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How did Robert H. Whittaker’s five-kingdom system classify living organisms?

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A herd of African elephants stands at the edge of the Chobe River in Botswana, drinking water with a backdrop of dry hills and scattered green trees. — life A herd of African elephants (*Loxodonta africana*) drinking from the Chobe River, Botswana.

Robert H. Whittaker’s five-kingdom system, which gained widespread support among biologists in the late 20th century, classified living organisms based on their cellular organization and modes of nutrition. This system divided life into two superkingdoms: the Prokaryota and the Eukaryota.1

The five kingdoms are organized as follows:

Monera: This kingdom constitutes the superkingdom Prokaryota, consisting of organisms that lack a membrane-bound nucleus, such as bacteria.21
Protista: This kingdom includes eukaryotic microorganisms that do not fit into the other three eukaryotic kingdoms.1
Plantae: Comprised of multicellular, photosynthetic organisms that typically possess cell walls.1
Animalia: Comprised of multicellular organisms that are generally motile and ingest their food.1
Fungi: A distinct kingdom of eukaryotic organisms that lack chlorophyll and obtain nutrients through absorption rather than photosynthesis.21

By separating the fungi and the prokaryotic Monera from the traditional plant and animal categories, Whittaker’s system provided a more accurate reflection of the evolutionary and structural diversity of life.1