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The species diversity of protists is severely underestimated by traditional methods that differentiate species based on morphological characteristics. The number of described protist species is very low (ranging from 26,000 [ 35 ] to over 76,000) [ c ] in comparison to the diversity of plants, animals and fungi, which are historically and ...
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.
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]
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 ]
Marine protists are defined by their habitat as protists that live in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. Life originated as marine single-celled prokaryotes (bacteria and archaea) and later evolved into more complex eukaryotes .
The alveolates (meaning "pitted like a honeycomb") [2] are a group of protists, considered a major clade [3] and superphylum [4] within Eukarya. They are currently grouped with the stramenopiles and Rhizaria among the protists with tubulocristate mitochondria into the SAR supergroup .
Amoebozoa is a major taxonomic group containing about 2,400 described species of amoeboid protists, [8] often possessing blunt, fingerlike, lobose pseudopods and tubular mitochondrial cristae. [7] [9] In traditional classification schemes, Amoebozoa is usually ranked as a phylum within either the kingdom Protista [10] or the kingdom Protozoa.
It contains a variety of free-living and symbiotic protists, and includes some important parasites of humans such as Giardia and Trichomonas. [5] Excavates were formerly considered to be included in the now obsolete Protista kingdom. [6]