Haptophyte

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Haptophytes
Coccolithus pelagicus.jpg
Coccolithophore (Coccolithus pelagicus)
Scientific classification (incertae sedis within Eukaryota)
Domain: Eukaryota
(unranked): Diaphoretickes
(unranked): Haptophyta
Hibberd 1976 sensu Ruggerio et al. 2015
Classes & Orders
Synonyms
  • Prymnesiophyta Green & Jordan, 1994
  • Prymnesiophyceae s.l. Casper, 1972, ex Hibberd, 1976
  • Haptophyceae s.l. Christensen, 1962 ex Silva, 1980
  • Haptophytina Cavalier-Smith 2015

The haptophytes, classified either as the Haptophyta, Haptophytina or Prymnesiophyta (named for Prymnesium), are a clade of algae.

The names Haptophyceae or Prymnesiophyceae are sometimes used instead.[1][2][3] This ending implies classification at the class rank rather than as a division. Although the phylogenetics of this group has become much better understood in recent years, there remains some dispute over which rank is most appropriate.

Characteristics[edit]

Cell scheme. 1-haptonema, 2-flagella, 3-mitochondrion, 4-Golgi apparatus, 5-nucleus, 6-scales, 7-crysolaminaran vacuole, 8-plastid, 9-ribosomes, 10-stigma, 11-endoplasmic reticulum, 12-chloroplast endoplasmic reticulum, 13-pyrenoid, 14-thylakoids.

The chloroplasts are pigmented similarly to those of the heterokonts,[4] but the structure of the rest of the cell is different, so it may be that they are a separate line whose chloroplasts are derived from similar red algal endosymbionts.

The cells typically have two slightly unequal flagella, both of which are smooth, and a unique organelle called a haptonema, which is superficially similar to a flagellum but differs in the arrangement of microtubules and in its use. The name comes from the Greek hapsis, touch, and nema, thread. The mitochondria have tubular cristae.

Economic importance[edit]

Haptophytes are economically important as Pavlova lutheri and Isochrysis sp. are widely used in the aquaculture industries.

Examples and classification[edit]

Further information: Wikispecies:Haptophyta

The haptophytes were first placed in the class Chrysophyceae (golden algae) but ultrastructural data have provided evidence to classify them separately.[5] The best-known haptophytes are coccolithophores, which have an exoskeleton of calcareous plates called coccoliths. Coccolithophores are some of the most abundant marine phytoplankton, especially in the open ocean and are extremely abundant as microfossils. Other planktonic haptophytes of note include Chrysochromulina and Prymnesium, which periodically form toxic marine algal blooms, and Phaeocystis blooms of which can produce unpleasant foam which often accumulates on beaches. Both molecular and morphological evidence supports their division into five orders; coccolithophores make up the Isochrysidales and Coccolithales. Very small (2-3μm) uncultured pico-prymnesiophytes are ecologically important[6]

Haptophytes was discussed to be closely related to cryptomonads.[7]

Haptophytes are closely related to the SAR clade.[8]

Subphylum Haptophytina Cavalier-Smith 2015 [Haptophyta Hibberd 1976 sensu Ruggerio et al. 2015][9]

References[edit]

  1. ^ "www.ncbi.nlm.nih.gov". 
  2. ^ Satoh M, Iwamoto K, Suzuki I, Shiraiwa Y (2009). "Cold stress stimulates intracellular calcification by the coccolithophore, Emiliania huxleyi (Haptophyceae) under phosphate-deficient conditions". Mar. Biotechnol. 11 (3): 327–33. doi:10.1007/s10126-008-9147-0. PMID 18830665. 
  3. ^ "ITIS Standard Report". Retrieved 19 July 2014. 
  4. ^ Anderson, R.A. (2004). "Biology and Systematics of Heterokont and Haptophyte Algae". American Journal of Botany. 91 (10): 1508–1522. 
  5. ^ "Phylogenetic relationships of the 'golden algae' (haptophytes, heterokont chromophytes) and their plastids". Plant Systematics and Evolution: 187–219. doi:10.1007/978-3-7091-6542-3_11. 
  6. ^ Cuvelier, M.; Allen, A.; Monier, A.; McCrow, J.; Messié, M.; Tringe, S.; Woyke, T.; Welsh, R.; Ishoey, T.; Lee, J. -H.; Binder, B. J.; Dupont, C. L.; Latasa, M.; Guigand, C.; Buck, K. R.; Hilton, J.; Thiagarajan, M.; Caler, E.; Read, B.; Lasken, R. S.; Chavez, F. P.; Worden, A. Z. (2010). "Targeted metagenomics and ecology of globally important uncultured eukaryotic phytoplankton". Proceedings of the National Academy of Sciences of the United States of America. 107 (33): 14679–14684. Bibcode:2010PNAS..10714679C. doi:10.1073/pnas.1001665107. PMC 2930470Freely accessible. PMID 20668244. 
  7. ^ Reeb VC, Peglar MT, Yoon HS, et al. (April 2009). "Interrelationships of chromalveolates within a broadly sampled tree of photosynthetic protists". Mol. Phylogenet. Evol. 53 (1): 202–11. doi:10.1016/j.ympev.2009.04.012. PMID 19398025. 
  8. ^ Parfrey, Laura Wegener; Lahr, Daniel J. G.; Knoll, Andrew H.; Katz, Laura A. (2011-08-16). "Estimating the timing of early eukaryotic diversification with multigene molecular clocks". Proceedings of the National Academy of Sciences. 108 (33): 13624–13629. doi:10.1073/pnas.1110633108. ISSN 0027-8424. PMC 3158185Freely accessible. PMID 21810989. 
  9. ^ M.D. Guiry (2016), AlgaeBase, World-wide electronic publication, National University of Ireland, Galway, retrieved 25 October 2016 

External links[edit]