The food chain or food chain point out the food relations between producers, consumers and decomposers . In other words, the chain it reflects who eats whom (a living being feeds on the one who precedes it in the chain and, at the same time, is eaten by the one who follows it).
It is, in short, a current of Energy which begins with photosynthesis and then is transferred from one organism to another through the nutrition . The food chain, therefore, begins with photosynthetic vegetables, which have the ability to create living matter from inert. Therefore, they are called producers .
Autotrophs is what these producers are also called among which we can emphasize that the plants are found.
In the next link in the chain we find the animals that feed on the producers and that are called primary consumers or phytophagous . Herbivorous beings are those who consider them to be primary consumers because they are the ones that feed on the producers, the plants. Among them we could highlight, for example, insects. These animals serve as food for others that are known as secondary consumers or carnivores .
And then we could also talk about tertiary consumers who are those who basically feed on secondary ones. Among those we could highlight that there are all those animals and beings of the ecosystem that exert superiority over the rest, as would be the case of superpredators such as crocodile, shark, jaguar, polar bear, wolf or lion.
To close the chain, the bacteria and mushrooms that break down plant and animal waste. With this decomposition, simple elements reappear that are used as food by plants.
However, to all of the above, it should be added that up to seven levels can be established in this food chain if actions or phenomena such as commensalism or decomposition are taken into account.
To be able to understand perfectly how the food chain works and to be able to work with it in a much easier way, it is often represented by the so-called trophic pyramid. It is an element, in the form of said geometric object, where each of the aforementioned levels is ordered according to a criterion from highest to lowest. That is, at the top of it will appear the upper level, that of the superpredators, and so it will continue down until it reaches the base of the pyramid where the beings called producers are located.
In a food chain, all beings have great importance. With the disappearance of a link, the beings that follow will run out of food. On the other hand, living beings that are at the level immediately before the missing link will begin to experience an overpopulation, since they will not have their predator. That is why the protection of ecosystems and of all its components.