For me, nature is a kind of well-oiled machine, in which every detail is provided. It’s amazing how well everything is thought out, and it’s unlikely that a person will ever be able to create something like this.

What does the term "power chain" mean?

According to the scientific definition, this concept includes the transfer of energy through a number of organisms, where the producers are the first link. This group includes plants that absorb inorganic substances from which they synthesize nutritious organic compounds. They feed on consumers - organisms that are not capable of independent synthesis, which means they are forced to eat ready-made organic matter. These are herbivores and insects that act as “lunch” for other consumers - predators. As a rule, the chain contains about 4-6 levels, where the closing link is represented by decomposers - organisms that decompose organic matter. In principle, there can be much more links, but there is a natural “limiter”: on average, each link receives little energy from the previous one - up to 10%.

Examples of food chains in a forest community

Forests have their own characteristics, depending on their type. Coniferous forests are not distinguished by rich herbaceous vegetation, which means that the food chain will have a certain set of animals. For example, a deer enjoys eating elderberry, but it itself becomes prey for a bear or lynx. The broad-leaved forest will have its own set. For example:

• bark - bark beetles - tit - falcon;
• fly - reptile - ferret - fox;
• seeds and fruits - squirrel - owl;
• plant - beetle - frog - snake - hawk.

It is worth mentioning scavengers who “recycle” organic remains. There are a great variety of them in forests: from the simplest single-celled ones to vertebrates. Their contribution to nature is enormous, since otherwise the planet would be covered with animal remains. They transform dead bodies into inorganic compounds that plants need, and everything starts anew. In general, nature is perfection itself!

They are called trophic levels.

• The first link of the food chain is represented by autotrophic plants (producers). Through the process of photosynthesis, they convert solar energy into the energy of chemical bonds. Chemosynthetic organisms can also be classified as producers.
• The second link is formed by herbivores (primary consumers) and carnivores (secondary consumers) animals, or consumers. The second link is considered heterotrophic organisms.
• The third link in the food chain consists of microorganisms that break down organic matter into minerals (decomposers). The third link is also heterotrophic organisms.

Food chains in nature are usually formed from three to four levels. When moving from one level to another, the amount of energy and biomass decreases approximately tenfold, since 90% of the energy received is spent on ensuring the life of organisms and only 10% on building the body of organisms. Therefore, at each subsequent level, the number of individuals also progressively decreases. For example, if an animal eats 1000 kg of plants, then its weight will increase by an average of 100 kg. The biomass of a predator that eats a herbivore of this mass can increase by 10 kg, while the biomass of a secondary predator can increase by only 1 kg.

Ecological pyramid(Fig. 68) is a graphical display of the ratio of the number of organisms, biomass and energy of producers, consumers and decomposers at the trophic levels of the food chain. It is built according to the so-called ecological pyramid rule- patterns in which a progressive decrease in matter and energy is observed at nutritional levels.

The base of the pyramid is formed by autotrophic organisms - producers, herbivores are located higher, predators are located even higher, and at the top of the pyramid there are large predators. Material from the site

A typical example of food chains in water basins: phytoplankton - zooplankton - small fish - large predatory fish. In this chain, the amount of biomass and energy also decreases according to the rule of the ecological pyramid.

In artificial agricultural ecosystems, there is also a decrease in the amount of energy up to 10 times at each subsequent level of food chains.

Pictures (photos, drawings)

On this page there is material on the following topics:

In living nature there are practically no living organisms that do not eat other creatures or are not food for someone. Thus, many insects feed on plants. The insects themselves are prey for larger creatures. Certain organisms are the links from which the food chain is formed. Examples of such “dependence” can be found everywhere. Moreover, in any such structure there is a first initial level. As a rule, these are green plants. What are some examples of food? What organisms can be links? How does the interaction between them occur? More on this later in the article.

general information

The food chain, examples of which will be given below, is a certain set of microorganisms, fungi, plants, animals. Each link is at its own level. This “dependence” is built on the principle “food - consumer”. At the top of many food chains is man. The higher the population density in a particular country, the fewer links will be contained in the natural sequence, since people are forced in such conditions to eat plants more often.

