The ‘food chain’ is defined as the sequence of energy transfer from organism to organism in the form of food. The chain begins with green plants when they make their own food from water, chemicals in the soil and air, and sunlight. Plants are the primary food source. There are many food chains in an eco-system. In a simple food chain, an herbivorous (plant-eating) animal is eaten by a larger carnivorous (flesh-eating) animal. Each of the links in the chain is called a tropic level. The chains do not normally extend beyond four or five atrophic levels. A common example of a simple food chain is the grass-cow-human chain. An example of an ocean food chain is: plankton-snail-small fish-large fish-shark. In a parasite chain, a smaller organism consumes a part of a larger host, and may it be parasitized by even smaller organisms.
Every living thing has its place in one or more food chains. Though plants make their own food, animals cannot do so and depend on others (plants or animals) for their food. Since most of the chains are interconnected, they are called a food web. There are some animals that feed and survive only on one kind of food. If that one source is eliminated, the concerned animals will die. This will break the food chain and may cause many environmental problems.
In a food chain, energy is lost in the form of heat at each step or tropic level. Therefore bypassing one step would add to the energy gains. In the over-populated areas, people commonly increase the total food supply by cutting out a step in the food chain. Instead of eating goats that eat plants, the people themselves eat plants. As the food chain is made shorter, the total amount of energy available to the final consumers in increased.
