WHITTAKER CLASSIFICATION OF LIVING THINGS (5 KINGDOMS) - BIOLOGY - 2024

The classification of Whittaker divide living things in Monera, Protista, Mycota (Fungi), the kingdom Metaphyta (Plantae) and the kingdom Metazoa (Animals) kingdoms. Although this model is still widely used today, many experts and scientists consider it to be out of date.

In 1969, Robert H. Whittaker proposed a classification of organisms into five kingdoms. This classification has survived to this day. However, some modifications have been made to make it more successful.

The 5 kingdoms of nature

The Monera kingdom is composed of primitive, microscopic, and single-celled organisms. These organisms are made up of prokaryotic cells. Some examples are bacteria and archaebacteria. Currently this kingdom has been divided into two groups: the Archaebacteria kingdom and the Eubacteria kingdom.

The Protista kingdom is composed of eukaryotic single-celled organisms. It includes unicellular algae and protozoa such as amoebas.

The Mycota kingdom is made up of organisms that create networks called mycelium. These organisms can be saprophytes, parasites, or symbionts. Today, this group is known as the Fungi kingdom.

The Metaphyta kingdom comprises multicellular eukaryotic organisms. These organisms are autotrophs, since they synthesize their own food through photosynthesis. Today, this kingdom is called Plantae.

Finally, the Metazoa kingdom is composed of multicellular eukaryotic organisms. Unlike the previous group, these individuals are not capable of producing their own food, so they are heterotrophs. Currently, this is the Animalia kingdom.

The Five Kingdoms of Whittaker

In 1957, Robert Whittaker began to develop his classification system. Initially, he organized individuals into a three-kingdom system, challenging the traditional plant-animal dichotomy.

This classification was based on the trophic levels of nature. In this way, Whittaker grouped organisms into producers (plants), consumers (animals), and decomposers (fungi and bacteria).

A short time later, he added two more kingdoms, completing the system that is currently known.

This pentapartite system attracted the attention of biologists and other scientists because it took into account the fundamental properties of living things: cell structures, number of cells, mode of food, and way of life.

Monera Kingdom

Bacteria

The Monera kingdom was the last kingdom that Whittaker proposed. In this he grouped all prokaryotic unicellular organisms (with cells without nuclei).

The creation of this kingdom was justified thanks to the differences between eukaryotic and prokaryotic organisms.

protist kingdom

Different types of protists

In the Protista kingdom, Whittaker grouped all single-celled eukaryotic organisms. He recognized that the organisms of this realm resembled the organisms of the three higher realms.

However, he justified his decision by pointing out that the difference between unicellular and multicellular was significant enough for unicellular to form a separate kingdom.

Within the Protista kingdom, Whittaker included a subgroup in which bacteria were found.

Mycota Kingdom

For Whittaker, the Mycota kingdom was made up of multicellular eukaryotic organisms.

Before Whittaker, the organisms of the Mycota kingdom were classified as plants. However, the cell of these organisms lacks chloroplasts and chlorophyll, so they are unable to produce food.

Instead, these are heterotrophs and feed by absorbing substances in a state of decomposition or other organic matter present in soils.

The members of this kingdom according to Whittaker were yeasts, molds and fungi.

Kingdom Metaphyta or plantae

Sorghum plant. Pethan assumed (based on copyright claims).. Source: Wikipedia Commons.

In the Metaphyta kingdom, Whittaker grouped eukaryotic organisms, with cell walls and chloroplasts in their cells. The fact of having chloroplasts makes these individuals autotrophs (producers).

Gymnosperms, bryophytes, and ferns were the first individuals to form part of this group.

Later, he included red and brown algae in this kingdom. He justified this decision by stating that in marine ecosystems algae performed the same function as plants in terrestrial ecosystems. For Whittaker, algae were "functional plants."

Kingdom Metazoa or animals

In the Metazoa kingdom, it included eukaryotic organisms with cells without a cell wall and lacking chloroplasts. As they do not present chloroplasts, these organisms are heterotrophs (consumers).

Whittaker classified sponges, invertebrates, and vertebrates under this group.

Value points in the Whittaker ranking

1-Whittaker's classification groups organisms taking into account scientific criteria, derived from the observation of their different characteristics.

2-The Whittaker classification system takes into account:

• The complexity of cell structures: whether it is eukaryotic organisms (with the genetic information contained in a defined nucleus) or prokaryotic organisms (without a nucleus, the genetic information is dispersed in the cytoplasm of the cell).
• The complexity of organisms: whether they are unicellular individuals (made up of a single cell) or multicellular individuals (made up of two or more cells).
• Nutrition mode: if they are autotrophic or heterotrophic.
• Way of life (trophic levels): if they are producers (like plants), consumers (like animals) or decomposers (like fungi).

3- The separation of organisms according to their organization system makes it widely accepted in the scientific world:

• Prokaryotes are part of an independent kingdom, since they are so primitive that they do not resemble the individuals of the other kingdoms.
• Eukaryotic unicellular organisms are grouped in the Protista kingdom, eliminating the complications generated by the similarities between these and plants and animals.
• Fungi are not as primitive as the organisms of the Protista kingdom. They also do not produce their own food like plants. Therefore, it is justified that there is a separate kingdom for these individuals.
• Plants are capable of producing their own food through photosynthesis.
• Animals feed on other organisms, so they are heterotrophs.

Problems with the Whittaker classification

1-Primitive life forms are not organized properly:

• The Monera kingdom and the Protista kingdom include heterogeneous life forms.
• In these two kingdoms are both autotrophic and heterotrophic organisms, organisms with and without cell walls.

2-This system does not propose an adequate classification for viruses or molds.

References

1. Five Kingdom Classification Proposed by RH Whittaker. Retrieved on September 5, 2017, from biologyexams4u.com
2. Hagen, Joel (2012). Five Kingdoms, More or Less: Robert Whittaker and the Broad Classification of Organisms. Retrieved on September 5, 2017, from academic.oup.com
3. Robert Whittaker. Retrieved on September 5, 2017, from wikipedia.org
4. Five Kingdoms Classification. Retrieved on September 5, 2017, from biology.tutorvista.com
5. Classification of Living Organism: Whittaker classification. Retrieved on September 5, 2017, from web-formulas.com
6. Margulis (1971). Whittaker's Fice Kingdoms of Organisms. Retrieved on September 5, 2017, from jstor.org
7. Biological Classification. Retrieved on September 5, 2017, from ncert.nic.in