One of the most important aspects that govern the natural world is the food chain. This phenomenon dictates how matter and energy (in the form of food) flow between organisms. When more than a few food chains intertwine in an environment, it forms a food web. In this article, we shall explore how a food chain works, its components and implications for the natural world.

How Do You Define a Food Chain?

A food chain can be defined as a sequence of transfers of energy and matter from one organism to another. This transfer of energy and matter occurs through food.

How Many Levels are Present on a Food Chain?

A food chain does not have an infinite number of levels. This is because a significant amount of energy is lost as heat between each trophic level. This means that very little usable energy remains after about four or five trophic levels. Hence, most trophic levels are restricted to only five levels or less.

What is the Initial Source of Energy in a Food Chain?

For energy to be consumed, energy must be produced. On earth, the biggest source of energy is the sun. Even organisms that produce their own food, such as autotrophs must rely on the sun for their photosynthesis process. Without the sun, life may cease to exist. Even if sunlight was somehow blocked from reaching earth (due to cataclysmic events such as massive volcanic eruptions), plantlife will start to perish. In fact, one of the most recent mass extinctions on earth was the K–T extinction (Cretaceous–Tertiary extinction). This event wiped out nearly 80% of all animal species on earth about 66 million years ago. One of the primary reasons for extinction was that sunlight had been blocked out due to extreme weather events which was brought about by an asteroid impact.

What are the Components of a Food Chain?

Most food chains have the following components:

  • Producers
  • Consumers
  • Decomposers


As the name suggests, producers are the organisms that create their own food. Most producers use the process of photosynthesis while other organisms may resort to chemosynthesis. On land, green plants are considered to be producers – they make energy by using sunlight and water to produce usable energy. In aquatic ecosystems, kelps, phytoplankton and algae form the primary producers.


Consumers are the organisms that depend on the producers for food. These include all animal species – right from heterotrophic amoeba to blue whales and birds. Since animals also consume other animals, consumers are classified as follows:

  • Primary consumer (grasshopper)
  • Secondary consumer (rat)
  • Tertiary consumer (snake)
  • Quaternary consumer (hawk)

It is important to note that as energy flows from one organism to the next, energy is lost at each trophic level.


When any organism dies, their body is converted back into usable materials and nutrients by decomposers. Fungi are well-known decomposers – they break down dead organic matter and return nutrients to the soil. In other words, fungi help to cycle nutrients through an ecosystem, and if not for them, the entire ecosystem would collapse. Interestingly, besides fungi, there are also saprophytic plants which perform this role – examples of such plants include Corallorhiza orchids (Corallorhizatrifida) and the Indian pipe (Monotropauniflora). Though these are angiosperms, they are unable to produce their own food as they do not contain enough chlorophyll – making photosynthesis unlikely. Explore other fascinating topics by registering at BYJU’S biology.