Number of levels

How does interaction occur within ecological pyramids?

How does the food chain work? The examples given above show that each subsequent link should be at a higher level of development than the previous one. As already mentioned, relationships in any ecological pyramid are built on the “food-consumer” principle. Due to the consumption of some organisms by others, energy is transferred from lower to higher levels. The result occurs in nature.

Food chain. Examples

Conventionally, several types of ecological pyramids can be distinguished. There is, in particular, a grazing food chain. Examples that can be seen in nature are sequences where the transfer of energy occurs from lower (protozoan) organisms to higher (predator) organisms. Such pyramids, in particular, include the following sequences: “caterpillars-mice-vipers-hedgehogs-foxes”, “rodents-predators”. The other, detrital food chain, examples of which will be given below, is a sequence in which the biomass is not consumed by predators, but a process of decay with the participation of microorganisms takes place. It is believed that this ecological pyramid begins with plants. This is, in particular, what the forest food chain looks like. Examples include the following: “fallen leaves—rotting with the participation of microorganisms,” “dead (carnivorous)—predators—centipedes—bacteria.”

Producers and consumers

In a large body of water (ocean, sea), planktonic organisms are food for Cladocera (animal filter feeders). They, in turn, are prey for predatory mosquito larvae. A certain type of fish feeds on these organisms. They are eaten by larger predatory individuals. This ecological pyramid is an example of a sea food chain. All organisms acting as links are at different trophic levels. At the first stage there are producers, at the next - consumers of the first order (consumers). The third trophic level includes 2nd order consumers (primary carnivores). They, in turn, serve as food for secondary predators - third-order consumers, and so on. As a rule, ecological pyramids of land include three to five links.

open water

Beyond the shelf sea, in the place where the slope of the continent breaks off more or less abruptly towards the deep-sea plain, the open sea begins. This area has predominantly blue and clear water. This is due to the absence of inorganic suspended compounds and a smaller volume of microscopic planktonic plants and animals (phyto- and zooplankton). In some areas, the surface of the water has a particularly bright blue color. For example, in such cases they talk about so-called ocean deserts. In these zones, even at a depth of thousands of meters, sensitive equipment can detect traces of light (in the blue-green spectrum). The open sea is characterized by the complete absence of various larvae of benthic organisms (echinoderms, mollusks, crustaceans) in the composition of zooplankton, the number of which sharply decreases with distance from the coast. Both in shallow water and in wide open spaces, sunlight is the only source of energy. As a result of photosynthesis, phytoplankton uses chlorophyll to form organic compounds from carbon dioxide and water. This is how the so-called primary products are formed.

Links in the sea food chain

Organic compounds synthesized by algae are transferred indirectly or directly to all organisms. The second link in the food chain in the sea is animal filter feeders. The organisms that make up phytoplankton are microscopically small in size (0.002-1mm). They often form colonies, but their size does not exceed five millimeters. The third link is carnivores. They are filter feeders. There are quite a lot of such organisms in the shelf, as well as in the open seas. These, in particular, include siphonophores, ctenophores, jellyfish, copepods, chaetognaths, and carinarids. Among fish, herring should be classified as filter feeders. Their main food is the large aggregations that form in northern waters. The fourth link is considered to be large predatory fish. Some species are of commercial importance. The final link should also include cephalopods, toothed whales and seabirds.

Nutrient transfer

The transfer of organic compounds within food chains is accompanied by significant energy losses. This is mainly due to the fact that most of it is spent on metabolic processes. About 10% of the energy is converted into body matter by the organism. Therefore, for example, the anchovy, which feeds on planktonic algae and is part of an exceptionally short food chain, can develop in such huge quantities as it does in the Peruvian Current. The transfer of food into the twilight and deep zones from the light zone is due to active vertical migrations of zooplankton and certain fish species. Animals moving up and down end up at different depths at different times of the day.

