Living beings need to provide themselves with energy to carry out all their basic processes, grow, breathe, reproduce, etc. This energy is obtained through nutrients, however, not all living beings capture the necessary energy in the same way, they obtain it in different ways, depending on whether they are producers, consumers or decomposers. In this way, a whole series of alimentary relationships are established that are known as trophic relationships or trophic levels. In this way, the flow of nutrients is produced that guarantees the supply and circulation of the substances necessary to sustain life on the planet.
Once all these differences are understood, let's move on to define what are trophic levels. The trophic levels are nothing more than each one of the different sets of living beings, categorized according to the way in which they obtain their nutrients. The trophic levels are then, the food relationships that are established between organisms and that allow organizing and categorizing each group of individuals, according to the way they obtain their nutrients.
Determination of trophic levels
The individuals of the different species that make up a community, depending on the type of food they require, are grouped as follows:
First level (Producers)
At this level we find those individuals capable of making their own food, that is, the producing or autotrophic organisms. These organisms are capable of directly capture energy from the primary source, the sun. Autotrophic organisms have the particularity of taking advantage of the presence of carbon dioxide, water, other minerals and sunlight to synthesize their own organic compounds: carbohydrates, through photosynthesis. Plants, algae, and photosynthetic microorganisms are in this group. The food they produce can be used, directly or indirectly, by other organisms in ecosystems. Producing organisms constitute the trophic level lower, they are the base on which the upper levels are based. They are the only ones that, through photosynthesis, They are capable of capturing solar energy and transforming it into chemical energy.
Second level (Consumers)
At this level we find the primary consumers. This group is made up of all those individuals that obtain their nutrients from the producers, that is, they feed on parts of vegetables such as: leaves, flowers and fruits. These are also called herbivores. Consuming organisms are heterotrophic, they manufacture their organic matter from organic matter that comes from other living beings, that is why they are called consumers. They are also producers (they make their own organic matter), but they are not primary producers. In turn, consumers can also be the source of organic matter for other consumers who feed on them.
Third level (secondary consumers)
This group is made up of secondary consumers who feed directly from the primary consumers. They are also called carnivores. Secondary consumers also differ in the type of diet they consume.
- Lions and tigers hunt zebras, impalas, deer, and other small mammals for food.
- Snakes, in general, feed on small rodents, amphibians, and bird eggs.
- Birds, such as the hawk, owl, and eagle, feed on snakes and lizards. While many smaller birds eat butterfly larvae and earthworms.
- Spiders catch small insects, like flies and moths.
- In the sea some animals, such as sharks and whales, feed on smaller fish.
Fourth level
Tertiary consumers or higher. They feed off secondary consumers. They are large predators that feed on primary consumers (herbivores) and secondary (carnivores). They are also called predators.
Transversal level (decomposers)
Decomposing organisms, as their name implies, exert their action on debris, remains of dead plants, animal corpses, etc., and thus obtain the energy they need to live. At this level, we find the fungi and bacteria that decompose the organic matter of dead individuals into mineral substances. Most microscopic fungi are saprophytes; among them we have the stick ear, the little hat fungus, the bread mold and the mushroom. As a consequence of decomposition, carbon dioxide is released into the atmosphere and minerals such as calcium, potassium, phosphorus and nitrogen, etc. are released into the soil, in the waters. they were constituting the organism, tissue, debris, etc. In this way, the cycle of nutrients and carbon dioxide is completed, and all the elements are left free to pass back to the producers and continue like this, cycle after cycle. Oxygen is another necessary component for living matter, it is released by producers in photosynthesis and captured by themselves, by consumers and decomposers, in cellular respiration. The decomposers constitute an important link for the continuity of the biogeochemical cycles, since if they do not decompose the organic matter, it would be trapped, with which it could not be assimilated again by living organisms. In this way, little by little the nutrients would disappear, and with them the producers: and along with them the consuming organisms. On the other hand, there are animals, such as the vulture, the zamuro, the hyena, etc., that although they are consuming organisms, collaborate with the decomposers to eliminate animal remains since these animals only feed on the meat of dead animals. This is another medium, through which nutrients circulate through trophic levels in ecosystems.
Energy flow
Not all organisms have the ability to capture the sun's energy and transform it into chemical energy from food, so that living beings fulfill their vital functions. The producers are the only ones capable of making the energy of the sun available to the rest of the species of the biological community. From them the energy flows unidirectionally towards the consumers and the decomposers that make up the food chain. The biological flow of energy refers to the passage of the chemical energy contained in food, from the lower trophic level, where the producers are located, to the higher trophic levels occupied by the consumers.
Energy is not recycled
The amount of energy transferred between trophic levels to another represents approximately 10% of the available energy, which causes serious limitations in terms of the number and size of organisms that can be part of a trophic chain 90% of the energy remaining that is not transferred, is lost as heat and cannot be reused. This results in energy, unlike matter, not being recoverable. Hence, a constant incorporation of energy into the biological community is necessary to ensure the continuity of its existence. As this function is exercised by the producers who take it from the Sun, these organisms are recognized as the pillars of the community and the ecosystem.
Matter is recycled
The matter that living beings use comes from the ground, air and water. In all trophic relationships, in addition to energy, matter is transferred from one level to another. But matter as opposed to energy if it is recycled. This happens thanks to the processes of photosynthesis and respiration that recycle oxygen, hydrogen and carbon to the air and water and also to the existence of decomposers that recycle other mineral substances to the soils and allow them to be used again by producers, thus closing the cycle of matter.