Five kingdom classification proposed by R.H. Whittaker in 1969. This classification was based upon certain characters like mode of nutrition, thallus organization, cell structure, phylogenetic relationships, and reproduction. This form of kingdom classification includes five kingdoms Monera, Protista, Fungi, Plantae, and Animalia.
The five-kingdom classification of living organisms included the following kingdoms:
The bacteria are categorized underneath the Kingdom Monera.
Features of Monerans
They possess the following important features:
- Bacteria occur everywhere and they are microscopic in nature.
- They possess a cell wall and are prokaryotic.
- The cell wall is formed of amino acids and polysaccharides.
- Bacteria can be heterotrophic and autotrophic.
- The heterotrophic bacteria can be parasitic or saprophytic. The autotrophic bacteria can be chemosynthetic or photosynthetic.
Types of Monerans
Bacteria can be classified into four types based on their shape:
- Coccus: These bacteria are spherical in shape
- Bacillus: They are rod-shaped
- Vibrium: These bacteria are comma-shaped
- Spirillum: This bacteria in spiral-shaped bacteria
Monera has since been divided into Archaebacteria and Eubacteria.
Features of Protista
- They are unicellular and eukaryotic organisms.
- Some of them have cilia or flagella for mobility.
- Sexual reproduction is by a process of cell fusion and zygote formation.
Kingdom Protista is categorized into the following groups:
- Chrysophytes: The golden algae (desmids) and diatoms fall under this group. They are found in marine and freshwater habitats.
- Dinoflagellates: They are usually photosynthetic and marine. The colour they appear is dependent on the key pigments in their cells; they appear red, blue, brown, green or yellow.
- Euglenoids: Most of them live in freshwater habitation in motionless water. The cell wall is absent in them, instead, there is a protein-rich layer called a pellicle.
- Slime Moulds: These are saprophytic. The body moves along putrefying leaves and twigs and nourishes itself on organic material. Under favourable surroundings, they form an accumulation and were called Plasmodial slime moulds.
- Protozoans: They are heterotrophs and survive either as parasites or predators.
The kingdom fungi include moulds, mushroom, yeast etc. They show a variety of applications for domestic as well as commercial purposes.
Features of Kingdom Fungi
- The fungi are filamentous, excluding yeast (single-celled).
- Their figure comprises slender, long thread-like constructions called hyphae. The web of hyphae is called mycelium.
- Some of the hyphae are unbroken tubes that are jam-packed with multinucleated cytoplasm. Such hyphae are labelled Coenocytic hyphae.
- The other type of hyphae has cross-walls or septae.
- The cell wall of fungi is composed of polysaccharides and chitin.
- Most of the fungi are saprophytes and are heterotrophic.
- Some of the symbiont fungi live in association with algae, like lichens. Some symbiont fungi live in association with roots of higher plants, as mycorrhiza.
Features of Kingdom Plantae
- The kingdom Plantae is filled with all eukaryotes which have chloroplast.
- Most of them are autotrophic in nature, but some are heterotrophic as well.
- The Cell wall mainly comprises cellulose.
- Plants have two distinct phases in their lifecycle. These phases alternate with each other. The diploid saprophytic and the haploid gametophytic phase. The lengths of the diploid and haploid phases vary among dissimilar groups of plants. Alternation of Generation is what this phenomenon is called.
Features of Kingdom Animalia
- All multicellular eukaryotes which are heterotrophs and lack cell wall are set aside under this kingdom.
- The animals are directly or indirectly dependent on plants for food. Their mode of nutrition is holozoic. Holozoic nutrition encompasses ingestion of food and then the use of an internal cavity for digestion of food.
- Many of the animals are adept at locomotion.
- They reproduce by sexual mode of reproduction.
The organisms under kingdom Plantae were further classified into photosynthetic and non-photosynthetic, which included Plantae and fungi respectively. This system of classification of living organisms is better than following the older classification of plants and animals because it eradicated the confusion of putting one species in two different kingdoms.