14-496: 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. 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
28-492: Is a stub . You can help Misplaced Pages by expanding it . SAR supergroup SAR or Harosa is a highly diverse clade of eukaryotes , often considered a supergroup , that includes stramenopiles (heterokonts), alveolates , and rhizarians . It is a node-based taxon , including all descendants of the three groups' last common ancestor, and comprises most of the now-rejected Chromalveolata . Their sister group has been found to be telonemids , with which they make up
42-656: Is likely the most important driver of their brownish-yellow color. 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 , round thread. The mitochondria have tubular cristae . Most haptophytes reportedly produce chrysolaminarin rather than starch as their major storage polysaccharide, but some Pavlovaceae produce paramylon . The chain length of
56-538: Is most appropriate. The chloroplasts are pigmented similarly to those of the heterokonts , 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. Haptophyte chloroplasts contain chlorophylls a , c 1 , and c 2 but lack chlorophyll b . For carotenoids, they have beta- , alpha- , and gamma- carotenes. Like diatoms and brown algae , they have also fucoxanthin , an oxidized isoprenoid derivative that
70-501: The TSAR clade. The name SAR is an acronym derived from the first letters of its three constituent clades; it has been alternatively spelled "RAS". The term "Harosa" (at the subkingdom level) has also been used, with Stramenopiles replaced by its synonym Heterokonta in this variant of the acronym. Before the discovery of the SAR supergroup, stramenopiles and alveolates were classified in
84-541: The aquaculture industry to feed oyster and shrimp larvae. They contain a large amount of polyunsaturated fatty acids such as docosahexaenoic acid (DHA), stearidonic acid and alpha-linolenic acid . Tisochrysis lutea contains betain lipids and phospholipids . The haptophytes were first placed in the class Chrysophyceae (golden algae), but ultrastructural data have provided evidence to classify them separately. Both molecular and morphological evidence supports their division into five orders; coccolithophores make up
98-591: The species Prymnesium parvum . The genus is a unicellular motile alga. It is ellipsoidal in shape one flagellum is straight and there are two longer ones which enable movement. The name Latinizes the Greek prymnēsion ‘cable (for mooring )’, from prymna ‘stern’, from prymnos ‘hindmost’. Prymnesium was likely first recognized and drawn (although not named as such) on July 1, 1920, and then (seemingly independently) officially named shortly afterwards on July 6, 1920. The taxonomy of Prymnesiales
112-524: The Isochrysidales and Coccolithales. Very small (2-3μm) uncultured pico-prymnesiophytes are ecologically important. Haptophytes was discussed to be closely related to cryptomonads . Haptophytes are closely related to the SAR clade. Subphylum Haptophytina Cavalier-Smith 2015 [Haptophyta Hibberd 1976 sensu Ruggerio et al. 2015 ] Prymnesium Prymnesium is a genus of haptophytes , including
126-433: The chrysolaminarin is reportedly short (polymers of 20–50 glycosides, unlike the 300+ of comparable amylose ), and it is located in cytoplasmic membrane-bound vacuoles. The best-known haptophytes are coccolithophores , which make up 673 of the 762 described haptophyte species, and have an exoskeleton of calcareous plates called coccoliths . Coccolithophores are some of the most abundant marine phytoplankton , especially in
140-670: The clade Hacrobia to accommodate them. The SAR supergroup encompasses a variety of morphologies and ecological niches, from microscopic zoo - and phytoplankton to massive kelp forests . The group includes both photosynthetic and non-photosynthetic forms. Photosynthesis arose independently across various stramenopiles and alveolates lineages through secondary or higher-order endosymbiosis events, acquiring plastids of red algal origin, while chlorarachniophyte rhizarians captured plastids from green algae , retaining vestigial nucleomorphs . It has been estimated that SAR encompasses up to half of all eukaryotic diversity. Owing to
154-475: The clade's discovery through phylogenomics , there are no known synapomorphies uniting its various members. This was already the case for its subclade Rhizaria, established earlier through similar means. On the other hand, Stramenopiles is well-defined morphologically, characterized by an anterior flagellum with tripartite bristles ( mastigonemes ), while Alveolata is united by the presence of cortical alveoli . Nonetheless, studies of telonemids , believed to be
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#1732851910200168-449: The open ocean, and are extremely abundant as microfossils, forming chalk deposits. 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. Haptophytes are economically important, as species such as Pavlova lutheri and Isochrysis sp. are widely used in
182-694: The supergroup Chromalveolata alongside haptophytes and cryptomonads , being believed to have acquired plastids through secondary endosymbiosis of red algae through a common ancestor. Meanwhile, Rhizaria was traditionally considered to be a separate supergroup. More recent phylogenetic studies confirmed that stramenopiles and alveolates diverged with rhizarians as part of the SAR lineage. This clade has been found by later phylogenomic studies to be robustly characterized compared to other supergroups. This groups excludes haptophytes and cryptomonads, hypothesized to have acquired plastids in separate endosymbiosis events, leading Okamoto et al. (2009) to propose
196-439: Was revised in 2011. With this revision, ten additional species were added to the genus, namely P. neolepis (previously assigned to Hyalolithus ), P. palpebrale , P. polylepis , P. kappa , P. chiton , P. minus (previously assigned to Chrysochromulina ), P. neustophilum , P. pienaarii , P. pigrum , and P. simplex (previously assigned to Platychrysis ). This haptophyte -related article
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