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Euglenozoa
Scientific classification
Domain: Eukarya
Kingdom: Excavata
Phylum: Euglenozoa
Cavalier-Smith, 1981[1]
Classes and unplaced genera

Euglenoidea
Kinetoplastea
Diplonemea
Postgaardi
Calkinsia

The Euglenozoa are a large group of flagellate protozoa. They include a variety of common free-living species, as well as a few important parasites, some of which infect humans. There are two main subgroups, the euglenids and kinetoplastids. Euglenozoa are unicellular, mostly around 15-40 µm in size, although some euglenids get up to 500 µm long.

Contents

Structure

Most euglenozoa have two flagella, which are inserted parallel to one another in an apical or subapical pocket. In some these are associated with a cytostome or mouth, used to ingest bacteria or other small organisms. This is supported by one of three sets of microtubules that arise from the flagellar bases; the other two support the dorsal and ventral surfaces of the cell.[2]

Some other euglenozoa feed through the absorption, and many euglenids possess chloroplasts and so obtain energy through photosynthesis. These chloroplasts are surrounded by three membranes and contain chlorophylls a and b, along with other pigments[1], so are probably derived from a captured green alga. Reproduction occurs exclusively through cell division. During mitosis, the nuclear membrane remains intact, and the spindle microtubules form inside of it.[2]

The group is characterized by the ultrastructure of the flagella. In addition to the normal supporting microtubules or axoneme, each contains a rod (called paraxonemal), which has a tubular structure in one flagellum and a latticed structure in the other. Based on this, two smaller groups have been included here: the diplonemids and Postgaardi.[3]

Classification

The euglenozoa are generally accepted as monophyletic. They are related to Percolozoa; the two share mitochondria with disc-shaped cristae, which only occurs in a few other groups.[4] Both probably belong to a larger group of eukaryotes called the excavates.[5]

References

  1. ^ a b T. Cavalier-Smith (1981). "Eukaryote Kingdoms: Seven or Nine?". BioSystems 14: 461–481. doi:10.1016/0303-2647(81)90050-2.  
  2. ^ a b David J. Patterson (1999). "The Diversity of Eukaryotes". American Naturalist 145: S96–S124.  
  3. ^ Alastair G.B. Simpson (1997). "The Identity and Composition of Euglenozoa". Archiv für Protistenkunde 148: 318–328.  
  4. ^ Baldauf et al. (2000). "A Kingdom-Level Phylogeny of Eukaryotes Based On Combined Protein Data". Science 290: 972–977. doi:10.1126/science.290.5493.972. PMID 11062127.  
  5. ^ Alastair G. Simpson (2003). "Cytoskeletal organization, phylogenetic affinities and systematics in the contentious taxon Excavata (Eukaryota)". International Journal of Systematic and Evolutionary Microbiology 53: 1759–1777. doi:10.1099/ijs.0.02578-0. PMID 14657103.  

External links

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Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Taxonavigation

Main Page
Cladus: Eukaryota
Supergroup: Excavata
Superphylum: Discicristata
Phylum: Euglenozoa
Subphyla: Plicostoma - Saccostoma

References

  • Thomas Cavalier-Smith, The excavate protozoan phyla Metamonada Grassé emend. (Anaeromonadea, Parabasalia, Carpediemonas, Eopharyngia) and Loukozoa emend. (Jakobea, Malawimonas): their evolutionary affinities and new higher taxa, Internat. Journal of Syst. and Evol. Microbiol. 53, 1741-1758 (2003).
  • Thomas Cavalier-Smith, Protist phylogeny and the high-level classification of Protozoa, Europ. J. Protistol. 39, 338-348 (2003).

Alternative classifications

T. Cavalier-Smith (1978).

From The evolutionary origin and phylogeny of microtubules, mitotic spindles and eukaryote flagella.

In empire Eukaryota
Kingdom Euglenoida

  • Phylum Euglenophyta
  • Phylum Kinetoplastida

T. Cavalier-Smith (1981).

From Eukaryotic kingdoms: seven or nine?

In empire Eukaryota
Kingdom Euglenozoa
Phylum Euglenozoa

John O. Corliss (1984)

From The kingdom Protista and its 45 phyla.

In Kingdom Protista
Assemblage "Euglenozoa" named after kingdom Euglenozoa Cavalier-Smith 1981

T. Cavalier-Smith (1993).

From Kingdom Protozoa and its 18 phyla.

In kingdom Protozoa, subkingdom Dictyozoa, branch Bikonta
Infrakingdom Euglenozoa Cavalier-Smith 1981 stat. nov.
Phylum Euglenozoa Cavalier-Smith 1981

T. Cavalier-Smith (1998).

From A revised six-kingdom system of life.

In Kingdom Protozoa, Subkingdom Neozoa, Infrakingdom Discicristata
Phylum Euglenozoa Cavalier-Smith 1981

David J. Patterson (1999)

From The diversity of eukaryotes

In Eukaryotes
Clade Euglenozoa

T. Cavalier-Smith (2002).

From The phagotrophic origin of eukaryotes and phylogenetic classification of Protozoa.

In kingdom Protozoa, subkingdom Gymnomyxa, infrakingdom Excavata, superphylum Discicristata
Phylum Euglenozoa

  • Euglenoids
  • Diplonemids
  • Kinetoplastids
  • Postgaardi

Alastair G. B. Simpson (2003)

From Cytoskeletal organization, phylogenetic affinities and systematics in the contentious taxon Excavata (Eukaryota)

In Excavata
Clade Euglenozoa

Articles

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Wikimedia Commons For more multimedia, look at Euglenozoa on Wikimedia Commons.

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