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 an abiotic and biotic part. 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 energy transformation. Its main source is sunlight. Photosynthetic organisms use it to synthesize organic substances. Heterotrophs obtain energy from the breakdown of organic substances. Only a small part of it is used for growth. And the rest is spent for existence of life processes.
As a result, sequences are formed in which individuals of some species, their remains, or are a source of food for others. These are called trophic or food chains.
Trophic levels
Each power chain consists of a certain number of links. It has been established that when moving 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 into groups. These include representatives of absolutely all kingdoms of living nature, regardless of their level of organization. Let's look at each of them.
Consumers: orders
Heterotrophs occupy different levels in the food chain. All herbivorous species are the Next level are carnivores. They are already second-order consumers.
Let's look at this hierarchy using a specific example. Let's say the food web looks like this: mosquito, frog, stork. Which one of them is a consumer of the first order? This is a frog. Then the stork is a consumer of the second order. 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 food they eat. Let us consider another group of the trophic network 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: autotrophs and chemotrophs. The first use the energy of sunlight to create organic matter. These are plants, cyanobacteria, and some protozoa. Chemotrophs have the ability to oxidize various chemical compounds. At the same time, energy is generated, which they use to produce waste products. These include nitrogen-fixing, sulfur, and 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, which feed on organic matter from the remains or waste products of other species, which they decompose into minerals. This function is performed by decomposers. Representatives of this group are bacteria and fungi.
It is at the level of producers in the ecosystem that energy accumulation occurs. It then passes through consumers and producers, where it is consumed. At each subsequent trophic level, part of the energy is dissipated as heat.
Types of power circuits
The energy in an ecosystem is divided into two streams. The first is directed to consumers from producers, the second - from dead organic matter. Depending on this, trophic networks of pasture and detritus types are distinguished. In the first case, the initial trophic level consists of producers who transfer energy to consumers of different levels. The pasture chain ends with decomposers.
The detrital 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, many trophic chains simultaneously exist. 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. Thanks to this, trophic networks are formed. And the more branched they are, the more stable the ecosystem.
The food chain has a certain structure. It includes producers, consumers (first, second order, etc.) and decomposers. More details about consumers will be discussed in the article. In order to thoroughly understand who consumers of the 1st order, 2nd order and beyond are, we first briefly consider the structure of the food chain.
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 given to organisms that producers consume as food. They will be discussed in detail below.
And finally, decomposers are the final tier of the food pyramid, the last link in the chain, “orderly” organisms. This is an integral and very important component of the ecosystem. They process and decompose high-molecular organic compounds into inorganic ones, which are then reused by autotrophs. Most of them are organisms of fairly small size: insects, worms, microorganisms, etc.
Who are consumers
As mentioned above, consumers are located on the second tier of the food pyramid. These organisms, unlike producers, do not have the ability for photo- and chemosynthesis (the latter is understood as the process by which archaea and bacteria obtain 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 are consumers of the 1st order
This link in the food chain includes heterotrophs, which, unlike decomposers, are not capable of decomposing organic substances into inorganic ones. The so-called primary consumers (1st order) are those that directly feed on the biomass producers themselves, that is, producers. These are primarily herbivores - 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 humans in agriculture: cattle, horses, rabbits, sheep.
Among wild animals, the beaver is a phytophagous animal. It is known that it uses tree trunks to build dams, and uses their branches for food. Some species of fish, such as grass carp, are also herbivores.
Plants are consumers of the first order
To summarize, we can draw the following conclusion: consumers are organisms that feed on plants.
Second order consumers and beyond
In turn, consumers of the 3rd order are those who eat consumers of the previous order, that is, larger predators, of the 4th are 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 producing organism to the consumer at the previous levels are quite large. After all, they are inevitable at every level.
It is also often difficult, and sometimes impossible, to draw a clear boundary between consumers of certain orders. After all, some animals are simultaneously consumers of different levels.
Also, many of them are omnivores, 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, he may, for example, eat food only of plant origin.
In aquatic ecosystems, the main producers are algae - often small single-celled organisms that make up the phytoplankton of the surface layers of oceans and lakes. On land, most of the primary production is supplied by more highly organized forms related to gymnosperms and angiosperms. They form forests and meadows.
4.2. Primary consumers
Primary consumers feed on primary producers, i.e. they are herbivores. On land, typical herbivores include many insects, reptiles, birds and mammals. The most important groups of herbivorous mammals are rodents and ungulates. The latter include grazing animals such as horses, sheep, and cattle, which are adapted to running on their toes.
In aquatic ecosystems (freshwater and marine), herbivorous forms are usually represented by mollusks and small crustaceans. Most of these organisms—cladocerans, copepods, crab larvae, barnacles, and bivalves (such as mussels and oysters)—feed by filtering tiny primary producers from the water. Together with protozoa, many of them form the bulk of the zooplankton that feed on phytoplankton. Life in oceans and lakes depends almost entirely on plankton, since almost all food chains begin with it.
