Overview
The Chromista are a supergroup, probably polyphyletic,1][2] which may be treated as a separate kingdom or included among the Protista. They include all algae whose chloroplasts contain chlorophylls a and c, as well as various colorless forms that are closely related to them. These are surrounded by four membranes, and are believed to have been acquired from some red alga.
Groups
There are three different groups:[3]
- Heterokonts or stramenopiles - brown algae, diatoms, water moulds, etc.
- Haptophytes
- Cryptomonads
History and Controversy
The name Chromista was first introduced by Cavalier-Smith in 1981;[4] the earlier names chromophyte and chromobiont correspond to roughly the same group. Molecular trees have had some difficulty resolving relationships between the different groups. All three may share a common ancestor with the alveolates (see chromalveolates), but there is evidence that suggests that the haptophytes and cryptomonads do not belong together with the heterokonts.[5][1]
Photos
Taxonomy
The Kingdom Chromista is a member of the Domain Eukaryota. Here is the complete "parentage" of Chromista:
The Kingdom Chromista is further organized into finer groupings including:
- Subkingdom (2): Chromobiota · Cryptista
- Branch (1): Protostomia
- Infrakingdom (2): Haptista · Heterokonta
- Phylum (10): Cryptista · Cryptophyta · Haptophyta · Hyphochytriomycota · Katablepharidophyta · Labyrinthulomycota · Ochrophyta · Oomycota · Opalozoa · Sarcodina
- Species: ZipcodeZoo has pages for 17,562 species and subspecies in the Kingdom Chromista.
Phyla
Cryptista
Cryptophyta
The cryptomonads (or cryptophytes) are a group of , most of which have chloroplasts. They are common in freshwater, and also occur in marine and brackish habitats. Each cell is around 10-50 µm in size and flattened in shape, with an anterior groove or pocket. At the edge of the pocket there are typically two slightly unequal flagella. [more]
Haptophyta
The haptophytes, classed either as the Prymnesiophyta or Haptophyta, are a of algae. [more]
Hyphochytriomycota
Katablepharidophyta
Labyrinthulomycota
Ochrophyta
Oomycota
Oomycota also known as Water molds (or water moulds: see ) are a group of filamentous, unicellular heterokonts, physically resembling fungi. They are microscopic, absorptive organisms that reproduce both sexually and asexually and are composed of mycelia, or a tube-like vegetative body (all of an organism's mycelia are called its thallus). [more]
Opalozoa
Sarcodina
Amoeboids are life-forms characterized by their irregularity of shape. [more]
At least 1,687 species and subspecies belong to the Phylum Sarcodina.
More info about the Phylum Sarcodina may be found here.
References
- ^ a b Laura Wegener Parfrey, Erika Barbero, Elyse Lasser, Micah Dunthorn, Debashish Bhattacharya, David J Patterson, and Laura A Katz (2006 December). "Evaluating Support for the Current Classification of Eukaryotic Diversity". PLoS Genet. 2 (12): e220. doi:
- ^ Cavalier-Smith T, Allsopp MT, Chao EE (November 1994). "Chimeric conundra: are nucleomorphs and chromists monophy letic or polyphyletic?". Proc. Natl. Acad. Sci. U.S.A. 91 (24): 11368–72. PMID 7972066.
- ^ Csurös M, Rogozin IB, Koonin EV (May 2 008). "Extremely intron-rich genes in the alveolate ancestors inferred with a flexible maximum-likelihood approach". Mol. Biol. Evol. 25 (5): 903–11. doi:
- ^ T. Cavalier-Smith (1981). "Eukaryote kingdoms: seven or nine?". Biosystems 14: 461–481. doi:
- ^ Burki F, Shalchian-Tabrizi K, Minge M, et al (2007). "Phylogenomics reshuffles the eukaryotic supergroups". PLoS ONE 2 (8): e790. doi:
Sources
- The text on this page is licensed under the GNU Free Documentation License. It includes material from Wikipedia retrieved Thursday, August 13, 2009.
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