discussed in detail below.

And finally, decomposers - the final tier of the food pyramid, the last link in the chain - "orderlies" organisms. It is an integral and very important component of the ecosystem. They process and decompose high-molecular organic compounds to inorganic ones, which are then reused by autotrophs. Most of them are organisms of rather small sizes: insects, worms, microorganisms, etc.

Who are the consumers

As mentioned above, consumers are located on the second tier of the food pyramid. These organisms, unlike producers, do not have the ability to photo- and chemosynthesis (the latter is understood as the process of obtaining by archaea and bacteria the energy necessary for the synthesis of organic substances from carbon dioxide). Therefore, they must feed on other organisms - those who have such an ability, or their own kind - other consumers.

Animals - consumers of the 1st order

This link in the food chain includes heterotrophs, which, unlike decomposers, are not capable of decomposing organic substances to inorganic ones. The so-called primary consumers (1st order) are those that are directly fed by the biomass producers themselves, that is, the producers. These are primarily herbivorous animals - the so-called phytophages.

This group includes both giant mammals, such as elephants, and small insects - locusts, aphids, etc. It is not difficult to give examples of consumers of the 1st order. These are almost all animals bred by man in agriculture: cattle, horses, rabbits, sheep.

Of the wild animals, the beaver belongs to the phytophages. As you know, he uses tree trunks to build dams, and eats their branches. Some species of fish, such as grass carp, also belong to herbivores.

Plants are consumers of the first order

Summing up, we can draw the following conclusion: consumers are organisms that feed on plants.

Consumers of the second order and beyond

In turn, consumers of the 3rd order - those who eat consumers of the previous order, that is, larger predators, 4th - those who eat consumers of the third. Above the fourth level, the food pyramid, as a rule, does not exist, since energy losses from the producer to the consumer at the previous levels are quite large. After all, they are inevitable on each of its tiers.

It is also often difficult to draw a clear boundary between consumers of certain orders, and sometimes impossible. After all, some animals are simultaneously consumers of different levels.

Also, many of them are omnivorous, for example, a bear, that is, consumers of the first and second order at the same time. The same applies to a person who is omnivorous, although due to different views, traditions or living conditions, for example, he can eat food only of plant origin.