Haptophyte
From Free net encyclopedia
{{Taxobox
| color = khaki
| name = Haptophytes
| image = Emiliania huxleyi 3.jpg
| image_width = 250px
| image_caption = Coccolithophore (Emiliania huxleyi)
| regnum = Protista (Chromalveolata)
| phylum = Haptophyta
| subdivision_ranks = Orders
| subdivision =
Class Pavlovophyceae
Pavlovales
Class Prymnesiophyceae
Prymnesiales
Phaeocystales
Isochrysidales
Coccolithales
}}
The haptophytes, classed either as the Prymnesiophyta or Haptophyta, are a group of algae. The chloroplasts are pigmented similarly to those of the heterokonts, such as golden algae, 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 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.
Most haptophytes are coccolithophores, which are ornamented with calcified scales called coccoliths, and are sometimes found as microfossils. Other planktonic haptophytes of note include Chrysochromulina and Prymnesium, periodically form toxic marine algal blooms. Both molecular and morphological evidence supports their division into five orders; coccolithophores make up the Isochrysidales and Coccolithales.de:Haptophyta fr:Haptophyta nds:Haptophyta