Euglenozoa
The Euglenozoa are a large phylum of flagellate protists. They are part of the wastebasket taxon known as the Protozoa, which had many obviously different protists.
| Euglenozoa | |
|---|---|
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| Two Euglena | |
Scientific classification 
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| Unrecognized taxon (fix): | Euglenozoa |
| Classes | |
Euglenozoa include a variety of common free-living species, and some important parasites, of which a few infect humans. There are two main subgroups, the Euglenoidea "euglenids" and Kinetoplastea "kinetoplastids".[3] Euglenozoa are unicellular, mostly around 15–40 µm in size, although some euglenids get up to 500 µm long.
Most Euglenozoa have two flagella, parallel to one another in a pocket-like structure. In some there is a cytostome or mouth, used to eat bacteria or other small organisms. This is supported by a microtubule from the flagellar bases; two other tubules support the dorsal and ventral surfaces of the cell.[4]
Some other Euglenozoa feed through absorption, and many euglenids have chloroplasts and so get energy by photosynthesis. These chloroplasts are surrounded by three membranes and contain chlorophylls A and C, and other pigments,[3] so are probably evolved from those of a captured green alga. Reproduction occurs only by cell division. During mitosis, the nuclear membrane remains intact, and the spindle microtubules form inside it.[4]
The group is characterized by the ultrastructure of the flagella. In addition to the normal supporting microtubules, each contains a rod (called paraxonemal), which has a tubular structure in one flagellum and a latticed structure in the other.[5]
Classification
The euglenozoa are generally accepted as monophyletic. They are related to Percolozoa. The two share mitochondria with disk-shaped compartments, which only occurs in a few other groups.[6] Both probably belong to a larger group of eukaryotes called the Excavata.[7] This grouping has been challenged.[8]
References
- ↑ Zakryś, B. Euglena: Biochemistry, Cell and Molecular Biology. Advances in Experimental Medicine and Biology 979 (2017). p. 3–17. ISBN 978-3-319-54908-8. doi:10.1007/978-3-319-54910-1_1.
- ↑ Eukaryote kingdoms: seven or nine?. Bio Systems 14 (3–4) (1981). p. 461–481. doi:10.1016/0303-2647(81)90050-2.
- ↑ 3.0 3.1 Cavalier-Smith T. 1981.. Eukaryote kingdoms: seven or nine?. BioSystems 14 (3–4) (1981). p. 461–481. doi:10.1016/0303-2647(81)90050-2.
- ↑ 4.0 4.1 Patterson, David J. 1999.. The diversity of eukaryotes. American Naturalist 154 (S4) (1999). p. S96–S124. doi:10.1086/303287.
- ↑ Simpson A.G.B. 1997.. The identity and composition of Euglenozoa. Archiv für Protistenkunde 148 (3) (1997). p. 318–328. doi:10.1016/S0003-9365(97)80012-7.
- ↑ Baldauf S.L; Roger A.J; Wenk-Siefert I. & Doolittle, W. Ford 2000. A Kingdom-level phylogeny of eukaryotes based on combined protein data. Science 290 (5493): 972–977. [1]
- ↑ Simpson, Alastair G. 2003.. Cytoskeletal organization, phylogenetic affinities and systematics in the contentious taxon Excavata (Eukaryota). International Journal of Systematic and Evolutionary Microbiology 53 (Pt 6) (2003). p. 1759–1777. doi:10.1099/ijs.0.02578-0.
- ↑ Cavalier-Smith T 2009. Kingdoms Protozoa and Chromista and the eozoan root of the eukaryotic tree. Kingdoms Protozoa and Chromista and the eozoan root of the eukaryotic tree. Biol Lett 6 (3) (2010). p. 342–5. doi:10.1098/rsbl.2009.0948. Retrieved 2013-01-22.