4.3. Second and third order consumers
Plant material ( for example, nectar) → fly → spider →
→ shrew → owl
Rosebush sap → aphid → ladybug → spider → insectivorous bird → bird of prey
4.4. Decomposers and detritivores (detritus food chains)
There are two main types of food chains – grazing and detrital. Above were examples of pasture chains in which the first trophic level is occupied by green plants, the second by pasture animals and the third by predators. The bodies of dead plants and animals still contain energy and “building material,” as well as intravital excretions, such as urine and feces. These organic materials are decomposed by microorganisms, namely fungi and bacteria, living as saprophytes on organic residues. Such organisms are called decomposers. They release digestive enzymes onto dead bodies or waste products and absorb the products of their digestion. The rate of decomposition may vary. Organic matter from urine, feces and animal carcasses is consumed within weeks, while fallen trees and branches can take many years to decompose. A very significant role in the decomposition of wood (and other plant debris) is played by fungi, which secrete the enzyme cellulase, which softens the wood, and this allows small animals to penetrate and absorb the softened material.
Pieces of partially decomposed material are called detritus, and many small animals (detritivores) feed on them, speeding up the decomposition process. Since both true decomposers (fungi and bacteria) and detritivores (animals) are involved in this process, both are sometimes called decomposers, although in reality this term refers only to saprophytic organisms.
Larger organisms can, in turn, feed on detritivores, and then a different type of food chain is created - a chain, a chain starting with detritus:
Detritus → detritivore → predator
Detritivores of forest and coastal communities include earthworm, woodlice, carrion fly larva (forest), polychaete, scarlet fly, holothurian (coastal zone).
Here are two typical detrital food chains in our forests:
Leaf litter → Earthworm → Blackbird → Sparrowhawk
Dead animal → Carrion fly larvae → Grass frog → Common grass snake
Some typical detritivores are earthworms, woodlice, bipeds and smaller ones (<0,5 мм) животные, такие, как клещи, ногохвостки, нематоды и черви-энхитреиды.
5. Food webs
In food chain diagrams, each organism is represented as feeding on other organisms of one type. However, actual food relationships in an ecosystem are much more complex, since an animal may feed on different types of organisms from the same food chain or even from different food chains. This is especially true for predators of the upper trophic levels. Some animals eat both other animals and plants; they are called omnivores (this is the case, in particular, with humans). In reality, food chains are intertwined in such a way that a food (trophic) web is formed. A food web diagram can only show a few of the many possible connections, and it usually includes only one or two predators from each of the upper trophic levels. Such diagrams illustrate nutritional relationships between organisms in an ecosystem and provide the basis for quantitative studies of ecological pyramids and ecosystem productivity.
6. Ecological pyramids.
6.1. Pyramids of numbers.
To study the relationships between organisms in an ecosystem and to graphically represent these relationships, it is more convenient to use ecological pyramids rather than food web diagrams. In this case, the number of different organisms in a given territory is first counted, grouping them by trophic levels. After such calculations, it becomes obvious that the number of animals progressively decreases during the transition from the second trophic level to subsequent ones. The number of plants at the first trophic level also often exceeds the number of animals that make up the second level. This can be depicted as a pyramid of numbers.
For convenience, the number of organisms at a given trophic level can be represented as a rectangle, the length (or area) of which is proportional to the number of organisms living in a given area (or in a given volume, if it is an aquatic ecosystem). The figure shows a population pyramid reflecting the real situation in nature. Predators located at the highest trophic level are called final predators.
Fourth trophic level Tertiary consumers
Trophic structure of ecosystems.
Source: training manual “Island” (there is a little in lecture 3).
Answer:
Autotrophic nutrition(autonomous nutrition) – synthesis of organic substances from inanimate nature (carbon dioxide and water) through photosynthesis (photoautotrophic organisms) and chemosynthesis (chemoautotrophs).
TO photoautotrophs include all green plants and some bacteria (examples of autotrophs: moss, trees, phytoplankton). In the process of life, they synthesize organic substances in the light - carbohydrates or sugars (CH 2 O) n. The main role in the synthesis of organic substances belongs to plant organisms; they are fully responsible for the formation of all new organic matter in any ecosystem. Every year, photosynthetic organisms on Earth create about 150 billion tons of organic matter that accumulates solar energy.
Chemoautotrophs(live in the soil and subsoil) use the energy released during chemical reactions of oxidation of hydrogen, sulfur, hydrogen sulfide, ammonia, etc., and synthesize the organic substances they need. This group includes nitrifying bacteria that oxidize ammonia to nitrous and then nitric acids.
Heterotrophic nutrition(feeding on others) – consumption of finished organic matter. Heterotrophs include all animals, fungi and most bacteria. Heterotrophs act as consumers and destroyers (destructors) of organic substances. Depending on their food sources and participation in the destruction of organic matter, they are divided into consumers, detritivores (saprotrophs), and decomposers.
Consumers– consumers of organic matter of living organisms. Consumers are a wide variety of organisms: from bacteria to elephants. These include protozoa, worms, fish, mollusks, arthropods, birds, mammals, including humans. Consumers are divided into a number of subgroups according to differences in food sources.
