All organisms need energy to live. Energy is obtained from food. Green plants are the only organisms that can capture energy from sunlight and make their own food. In this lesson we are going to talk about Food Chains and Food Webs in the environment.
E.g. – Grass (Producer)
All animals depend on plants directly or indirectly for food and energy.
The green plants are the food of all herbivores that are primary consumers.
The herbivores are the food for carnivores that are secondary, tertiary or quaternary consumers.
Secondary consumers are the food for carnivores or top predators that are tertiary or quaternary consumers.
Sometimes tertiary consumers can be the food for quaternary consumers.
Likewise, step by step, the energy in food flows from the producers to consumers.
When an organism dies, it is eventually eaten by scavengers like crows, vultures, worms and crabs and broken down by decomposers (mostly bacteria and fungi), and the exchange of energy continues in the environment.
A food chain is a flow of energy from a green plant (producer) to an animal (consumer) and to another animal (another consumer) and so on.
1) A food chain shows us a series of living things that depend on each other for food energy.
2) A food chain shows us the relationship between the animals and plants in a habitat.
3) A food chain shows us the way energy flows through a habitat.
1) Food chains are usually made of three or four organisms :
Each of these organisms in a food chain is called a link. These links make a food chain.
2) Food chains usually start with a producer or a green plant :
This is the link where energy from the sun enters the food chain.
In nature the food chains are not as direct as we’ve seen them in our discussion. The food chains are highly cross linked (connected) and highly complicated. In any habitat there may be many kinds of animals that feed on the same plants and there may be many predators that feed on the same kinds of prey. Therefore there will be several food chains in any habitat. These food chains are inter-linked and they form food networks in the habitat.
A type of a food network with several inter-linked food chains in a habitat is called a food web.
January 1, 2015