Food chain a food chain is formed by a series of organisms arranged in a linear manner based on their feedings habits. In this chain, each type of organism feeds on the type below it in the series. With this repeated eating and being eaten, there is a transfer of energy from the lower level to the higher level. Each level is therefore, called trophic level. The organism at the lowest level is plant which is called producer, because it prepares food from CO2 H2O and sunlight. Organisms at higher level are called consumers, because they consume the food in rearranged form, originally produced in plants.
Food Web In an ecosystem, there are a number of liners series of food chains. This is because of the variety of organisms and their different food habits. This is the reason why different food chains become interlinked with each other at different points, forming some sort of interlocking pattern. This pattern is called food web.
In the food webs, one population of an animal is consumed by a number of predators which in turn are consumed by many other predators. A more complicated food web reflects a greater balance of the habitat. In other words, in a food web, an organism of a particular trophic level gets its food from more than one trophic level or food chain. If tigers increase in their number in a forest, they will consume more deer. This will decrease the number of deer and the tigers might suffer from starvation due to shortage of their food supply. When the number of tigers reduces, fewer deer will be killed and their population would again increase in due course. This is one of the examples to explain the natural balance operating in any ecosystem.
You might have seen many ponds fully covered by water hyacinth (Eichhornia) on the sides of railway track. It is a free floating aquatic plant which grows vigorously in stagnant bodies of water like ponds and lakes. It covers the entire surface of the aquatic system and derives most of its nutrients from water. It grows and spreads so densely that other photosynthetic plants of the habitat are deprived of sunlight. As a result of this, all other life forms in that habitat gradually die due to lack of food and oxygen. Such ponds are known as dead ponds. This is an example of improper balance. A few years ago the beautiful Hussain Sagar lake of Hyderabad had similar situation. This lake become suitable for the survival of other organisms only after the removal of water hyacinth mechanically and biologically. When such remedial measures are taken to restore a condition wherein other life forms can also exist, we say that the pond or lake has become alive again.