Haptophyta

The Haptophytes , or Haptophyta , are a group of unicellular Algue S (of the group of the Chromalveolata) (they are sometimes called Prymnesiophyta , but this forever validated name), characterized by the presence of a particular appendix different from whip, the haptonème. It is about a thread-like appendix made up of Microtubule S whose size varies according to the species, and who would allow adhesion a substrate, the displacement of particles even the capture of preys the number of current species is estimated at approximately 500. Many species are tropical, some species live out of fresh water and of many fossil groups exist.

This group presents a large variety of forms of life, showing various structural types. One distinguishes from the forms monadoïdes, isolated cells mobile and whipped having two whip, equal or unequal, with the haptonème inserted between them; forms palmelloïdes, motionless colonies included in mucilage; forms coccoïdes, cells only motionless; even mobile forms amoeboïdes, cells thanks to pseudopodes.

At the ultrastructural level, a endoplasmic Réticulum surrounds the cell under the plasmic membrane and another reticulum wraps the core and the Plaste S. In the latter, the Thylakoïde S are assembled by three, without peripheral plate, not forming a grana. The principal pigments are the Chlorophylle S has and C also accompanied by Xanthophylle S, like fucoxanthin. Moreover mitochondries have tubular peaks.

These characters bring closer the Haptophyta to the Heterokontophyta . Those present in more one propeller of transition to flagellar insertion, a peripheral plate of thylakoïdes, and mastigonèmes (tubular hairs) on whip.

The division of the Haptophyta is made up of two quite distinct classes at the ultrastructural level: the Pavlovophyceae and the Prymnesiophyceae. This scission in the group was suggested a long time by many ultrastructural studies, in particular compared to flagellar insertion. More recently, the comparison of sub-unit 18 S.A. reinforced this separation.

whipped, both off which are smooth, and has single organelle called has haptonema , which is superficially similar to has flagellum goal differs in the arrangement off Microtubule S and in its uses. The name comes from the Greek hapsis , touch, and nema , thread. The mitochondria cuts tubular Crista E.

The most haptophytes are the Coccolithophore S, which are ornmmented with calcified scales called Coccolith S, and are sometimes found ace microfossils. Other planktonic haptophytes off note include Chrysochromulina and Prymnesium , periodically form toxic marine Algal bloom S. Both molecular and morphological obviousness supports to their five division into orders; coccolithophores make up the Isochrysidales and Coccolithales.-->

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