Three kingdom classification system

The configuration of organisms into taxonomic groups known as taxa based on similarities or relationships is known as classification. Closely related organisms (those with similar characteristics) are classified as belonging to the same taxon. The similarities and differences between organisms are used to classify them into larger groups. Because the categorization of living organisms is a complex and contentious subject, various taxonomic classification schemes have existed at various times. Linnaeus recognized only two kingdoms of living things in his classification scheme: Animalia and Plantae. Microscopic organisms had not been thoroughly studied at the time. They were either classified as a separate section titled Chaos or, in some cases, as plants or animals.

As understanding of the properties of various groups of microbial life grew, it became clear that a division of the living world into two kingdoms could not be justified on logical and consistent grounds at this level of biological knowledge. Then, in the 1860s, the German researcher Ernst Haeckel proposed a three-kingdom classification system.

The three-kingdom classification

Organisms lacking morphological complexities, a tissue system, division of labor, and a variety of feeding modes were separated and classified as Protista (algae, fungi, protozoa and bacteria).

Organisms with diverse tissue systems, a well-defined division of labor, and the greatest morphological complexities in their body were separated from protists and divided into two categories: those with an autotrophic mode of nutrition were considered plants and placed in the kingdom Plantae, while those with an entirely holophagic (phagotrophic) method of nutrition were considered animals and placed in the kingdom Animalia. According to this system, all known microorganisms were classified as protists; neither plants nor animals were classified as protists.

Kingdom Animalia

We are members of the Class Mammalia, which is part of the Phylum Chordata of the Kingdom Animalia. The Kingdom Animalia is a vast kingdom with numerous species. There were approximately 1.2 million animal species in the animal kingdom. Animals are classified based on their level of organisation, body symmetry, germ layers, coelom nature, segmentation, notochord, and so on.

Phylum Porifera, Hemichordata,  Nematoda, Annelida, Arthropoda, Mollusca, Coelenterata (Cnidaria), Platyhelminthes,  Echinodermata, and Chordata are the different phylum of the Kingdom Animalia. Animalia is distinguished by multicellular, eukaryotic animal forms. Metazoa is another name for it. It is home to approximately 1.2 million animal species ranging from sponges to mammals.

Kingdom Plantae

Plants of various kinds surround us. The leaves, stems, flowers, and fruits of each plant help to identify it. They thrive in a variety of environments. Do you know why they don’t resemble each other? There are many different kinds of plants on the planet, each with its own set of morphological and anatomical characteristics, as well as its own reproductive process. 

All plants in the Kingdom Plantae are classified based on their characteristics. Kingdom Plantae is a large group of plants that are divided into subgroups. It is critical to understand plants, their functions, and characteristics. Continue reading to learn more about Kingdom Plantae.

Kingdom protista

Eukaryotic protists make up the Kingdom Protista. Members of this diverse kingdom are typically unicellular in structure and less complex than other eukaryotes. On the surface, these organisms are frequently described in terms of their similarities to the other groups of eukaryotes: animals, plants, and fungi.

Protists have few commonalities but are clustered together since they do not fit into any of the other kingdoms. Some protists can photosynthesise; some have mutualistic connections with other protists; a few are single celled; some are multicellular or form colonies; some of these are microscopic; some are enormous (giant kelp); some of these are bioluminescent; and some cause a variety of diseases in plants and animals.

Conclusion

Given the foregoing, efforts were made to find a solution, which was proposed in 1866 by E. Haeckel, a German zoologist and Darwin’s disciple. Haeckel proposed that the inconsistencies of the two-kingdom system could be avoided by recognizing a third kingdom, and he proposed Protista as a new kingdom to accommodate organisms with characteristics that are either common to both plants and animals, or unique to them. As a result, the kingdoms Protista, Plantae, and Animalia evolved into a three-kingdom system. Haeckel made this arrangement based on morphological complexities and tissue systems, division of labor, and mode of nutrition.