Any living organism chooses the conditions that are most favorable for its habitat and provide it with the opportunity to fully eat. The fox chooses a place of residence where many hares live. The lion settles closer to the herds of antelopes. The sticky fish not only travels attached to the shark, but also dine with it.
Plants, although they are deprived of the opportunity to consciously choose a habitat, but mostly also grow in the most comfortable places for themselves. Gray alder is often accompanied by nettle, which is demanding on nitrogen nutrition. The fact is that alder cohabitates with bacteria that enrich the soil with nitrogen.
The food web is a kind of symbiosis
Here we are faced with a certain kind of relationship. This is the so-called symbiosis. It is a direct relationship in which both organisms benefit. They are also called food webs and chains. Both terms have a similar meaning.
What is the difference between foodchain and food web? Separate groups of organisms (mushrooms, plants, bacteria, animals) constantly exchange certain substances and energy with each other. This process is called the food chain. The exchange between groups is carried out while eating one by the other. The process of interaction between such chains is called a food web.
How organisms are interconnected
It is known that leguminous plants (clover, mouse peas, caragana) cohabit with nodule bacteria that convert nitrogen into forms that are absorbed by plants. In turn, the bacteria receive the organic matter they need from the plants.
A similar relationship develops between flowering plants and fungi. It is no coincidence that many of them are called boletus, boletus, oak. Sometimes mycorrhizal fungi are an indispensable factor that ensures seed germination. This is especially important for the orchid family. In the tropics, the little heron feeds on parasites, pecking them off ungulates. Some hymenoptera extract nectar from the flowers of legumes, for which they are the only pollinators.
Examples of food webs
Many of the relationships described are of a specific nature. However, in each biocenosis there are relationships in which each population takes part. These are food or trophic (trophos - food) relationships.
Examples of food webs and chains:
- Many animals eat plant foods. They are called herbivores, herbivores,granivorous.
- There are animals that eat other animals. They are called carnivores, predators, insectivores.
- There are predatory bacteria and fungi.
- Many animals, bacteria, viruses, fungi, and sometimes plants not only feed on other organisms, but also live on them. These are parasites (parasitos are freeloaders).
- Finally, numerous bacteria and fungi feed on organic residues. These are saprotrophs (sapros is rotten).
In all cases, an organism that feeds on others gains one-sided benefits. Participating in the process of nutrition, all individuals of the population provide themselves with the energy and various substances necessary for their life activity. A population serving as an object of food is negatively affected by predators that devour it.
Autotrophs and heterotrophs
Recall that organisms are divided into two groups according to the way they feed.
Autotrophic (autos - self) organisms live off an inorganic source of hydrocarbons. This group includes plants.
Heterotrophic (heteros - different) organisms live off the organic source of hydrocarbons. This group includes fungi and bacteria. If autotrophs are independent of other organisms in the source of carbon and energy, then heterotrophs are completely dependent on plants in this regard.
Competitive relations between groups
Relationships that lead to the oppression of one of the partners are not necessarily related to nutritional relationships. Many weeds secrete growth retardant metabolitesplants. Dandelion, couch grass, cornflower depressing effect on oats, rye and other cultivated cereals.
Populations of many species live in each biocenosis, and the relationships between them are diverse. We can say that the population is limited in its capabilities by these relationships and must find its own place.
The level of provision of habitat with ecological resources determines the possibility of the existence of many niches. The number of species populations forming a biocenosis also depends on this. In the conditions of a favorable climate of the steppes, biocenoses are formed, consisting of hundreds of species, and in the tropical climate of the forest - from a thousand species of organisms. Desert biocenoses in a hot climate include several dozen species.
The spatial distribution of populations is just as variable. Tropical forests are multi-tiered, and living organisms fill the entire volume of space. In deserts, biocenoses are simple in structure, and populations are small. Thus, it is clear that the joint life of organisms in biocenoses is unusually complex. And yet, plants and animals, fungi and bacteria are combined into biocenoses and exist only in their composition. What are the reasons for this?
The most important of them is the need of living organisms for nutrition, in trophic dependence on each other.
