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The Protozoa in this scheme were paraphyletic, because it excluded some descendants of Protozoa. [ 10 ] The continued use by some of the 'Protozoa' in its old sense [ 30 ] highlights the uncertainty as to what is meant by the word 'Protozoa', the need for disambiguating statements such as "in the sense intended by Goldfuß", and the problems ...
A typical example of a ciliated microorganism is the Paramecium, a one-celled, ciliated protozoan covered by thousands of cilia. The cilia beating together allow the Paramecium to propel through the water at speeds of 500 micrometers per second.
The British protozoologist Thomas Cavalier-Smith, since 1998, developed a six-kingdom model: [g] Bacteria, Animalia, Plantae, Fungi, Protozoa and Chromista. [11] [206] In his context, paraphyletic groups take preference over clades: [11] both protist kingdoms Protozoa and Chromista contain paraphyletic phyla such as Apusozoa, Eolouka or ...
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.
Apicomplexa – parasitic and secondary non-photosynthetic protozoa that lack axonemal locomotive structures except in gametes The Acavomonidia and Colponemidia were previously grouped together as colponemids, a taxon now split because each has a distinctive organization or ultrastructural identity .
The characteristics of phylum sarcomastigophora are : (1) Nucleus is of one type except in the stages of certain foraminifera. (2) Locomotory organ either pseudopodia or flagella or both. (3) Reproduction asexual, but when sexually it is essentially by syngamy. Example : Amoeba, Euglena etc.
[31] [32] For some time microsporidia were considered as very primitive eukaryotes, placed in the protozoan group Cnidospora. [5] Later, especially because of the lack of mitochondria, they were placed along with the other Protozoa such as diplomonads , parabasalids and archamoebae in the protozoan -group Archezoa . [ 33 ]
Amoebozoa vary greatly in size. Some are only 10–20 μm in diameter, while others are among the largest protozoa. The well-known species Amoeba proteus, which may reach 800 μm in length, is often studied in schools and laboratories as a representative cell or model organism, partly because of its convenient size.