Conclusion

It should be said that linear food chains are quite rare. Most often, ecological pyramids include populations belonging to several levels at once. The same species can eat both plants and animals; carnivores can feed on both first- and second-order consumers; Many animals consume living and dead organisms. Due to the complexity of linkages, the loss of a species often has virtually no effect on the state of the ecosystem. Those organisms that took the missing link for food may well find another source of food, and other organisms begin to consume the food of the missing link. This way the community as a whole maintains balance. A more sustainable ecological system will be one in which there are more complex food chains, consisting of a large number of links, including many different species.

Back forward

Attention! Slide previews are for informational purposes only and may not represent all the features of the presentation. If you are interested in this work, please download the full version.

The purpose of the lesson: To form knowledge about the constituent components of a biological community, about the features of the trophic structure of the community, about food connections that reflect the path of substance circulation, to form the concepts of food chain, food web.

During the classes

1. Organizational moment.

2. Checking and updating knowledge on the topic “Composition and structure of the community.”

On the board: Our world is not an accident, not chaos - there is a system in everything.

Question. What system in living nature is this statement talking about?

Working with terms.

Exercise. Fill in the missing words.

A community of organisms of different species closely interconnected is called …………. . It consists of: plants, animals, …………. , …………. . A set of living organisms and components of inanimate nature, united by the exchange of substances and energy on a homogeneous area of ​​the earth’s surface is called …………….. or …………….

Exercise. Select four components of the ecosystem: bacteria, animals, consumers, fungi, abiotic component, climate, decomposers, plants, producers, water.

Question. How are living organisms connected to each other in an ecosystem?

3. Studying new material. Explain using presentation.

4. Consolidation of new material.

Task No. 1. Slide No. 20.

Identify and label: producers, consumers and decomposers. Compare power circuits and establish similarities between them. (at the beginning of each chain there is plant food, then there is a herbivore, and at the end there is a predatory animal). Name the way plants and animals feed. (plants are autotrophs, i.e. they produce organic matter themselves, animals – heterotrophs – consume finished organic matter).

Conclusion: a food chain is a series of organisms sequentially feeding on each other. Food chains begin with autotrophs - green plants.

Task No. 2. Compare two food chains, identify similarities and differences.

1. Clover - rabbit - wolf
2. Plant litter - earthworm - blackbird - hawk - sparrowhawk (The first food chain begins with producers - living plants, the second with plant residues - dead organic matter).

In nature, there are two main types of food chains: pasture (grazing chains), which begin with producers, detrital (decomposition chains), which begin with plant and animal residues, animal excrement.

Conclusion: Therefore, the first food chain is pasture, because begins with producers, the second is detrital, because starts with dead organic matter.

All components of food chains are distributed into trophic levels. The trophic level is a link in the food chain.

Task No. 3. Make a food chain, including the following organisms: caterpillar, cuckoo, tree with leaves, buzzard, soil bacteria. Indicate producers, consumers, decomposers. (tree with leaves - caterpillar - cuckoo - buzzard - soil bacteria). Determine how many trophic levels this food chain contains (this chain consists of five links, therefore there are five trophic levels). Determine which organisms are located at each trophic level. Draw a conclusion.

• The first trophic level is green plants (producers),
• Second trophic level – herbivores (consumers of the 1st order)
• Third trophic level – small predators (2nd order consumers)
• Fourth trophic level – large predators (3rd order consumers)
• Fifth trophic level - organisms that consume dead organic matter - soil bacteria, fungi (decomposers)

In nature, each organism uses not one food source, but several, but in biogeocenoses food chains intertwine and form food web. For any community, you can draw up a diagram of all the food relationships of organisms, and this diagram will have the form of a network (we consider an example of a food network in Fig. 62 in the biology textbook by A.A. Kamensky and others)

5. Implementation of acquired knowledge.

Practical work in groups.

Task No. 1. Solving environmental situations

1. In one of the Canadian reserves, all wolves were destroyed in order to increase the herd of deer. Was it possible to achieve the goal in this way? Explain your answer.

