An organism is usually confined to a particular part of a habitat. For example , a caterpillar and an aphid which lice on the same plant occupy different positions or ecological niches on the plant:
• the caterpillar lives mainly on the leaves and feeds on them;
• the aphid lives on the young shoot and sucks sap it.
Although both organisms live in the same habitat, each has its own living space and source of food --- so they can live together as there is no competition between them. Thus, an organism ecological niche is not just the exact place where it lives, it also includes what it does there such as its behavior, feeding habits and breeding habits
Some organisms are specially adapted to live in their niches. For example, the round worm can only live in the intestine of its host; it will not be able to live in any part of its host body, or outside its host body. Its ecological niche is, therefore , restricted to a very specific position in its habitat.
Other organisms are not specifically adapted to a particular ecological niche. The rat, for example , eats all kinds of food, and moves over many habitats. In this case of a toad , the tadpole lives in water, and the adult lives mainly on land. Its ecological niche spans over an aquatic and a terrestrial habitat. A migratory bird such ad the white stork, for instance, nests in Europe in summer (June) and migrates to the grasslands of Africa in winter (December). Thus, its ecological niche ranges over thousands of kilometers.
