Our planet, earth, is occupied by diverse kinds of living organisms. They live in various environments. The world is estimated to have 5 to 30 million species of living organisms. At present about 2.5 million species of living organisms have been given scientific names. Over 1.5 million of them are animal species and out of which 750,000 belong to insect species alone. There are 350,000 species of plants including algae, fungi, mosses and higher forms of plants. Thus the existence of different forms of a species or genus and diverse adaptations for, varied surroundings are referred to as “biodiversity”.