Food Web

Energy can be stated as the power to do things. This power can be derived in many ways and multiple forms, but all of them can be easily linked to the sun. The Sun is the source of all the energy and no energy can be produced without it. 

The living organisms present in the ecosystem can either make their own food or depend on others to make food for them. Plant, for example capture solar energy and through the process of photosynthesis prepares their own food. Due to this reason the plants are called producers or autotrophs. Other organisms consume these green plants to obtain energy and are termed as heterotrophs.

What is a Food Web?

Various components of the ecosystem with the help of sun produces energy. The energy, when produced and stored is continuously distributed among the various living organisms. This process of transfer of energy is referred to as food web. Food web demonstrates the flow of energy through different organisms in the ecosystem. Food web is able to depict the multiple food chains that are linked together to illustrate the feeding relationships among the organisms in the ecosystem. Another name for food web is Consumer-Resource system. 

Food web can be described as the natural interconnection of several food chains. It can also be stated as the graphical representation of which what is eaten by the members of the ecological community. The connections between the food webs depict the feeding pathways such as where the heterotrophs obtain organic matter by feeding on the autotrophs. The food web presents a picture of the various ways of feeding which connects the ecosystem into a single unified system.

What is a Food Chain?

A food chain can be described as a linear sequence of organisms, where the cycle starts with the producers and ends with the decomposers. Food chain allows us to understand how various organisms of the ecosystem are connected to each other. Food chain is the chronological order that demonstrates the flow of energy from organism to organism. Our ecosystem comprises of producers, consumers, and decomposers and thus, the pathway for the flow of energy is very specific. The energy once created is never destroyed rather; it is transferred from one organism to another. Food chain shows the single path that passes through the producers to the consumers and the flow of the energy in this way. 

When more than one food chain occurs in the ecosystem, it is termed as the food web. Food chain depicts the direct transfer of energy from organism to organism. But as each organism feeds upon multiple things, the food web is considered more realistic and simple method for the transfer of the energy. Food chains and food web are similar but they are not the same. The common feature that is shared by both food chain and food web are the type of organisms. There are three types of organisms present in the food chain – producers, consumers and decomposers. 

Producers 

Producers, as we have discussed earlier are those organisms who are capable of synthesizing their own food with the help of solar energy. Plants, algae and some bacteria fall into this category. These organisms produce their own food by converting sunlight into chemical energy and this process is termed as photosynthesis. Plants use the energy from sunlight to convert CO2 into simple glucose which easily breaks down to produce energy. This energy is stored in the form of sugar to be used later. 

Consumers

Consumers are the organisms that derive energy by eating other organisms. The consumers can feed on both plants and / or animals. In a food chain, the producers are always on the lowest step and the first step after them is occupied by primary consumers. The primary consumers are the ones that feed on the producers and are known as herbivores. Some examples of herbivores are insects, deer, cow elephant etc.
 
After the primary consumers, comes the secondary consumers who survive by eating the primary consumers. They generally eat meat and are known as the predators. Animals like lions, tigers, wolves, spiders etc. are some of the secondary consumers. 

There exists a third category of consumers known as the tertiary consumers. These are known to be feeding on the secondary consumers and are termed as the apex predators. The tertiary consumers can be both carnivores and omnivores. For example, a hawk can feed on another bird or on a snake which is a secondary consumer. 

Why are humans not at the top of the Food Chain?

One can easily assume that the humans are sat at the top of the food chain but the fact is that it is not true. Ecologists have a statistical method for calculating the Trophic Level of a species in the food chain. Trophic Level represents the position of an organism in the food chain in respect to the lowest level of the same. The predators in a community generally apply a top – down control on the organisms. But humans are not considered the apex predators owing to their different forms of diet. However, the human trophic levels keep rising with the consumption of meat. 

The producers or the plants are placed at the trophic level 1 by the ecologists. The apex producers rank higher and are placed at level 4 or level 5. As per the calculations of the scientists the humans are placed at a trophic level of 2.21.

Summary

  • Energy is essential for all processes and sun is the main source of all the energy.

  • The process through which energy is transferred from one organism to another is termed as food web.

  • A food chain can be described as a linear sequence of organisms, where the cycle starts with the producers and ends with the decomposers.

  • The apex predators are ranked at level 4 or 5.

  • Humans are not apex predators and are placed at the trophic level 2.21.