Classification of Organism

For things to be quite easy to work with, we need to arrange them in an orderly way. Classification is the sorting of living things into groups according to their common characteristic. The branch of biology concerned with the principle of classification is called taxonomy. Why Classification is important 1.it aids easy identification and study 2.it helps in remembering and understanding 3.it helps scientists in their work How Classification came about •Aristotle (384 – 322): He was one of the earliest taxonomists, a Greek philosopher and biologist. He produced a system of classification based on similarities and differences of organisms. He based his classification of animals on whether they possessed red blood or not and appearance and size as the basis for classification of plants, grouping them into trees, shrubs and herbs. His system of classification was used nearly for 2000 years before it was replaced by another system advocated by Carolus Linnaeus. •Carolus Linnaeus: He was a Swedish naturalist. His system of classification is called natural system because it brings together organisms according to the things they have in common. He classified plants and animals on the basis of their structures, and this system is still in use. According to Linnaeus system of classification, living organisms belongs to seven ranks namely kingdom, phylum, class, order, family, genus, and species. They are in the sequence kingdom –phylum – class – order – family – genus – species. Similarly within the group increases from the top to the bottom. Likeness is well pronounced at the species level and least at the kingdom level. The organisms at the species level are able to make and produce fertile offspring. Mating at the kingdom level is not likely to be possible. Species: it is a group of organisms, which are so much alike in structure and function so that they can interbreed to produce fertile offspring. •John Ray (1677 – 1705): He was a British naturalist who first introduced the concept of species. He defined species as a group of similar individuals that are capable of interbreeding to produce fertile offspring.