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Classification of Organisms | Foodchain

Aug 19, 2022

Key Concept

  • Producers
  • Consumers
  • Primary, secondary, tertiary consumers
  • Decomposers
  • Scavengers


All living organisms need energy. Energy is the ability to do work. Living organisms need the energy to perform various processes. The sun is the ultimate source of energy for all the living organisms on the earth. 

Fig 1

Plants use sunlight to make their food and to get energy. Photosynthesis is the process in which plants use energy from the sunlight, carbon dioxide from the air, and water from the soil to make their food. Organisms that can make their own food are called autotrophs, and organisms that depend on other organisms to get food are called heterotrophs. Plants and some microorganisms are autotrophs, while the rest are heterotrophs. 

Fig 2

What is a food chain? 

A food chain shows how energy passes from one organism to another as food. The plant uses the energy from the sunlight to make its own food. Then an animal such as a grasshopper eats the plant. Then the frog eats grasshopper to get energy. The energy passes from the sun to the plant, to the insect, to the frog. 

Fig 3

In an ecosystem, animals can be of three types based on their food type.  

  • Herbivore: Eat only plants like goat, deer, rhino, elephant, etc.  
  • Carnivore: Eat only meat or flesh like tiger, insects, lion, etc.  
  • Omnivore: Eat both plants and animals like bears, humans, pigs, etc. 
Fig 4

Classification of organisms  

In a food chain, organisms can be classified into the following categories:  

  • Producers  
  • Consumers  
  • Decomposers  


These are organisms that directly use sunlight to get energy. Green plants in a food chain are called producers. They are called this because they make, or produce, their own food.  

Producers use simple components from the surroundings to make food. Producers are also known as autotrophs. Examples of producers are plants and microorganisms like algae.  

Fig 5


Organisms that depend on other living organisms to obtain energy are called consumers. Animals cannot make their own food. They must eat or consume plants or other animals for food. Consumers are also called heterotrophs. 

Fig 6

Consumers can be of three types: 

Primary Consumer Secondary Consumer Tertiary Consumer 
Primary consumers always depend on producers for food.  Secondary consumers rely on primary consumers for energy. Tertiary consumers are organisms that rely on secondary consumers for food. 
They are always herbivore They can either be carnivores or omnivores. They can either be carnivores or omnivores. 
Goats, insects Frogs, humans Eagle, snakes, tiger 
Fig 7


Organisms that obtain energy by breaking down the remains of dead organisms are called decomposers. They protect the environment from disease by feeding on dead organisms. Decomposers are important for the ecosystem as they help in recycling nutrients. 

Fig 7

Worm          Mushroom    Insects       Bacteria 


This material adds nutrients to the soil that help plants to grow well. There are many types of decomposers. For example, earthworms break down plants only. Organisms like fungi break down rotting wood and other plant parts. 

Fig 8


Organisms that eat rotting animal matter and get rid of it as waste are called scavengers. This helps decomposers break down matter faster. They are also known as scavengers of the ecosystem, e.g., vultures, hyenas, etc. 

Fig 9


  1. Allliving organisms need energy. Energy is the ability to do work.
  2. A food chain shows how energy passes from one organism to another as food. In an ecosystem, animals can be of three types based on their food type: Herbivore, carnivore, and omnivore.
  3. In the food chain, organisms can be classified into producers, consumers, and decomposers.
  4. Producers: Make their own food by using simple components from the surroundings.
  5. Consumers: Depend on producers for the food.
  6. Decomposers: Feed on dead matter and clean the environment.


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