Understanding Taxonomy: The Classification of Living Organisms

Learning Objectives:

· Learns the importance of the living world and its diversity

· Understands the need for classification

· Creates an interest in systematics and understands the importance of taxonomy for classification of animals

· Knows the key rules of nomenclatures and their uses

All living forms co-exist with each other. There are about eight point seven million Eukaryotic species of organisms have been estimated to exist on earth. A study reports that eighty-six percent of all species on the land and ninety-one percent of those in the seas are yet to be discovered, described and catalogued. Though humans are placed in the top most position on the hierarchy, they have to depend on plants and animals for food. Animals are also used as a source of labour, in farming, as pets, and for other economic benefits. Understanding animals and their unique characteristics, habitats, behavior and evolutionary relationships is very important. This chapter deals with, diversity in the living world, need for classification, types of classification, taxonomical hierarchy, nomenclature and tools for studying taxonomy.

One point one. Diversity in the Living World

Earth has numerous habitats with a wide range of living organisms inhabiting them. Plants and animals are present in almost all the places, from polar icecaps to volcanic hot springs, from shallow lagoons to the deepest oceans, from tropical rain forests to dry and parched deserts. There are a variety of species that have been adapted successfully to live in diverse ecosystems. Ecosystem is a community of biotic and abiotic factors and their interrelationships. The presence of a large number of species in a particular ecosystem is called 'biological diversity' or in short 'biodiversity'. The term biodiversity was first introduced by Walter Rosen, and defined by E.D. Wilson.