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A protist (/ ˈ p r oʊ t ɪ s t / PROH-tist) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus.Protists do not form a natural group, or clade, but are a polyphyletic grouping of several independent clades that evolved from the last eukaryotic common ancestor.
Combined with the five-kingdom model, this created a six-kingdom model, where the kingdom Monera is replaced by the kingdoms Bacteria and Archaea. [16] This six-kingdom model is commonly used in recent US high school biology textbooks, but has received criticism for compromising the current scientific consensus. [ 13 ]
A protist (/ ˈ p r oʊ t ɪ s t /) is any eukaryotic organism (one with cells containing a nucleus) that is not an animal, plant, or fungus.The protists do not form a natural group, or clade, since they exclude certain eukaryotes with whom they share a common ancestor; [a] but, like algae or invertebrates, the grouping is used for convenience.
Kingdom Protista (or Protoctista) is included in the traditional five- or six-kingdom model, where it can be defined as containing all eukaryotes that are not plants, animals, or fungi. [ 16 ] : 120 Protista is a paraphyletic taxon, [ 47 ] which is less acceptable to present-day biologists than in the past.
In 1818, the German biologist Georg A. Goldfuss coined the word Protozoa to refer to organisms such as ciliates, [57] and this group was expanded until Ernst Haeckel made it a kingdom encompassing all single-celled eukaryotes, the Protista, in 1866. [58] [59] [60] The eukaryotes thus came to be seen as four kingdoms: Kingdom Protista; Kingdom ...
A variety of multi-kingdom systems were proposed, and the Kingdoms Protista and Protoctista became established in biology texts and curricula. [ 22 ] [ 23 ] [ 24 ] By 1954, Protozoa were classified as "unicellular animals", as distinct from the "Protophyta", single-celled photosynthetic algae, which were considered primitive plants. [ 25 ]
Protistology is a scientific discipline devoted to the study of protists, a highly diverse group of eukaryotic organisms. All eukaryotes apart from animals, plants and fungi are considered protists. [1]
Systematists today do not treat Protista as a formal taxon, but the term "protist" is still commonly used for convenience in two ways. [22] The most popular contemporary definition is a phylogenetic one, that identifies a paraphyletic group: [23] a protist is any eukaryote that is not an animal, (land) plant, or (true) fungus; this definition [24] excludes many unicellular groups, like the ...