2. Hares live in a certain territory. Of these, there are 100 small hares weighing 2 kg, and 20 of their parents weighing 5 kg. The weight of 1 fox is 10 kg. Find the number of foxes in this forest. How many plants must grow in the forest for hares to grow up?

3. A reservoir with rich vegetation is home to 2000 water rats, each rat consumes 80g of plants per day. How many beavers can this pond feed if a beaver consumes an average of 200 g of plant food per day?

4. Present the disorderly facts in a logically correct sequence (in the form of numbers).

1. Nile perch began to eat a lot of herbivorous fish.

2. Having multiplied greatly, the plants began to rot, poisoning the water.

3. Smoking Nile perch required a lot of wood.

4. In 1960, British colonists released Nile perch into the waters of Lake Victoria, which quickly multiplied and grew, reaching a weight of 40 kg and a length of 1.5 m.

5. Forests on the shores of the lake were intensively cut down - so water erosion of the soil began.

6. Dead zones with poisoned water appeared in the lake.

7. The number of herbivorous fish decreased, and the lake began to be overgrown with aquatic plants.

8. Soil erosion has led to a decrease in the fertility of fields.

9. Poor soils did not produce crops, and the peasants went bankrupt .

6. Self-test of acquired knowledge in the form of a test.

1. Producers of organic substances in the ecosystem

A) producers

B) consumers

B) decomposers

D) predators

2. To which group do microorganisms living in the soil belong?

A) producers

B) consumers of the first order

B) consumers of the second order

D) decomposers

3. Name the animal that should be included in the food chain: grass -> ... -> wolf

B) hawk

4. Identify the correct food chain

A) hedgehog -> plant -> grasshopper -> frog

B) grasshopper -> plant -> hedgehog -> frog

B) plant -> grasshopper -> frog -> hedgehog

D) hedgehog -> frog -> grasshopper -> plant

5. In a coniferous forest ecosystem, 2nd order consumers include

A) common spruce

B) forest mice

B) taiga ticks

D) soil bacteria

6. Plants produce organic substances from inorganic substances, therefore they play a role in food chains

A) final link

B) initial level

B) consumer organisms

D) destructive organisms

7. Bacteria and fungi play the role of:

A) producers of organic substances

B) consumers of organic substances

B) destroyers of organic substances

D) destroyers of inorganic substances

8. Identify the correct food chain

A) hawk -> tit -> insect larvae -> pine

B) pine -> tit -> insect larvae -> hawk

B) pine -> insect larvae -> tit -> hawk

D) insect larvae -> pine -> tit -> hawk

9. Determine which animal should be included in the food chain: cereals -> ? -> already -> kite

A) frog

D) lark

10. Identify the correct food chain

A) seagull -> perch -> fish fry -> algae

B) algae -> seagull -> perch -> fish fry

C) fish fry -> algae -> perch -> seagull

D) algae -> fish fry -> perch -> seagull

11. Continue the food chain: wheat -> mouse -> ...

B) gopher

B) fox

D) triton

7. General conclusions of the lesson.

Answer the questions:

1. How are organisms interconnected in biogeocenosis (food connections)
2. What is a food chain (a series of organisms sequentially feeding on each other)
3. What types of food chains are there (pastoral and detrital chains)
4. What is the name of the link in the food chain (trophic level)
5. What is a food web (intertwined food chains)

Complex nutritional interactions exist between autotrophs and heterotrophs in ecosystems. Some organisms eat others, and thus carry out the transfer of substances and energy - the basis for the functioning of the ecosystem.

Within an ecosystem, organic matter is created by autotrophic organisms such as plants. Plants are eaten by animals, which in turn are eaten by other animals. This sequence is called a food chain (Fig. 1), and each link in the food chain is called a trophic level.

Distinguish

Grassland food chains(grazing chains) - food chains that begin with autotrophic photosynthetic or chemosynthetic organisms (Fig. 2.). Pasture food chains are found predominantly in terrestrial and marine ecosystems.

