The living things like plants and animals constitute the biotic environment.
- The living things are:
- Producers or autotrophs
- Consumers or heterotrophs
- Scavengers, and
Green plants are the only living organisms that make their own food. They are, therefore, called producers. All animals and non-green plants depend on producers for food. All green plants have the pigment called chlorophy11. It helps the plants in producing food by a process called photosynthesis. Since plants make their own food they are called autotrophs.
All animals and non-green plants directly or indirectly depend on plants for food. They consume the food made by the producers. They are called heterotrophs. Therefore, they are called consumers.
Consumers are of three types:
- Herbivorous animals: These are plants-eaters. Since they feed on plants directly, they are called primary consumers.
- Carnivorous animals: These feed on other animals and are called secondary consumers.
- Omnivorous animals: Animals that feed on both plants and animals are called omnivorous animals.
Living organism that feeds on dead animals are called scavengers. When an animal dies, scavengers like flies, crows, vultures and hyaena feed on it. Scavengers help to clean the environment by eating up the bodies of dead animals.
Some bacteria and fungi feed on dead and decaying matter. They break down the dead bodies of plants and animals and release the nutrient substances present in them. This process of breaking down of decaying matter is called decomposition. Decomposers return the nutrients present in decaying matter into the soil. These chemicals are once again picked up from the soil. These chemicals are once again picked up from the soil by plants. From the plants they enter the bodies of consumers and are once again returned to soil after their death. Thus, the nutrients go round and round in a cycle.