Classification of Living beings

 

Introduction

                Out earth is populated by a diversity of living organisms including both plants and animals. It is notable that about 500,000 plant species and 1500,000 animal species have already been identified and every year some new species are discovered. Some of these show similar characters while others show different characters. The task of studying the large variety of organisms is made much easier by sorting out properly classifying them into groups and sub-groups.

                The modern theory now commonly applied, is the work  

of Swedish scientist Carolus  Linneaus (1707-1778) who had worked it out, more than two hundred years ago. He used seven major categories in his classification. Out of these, kingdom is the main division. Each kingdom is sub-division into group called phyla (singular-phylum). These are further divided into classes and orders, which consists of families. Families consist of genera (singular-genus), which include various species.

                The system of using the above classification is called the “Binomial system of Nomenclature”; ‘binomial ‘referring to the two aspects: one being the generic name and the other, the specific name. A species is a group of individuals i.e., plants or animals, resembling one other in almost all characters and differing only in minor ones. For example, different types of human being are of the same species. However, man and the closely related monkeys are of different species. A genus is a group related species. The genus “Felis “ include all “true” cats like lion, tiger, domesticated cat, etc. all of these, however, belong to different species, respective of their characters. The generic name is written with its first letter in capital and the specific name with small letter.

 

Example

                Edible pea is designated as Pisum sativum.

                Man is designated as Homo sapiens.

To summaries it all, let us classify man and the domestic cats.

                 

                                         Man                                       Cat

 Kingdom            Animalia                             Animalia              

           Phylum             Chordata                              Chordata

Sub phylum       Vertebrate                            Vertebrate        

          Class                 Mammalia                            Mammalia

Order                 Primates                              Carnivora

Family               Homonidae                           Felidae

Genus                Homo                                    Felis

         

Classification relies on more than one fact. In some cases, through there is a difference in the outer appearance, structure and behavior, they are kept in the same group. Butterfly and bee are different in their size, shape and appearance, but both are kept in the group ‘insecta’ as they have other strong points in common, i.e. both of them have hard coating, six legs and two pairs of wings.