We classify organisms for the following reasons

-To ease the studying of organisms

-To ease communication of information about an organism to the various researchers around the world.

-To avoid confusion among scientists.

-To ease recognition and distinction from many other organisms are that alive.

-To bring out evolutionary relationship between organisms.

-It helps the scientist to make generalization about groups of organisms.

-Biological characteristic of newly discovered species can be predicted.

TAXONOMY HIERARCHIES                                 

This is the arrangement of organisms from the largest group to the smallest groups. These groups are called Taxa (laxon). The largest group is the kingdom and the smallest group is the species.They are 7 major ranges, from the kingdom we go to    the phylum we go to the class from the class we go to the order to family to genius to species. That is kingdom     phylum    class     orders     family     genus      species.

Types of classification

The traditional method of classification places animals into two kingdoms. Those that could move belong to the kingdom animalia and those that were immobile belong to kingdom plantae. Another system of classification of all the unicellular organisms prokaryote and eukaryote into the kingdom protoctista. This then gave 3 kingdoms of classification which are;

1-Kingdom protoctista: made up of unicellular prokaryote and eukaryote

2-Animalia: made up of multicellular heterotrophe animal

3-Plantae: made up of multicellular of autotrophies

Using this scheme is very difficult to place some green algae into a taxonomy categorie. By this scheme all multicellular autotrophes are place in the kingdom plantae. While all multicellular heterotrophe are place under the kingdom animalia by this scheme fungi which are multicellular but are heterotrophe will therefore replace under the kingdom animalia (which is not correct).

 Most recent and most widely classification was discovered and proposed by an American biologist Robert H. Whitaker in 1969. This scheme is base on the five kingdom system. This kingdom includes:

• Kingdom prokaryote (Monera) it include all the prokaryotic organisms usually unicellular and relatively simple in structure e.g. bacteria, blue green algae
• Kingdom protoctista: it include eukaryotic organisms which are unicellular some could be filamentous other colonial and others still simple multicellular organisms e.g.protoalgae
• Kingdom fungi; they are non photo synthesetic, non mobile organisms e.g. mush room, yeust
• Kingdom plantae; this kingdom include all plants which process chlorophyll and which have vascular tissue for transport e.g. ferns, mosses, cornifers
• Kingdom animalia : these are organisms  with no cell walls, no photo synthesis pigment but they show motility e.g. worms, insects, mammals

Bases of Wiltakers classification

He base his classification on two main consideration

1-How the organisms is organized: is the organisms eukaryote if yes it is unicellular or multicellular

2-The mode of nutrition of the organism

Is the organism photosynthetic (those it have chlorophyll) if no it is the organism heterotrophic if yes does it absorb food like in fungi which carryout extra cellular digestion or it injest food like in animal which carryout intra cellular digest; within these classifications organisms like viruses could not be place in a particular kingdom because they are a cellular in nature. Therefore they are studied in part.