Which realm do viruses belong to

Viruses do not belong to the five kingdom division system proposed by R.H. Whittaker.

In 1967 R.H. Whittaker proposed the five kingdom division system. He first divided organisms into two categories, prokaryotes and eukaryotes, based on the presence or absence of nuclear membrane structure.

Prokaryotes are one kingdom.

Eukaryotes were further divided according to the number of cells, and certain organisms consisting of single cells or groups of single cells (clumps of algae) were categorized into the Protista. The remaining multicellular eukaryotes are further divided according to their trophic type into the Plantae (Plantae); Fungi (Fungi); and Animalia (Animals).

While viruses are a non-cellular life form that consists of a long chain of nucleic acids and a protein shell, viruses do not have their own metabolic machinery and do not have an enzyme system. Therefore it is not attributed to the five realm subsystem.

Because the original five-boundary classification system failed to give a definition for viruses, in the 1970s our scholar Chen Shichun as well as scholars such as Tromba proposed a six-boundary system, i.e., protists, fungi, plants, animals, prokaryotes, and viruses.

Expanded Information

The two-kingdom system

Proposed by Carl Linnaeus

Classification: Plantae and Animalia

Traditionally, the traditional classification considered the kingdoms to be the highest level of classification unit. In Linnaeus' time, he proposed a two kingdom system, the plant kingdom and the animal kingdom, based on the criterion of whether organisms could move, and categorized bacteria, fungi, and so on, in the plant kingdom.

Three realm system

Proposed by Hecker

Classification: protists, plants and animals

Before and after the 19th century, due to the invention and use of the microscope, it was discovered that many unicellular organisms were intermediate types of organisms that had both animal and plant attributes. For example, nudibranchs and methanogens can live both autotrophically and, in some cases, heterotrophically. As a result, Hecker set up a separate boundary for protists (including bacteria, algae, fungi and protozoa, slime molds, etc.), and proposed a three-boundary system of protists, plants, and animals.

Three-kingdom system

Proposed by Woese

Archeobacteriophage (containing the kingdom of Archaea, including methanotrophic, extremophilic, and extremophilic bacteria), Eubacteriophage (containing the kingdom of eubacteria, including bacteria and cyanobacteria), and Eukaryote (containing the kingdom of Protozoa, Fungi, Plants, and Animals).

Baidu Encyclopedia - Biological Divisions

Baidu Encyclopedia - Biological Viruses