The activities of consumers contribute to the transformations and movements of organic substances in ecosystems, their partial mineralization, as well as the dissipation of energy accumulated by producers.
Consumers include symbiotrophs(bacteria and fungi) that feed on plant root secretions. Symbiotrophs play a significant role in the functioning of ecosystems. Fungal threads entangling plant roots help absorb water and minerals. Symbiotrophic bacteria absorb nitrogen from the atmosphere and convert it into compounds available to plants (ammonia, nitrates). This nitrogen is called biological. Symbiotrophs include bacteria, single-celled organisms that live in the intestines of humans and phytophagous animals; they help them digest food.
Detritivores (saprotrophs)– organisms that feed on dead organic matter – the remains of plants and animals (detritus). These are various putrefactive bacteria, fungi, worms, centipedes, fly larvae, crayfish, crabs, jackals and other animals - they all perform the function of cleansing ecosystems. Detritivores are also consumers.
Some organisms use both plants and animals and even detritus for food; they belong to euryphages (omnivores)– bear, fox, pig, rat, chicken, crow, cockroach, etc.
Decomposers– bacteria and lower fungi – complete the destructive work of detritivores, bring the decomposition of organic matter to inorganic compounds (mineral) – carbon dioxide, water, etc. They return mineral substances to the ecological system, return substances to the cycle, transforming them into forms accessible to producers (autotrophs). The role of decomposers in the cycle of substances is extremely large. Without decomposers, piles of organic residues would accumulate in the biosphere; the reserves of mineral substances needed by producers would dry up, and life in the form that we know would cease.
In any ecosystem, all detritivores and decomposers perform the same function - they feed on dead organic matter, decompose it and ultimately transform it into inorganic substances, which serve as feedstock for feeding producers. Detritivores and decomposers, based on the type of nutrition, are classified into a special group of organisms - saprophages(feed on dead organic matter).
All of these groups of organisms in any ecosystem closely interact with each other, coordinating the flows of matter and energy. Their joint functioning not only maintains the structure and integrity of the ecosystem, but also has a significant impact on the abiotic components of the system, contributing to its purification.
(producers). Unlike decomposers, consumers are not able to decompose organic substances into inorganic ones.
An individual organism can be a consumer of different orders in different trophic chains, for example, an owl eating a mouse is simultaneously a consumer of the second and third order, and a mouse is a consumer of the first and second, since the mouse feeds on both plants and herbivorous insects.
Any consumer is heterotroph, since it is not able to synthesize organic substances from inorganic ones. The term “consumer (first, second, and so on) order” allows you to more accurately indicate the place of the organism in the food chain. Reducers (for example, fungi, decay bacteria) are also heterotrophs; they are distinguished from consumers by the ability to completely decompose organic substances (proteins, carbohydrates, lipids and others) to inorganic ones (carbon dioxide, ammonia, urea, hydrogen sulfide), completing the cycle of substances in nature, creating a substrate for the activity of producers (autotrophs).
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Excerpt characterizing Consumers
-Can I get a book? - he said.- Which book?
- Gospel! I have no.
The doctor promised to get it and began asking the prince about how he felt. Prince Andrei reluctantly, but wisely answered all the doctor’s questions and then said that he needed to put a cushion on him, otherwise it would be awkward and very painful. The doctor and the valet lifted the greatcoat with which he was covered and, wincing at the heavy smell of rotten meat spreading from the wound, began to examine this terrible place. The doctor was very dissatisfied with something, changed something differently, turned the wounded man over so that he groaned again and, from the pain while turning, again lost consciousness and began to rave. He kept talking about getting this book for him as soon as possible and putting it there.
- And what does it cost you! - he said. “I don’t have it, please take it out and put it in for a minute,” he said in a pitiful voice.
The doctor went out into the hallway to wash his hands.
“Ah, shameless, really,” the doctor said to the valet, who was pouring water onto his hands. “I just didn’t watch it for a minute.” After all, you put it directly on the wound. It’s such a pain that I’m surprised how he endures it.
“It seems like we planted it, Lord Jesus Christ,” said the valet.
For the first time, Prince Andrei understood where he was and what had happened to him, and remembered that he had been wounded and how at that moment when the carriage stopped in Mytishchi, he asked to go to the hut. Confused again from pain, he came to his senses another time in the hut, when he was drinking tea, and then again, repeating in his memory everything that had happened to him, he most vividly imagined that moment at the dressing station when, at the sight of the suffering of a person he did not love, , these new thoughts came to him, promising him happiness. And these thoughts, although unclear and indefinite, now again took possession of his soul. He remembered that he now had new happiness and that this happiness had something in common with the Gospel. That's why he asked for the Gospel. But the bad situation that his wound had given him, the new upheaval, again confused his thoughts, and for the third time he woke up to life in the complete silence of the night. Everyone was sleeping around him. A cricket screamed through the entryway, someone was shouting and singing on the street, cockroaches rustled on the table and icons, in the autumn a thick fly beat on his headboard and near the tallow candle, which had burned like a large mushroom and stood next to him.