Biological classification is a dynamic

C. Linnaeus classified the organisms based on morphological characters like Plantae and Animalia.

But it was not sufficient as there were certain organisms claimed by both botanist and zoologist. Later R.H. Whittaker proposed five kingdom classification system. Euglena and slime moulds were given place under kingdom Protista. Blue-green algae and bacteria were been placed under Monera. In 1977 Carl Woese proposed six kingdom classification. In this classification, the Kingdom Monera was split into two more domains i.e. Eubacteria and Archebacteria this was done based on some major differences in the cell wall. Many more organisms like virus, viroids and prions are there without being classified under any kingdom. Hence it can be said that the biological classification is an ever-evolving phenomenon.