Total numbers of organisms already discovered are about 8.7 millions. Among them 6.5 millions are terrestrial and 2.2 millions are aquatic.The largest group of organisms are arthropods, contains about 75% of the total animal community. Discovery of living organisms every year is a continuous process. Every year almost 15000 new species are discovered. It is estimated that total living organisms including terrestrial, aquatic and aerial are ranges between 5 to 30 million species. We all know that two thirds of entire earth is consists of water. It includes huge oceans, seas, rivers, lakes etc. Many portion of the aquatic area are still undiscovered. As the depth of oceans and some seas are very high and shallow area donot allow sunlight to enter and touch the floor of the sea and oceans. As a result it becomes quite difficult to go there and observe the biosphere. Not only oceans but in some tropical rain forest are also there , where identification and study of different organisms are tough due to adverse weather. About 50 to 100 times more species have been extinct due to bad weather, insufficiency of food, or improper living place. Even according to Darwin’s “survival of the fittest “indicate there is always competition between the two species of same habitants. Winner will be accepted by the nature. Besides this if a community is unable to adjust itself with changes of environment will be extinct automatically in nature.
So, for identification of new and extinct organisms, find connections between different species, discover new species, study there behaviour, study body shape, structure classification is required. As classification is a system of arrangement of organisms into groups on the basis of their similarities, dissimilarities and relationships. It consists of species, genus, family, order, class, phylum and kingdom.
Significance of classifications are:
1. Categorize: classification help an organism to be categorize in its similar community. Suppose prawn, mosquito both have joined legs compound eyes and exoskeleton made up of chitin. So they belong to arthropods (phylum) but some differences between mosquito and prawn locate them in different classes. Mosquito - Insecta and prawn – crustaceans.
2. Study evolution: origin of life on the earth is still a contradict. Classification helps us to study the species and identify their origin.
3. Study of organisms: It is difficult to study all the organisms individually, as we have huge number of organisms in our environment. By studying one of the representatives of different community we are able to come in a conclusion of our study.
4. Identification: Identification of new organism and categorization can be done easily by comparing similarities and dissimilarities with other species.
5. Ecosystem and food chain: By the study of classification we are able to understand the role of different organisms in ecosystem and their importance in food chain.
6. Binomial nomenclature: different organisms are called by their local name. So it is being difficult to establish discussion about the organisms in different state, countries and continent. For this binomial nomenclature has been created according to the units of Classification (kingdom, phylum,class,order,genus, species).As a result an unique name of each species were established (species and genus).