Five Kingdom Classification

The five kingdom classification was proposed by Whittaker(1969). Click Lecture link to watch the video lecture on this topic.

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Whittaker proposed five kingdom classification based on the below three characteristics

(a) The complexity of cell: Cell is prokaryote or eukaryote, on this basis, kingdom Monera is formed. And all the prokaryotes are grouped into it.

(b) The complexity of organism: Organism is unicellular or multicellular, on this basis, kingdom Protista was formed, and all the unicellular eukaryotes are grouped into it.

(c) Nutrition: Organism is autotrophic or heterotrophic, on this basis kingdom Fungi, Plantae and Animalia were formed.

Fig. Five kingdom classification

The five kingdom identified by Whittaker are Monera, Protista, Fungi, Plantae, Animalia

Kingdom Monera

The Monera Kingdom consists of unicellular microbial organisms such as bacteria. This kingdom includes bacteria, cyanobacteria, and mycoplasma. We will see more about Monera kingdom in the next chapter.

Kingdom Protista

The kingdom Protista contains unicellular organisms that are aquatic. We will see more about Protista kingdom in the next chapter.

Kingdom Fungi

The kingdom Protista contains multicellular organisms which are decomposers such as mushroom. We will see more about Fungi kingdom in the next chapter.

Kingdom Plantae

The kingdom Plantae consists of all plants and trees. The organisms in this kingdom are mostly producers. We will see more about Plantae kingdom in the next chapter.

Kingdom Animalia

The kingdom Animalia comprises of all animals which can move. The organisms in this kingdom are mostly consumers. They consume what the Plantae kingdom produces. We will see more about Animalia kingdom in the next chapter.

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We know there are different types of organisms living on this planet. These living organisms are quite enormous in number and highly diversified in their characters. The Living organisms have been classified into different groups by different workers Carl Linnaeus, known as the father of classification, classified organisms into two kingdom systems Kingdom Plantae and kingdom Animalia. This system had a number of demerits subsequently, an American taxonomist in 1969 proposed the five kingdom classification.

The organisms in this world are divided into five kingdoms Monera, Protista, Fungi, Plantae, and Animalia. Whittakers five kingdom system is based on five factors complexity of cell, structure complexity of an organism’s body, mode of nutrition, lifestyles and phylogenetic relationships. Let’s understand these five factors one by one the first factor is the complexity of cell structure on the basis of the
nucleus and other characteristics.

Cell Organization

Two types of cells are recognized the first type is a simple primitive cell known as prokaryotic cell as in the case of bacteria and algae the second type of cell is a new chaotic cell which has a complex structure and is found in fungi plants and Animalia

Body Organization Complexity

The second factor is the complexity of an organism’s body the earliest organisms were unit cellular later on complex eukaryotic forms evolved and in due course of time they evolved into multicellular organisms.

Mode of Nutrition

The third factor is the mode of nutrition there are two modes of nutrition autotrophic nutrition and heterotrophic nutrition the process by which organisms synthesize their own food is known as autotrophic nutrition for example plants and certain bacteria in heterotrophic nutrition organisms depend on other organism or plants for their food heterotrophic nutrition is of three main types namely holozoic, saprophytic and parasitic, holozoic mode of nutrition refers to the intake of solid food and breaking it into a simple form in case of saprophytic nutrition organisms obtain their food from dead and decaying organic matter while in case of parasite nutrition organisms depend partially or completely on other organisms for their food causing damage to the host organisms.

LifeStyle of Organism

The fourth factor that was considered while making this five Kingdom system is the lifestyle on the basis of the lifestyles organisms have been put into three groups the first group is that of producers plants which utilize light energy water and carbon dioxide to synthesize their organic food our producers the second group based on lifestyles is that of consumers which are animals that consume either plants or other animals to survive the third group is that of decomposers such as bacteria and fungi which depend on the dead remains of plants and animals for their food and decompose.

Phylogenetic Relationship

The last and the fifth factor is the phylogenetic relationship phylogeny is the evolutionary history of organisms and an index of the true relationship among organisms all kingdoms are arranged to show the probable phylogenetic relationships among them based on fossils and other evidence such arrangement allows us to visualize an increase of complexity with evolutionary time.
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