An example is the grassland food chain. This chain begins with the capture of solar energy by the plant. The butterfly, feeding on the nectar of a flower, represents the second link in this chain. A dragonfly, a predatory flying insect, attacks a butterfly. A frog hiding among the green grass catches a dragonfly, but itself serves as prey for such a predator as the grass snake. He could have spent the whole day digesting the frog, but before the sun had even set, he himself became the prey of another predator.

The food chain, going from a plant through a butterfly, dragonfly, frog, snake to a hawk, indicates the direction of movement of organic substances, as well as the energy contained in them.

In oceans and seas, autotrophic organisms (unicellular algae) exist only up to the depth of light penetration (maximum up to 150-200 m). Heterotrophic organisms living in deeper layers of water rise to the surface at night to feed on algae, and in the morning they go deeper again, making daily vertical migrations up to 500-1000 m long. In turn, with the onset of morning, heterotrophic organisms from even deeper layers rise to the top to feed on other organisms descending from the surface layers.

Thus, in the deep seas and oceans there is a kind of “food ladder”, thanks to which organic matter created by autotrophic organisms in the surface layers of water is transported along the chain of living organisms to the very bottom. In this regard, some marine ecologists consider the entire water column to be a single biogeocenosis. Others believe that environmental conditions in the surface and bottom layers of water are so different that they cannot be considered as a single biogeocenosis.

Detrital food chains(decomposition chains) - food chains that begin with detritus - dead remains of plants, corpses and animal excrement (Fig. 2).

Detrital chains are most typical for communities of continental reservoirs, the bottom of deep lakes, oceans, where many organisms feed on detritus formed by dead organisms of the upper illuminated layers of the reservoir or that entered the reservoir from terrestrial ecosystems, for example, in the form of leaf litter.

The ecosystems of the bottom of the seas and oceans, where sunlight does not penetrate, exist only due to the constant settling there of dead organisms living in the surface layers of water. The total mass of this substance in the World Ocean per year reaches at least several hundred million tons.

Detrital chains are also common in forests, where most of the annual increase in the live weight of plants is not consumed directly by herbivores, but dies, forming litter, and is then decomposed by saprotrophic organisms, followed by mineralization by decomposers. Fungi are of great importance in the decomposition of dead plant matter, especially wood.

Heterotrophic organisms that feed directly on detritus are called detritivores. In terrestrial ecosystems they are many species of insects, worms, etc. Large detritivores, which include some species of birds (vultures, crows, etc.) and mammals (hyenas, etc.) are called scavengers.

In aquatic ecosystems, the most common detritivores are arthropods - aquatic insects and their larvae, and crustaceans. Detritivores can feed on other, larger heterotrophic organisms, which themselves can serve as food for predators.

Trophic levels

Typically, different trophic levels in ecosystems are not separated in space. However, in some cases they are quite clearly differentiated. For example, in geothermal sources, autotrophic organisms - blue-green algae and autotrophic bacteria, forming specific algal-bacterial communities ("mats") are common at temperatures above 40-45 ° C. At lower temperatures they do not survive.

On the other hand, heterotrophic organisms (mollusks, larvae of aquatic insects, etc.) are not found in geothermal springs at temperatures above 33-36 ° C, so they feed on fragments of mats carried by the current to areas with lower temperatures.

Thus, in such geothermal sources, an autotrophic zone is clearly distinguished, where only autotrophic organisms are common, and a heterotrophic zone, where autotrophic organisms are absent and only heterotrophic organisms are found.

Trophic networks

In ecological systems, although there are a number of parallel food chains, e.g.

herbaceous vegetation -> rodents -> small predators
herbaceous vegetation -> ungulates -> large predators,

which unite the inhabitants of the soil, herbaceous cover, tree layer, there are other relationships. In most cases, the same organism can serve as a food source for many organisms and thus be part of different food chains and prey to different predators. For example, daphnia can be eaten not only by small fish, but also by the predatory crustacean Cyclops, and roach can be eaten not only by pike, but also by otter.

The trophic structure of a community reflects the relationship between producers, consumers (separately of the first, second, etc. orders) and decomposers, expressed either by the number of individuals of living organisms, or their biomass, or the energy contained in them, calculated per unit area per unit time.