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Haptophyta Prymnesiophyte algae; Prymnesiophyta; Coccolithophorids

Higher taxa:  Life   Chromalveolata   IDnature guides: Groups_Algae, Groups_Protista We parsed the following live from the Web into this page. Such content is managed by its original site and not cached on Discover Life. Please send feedback and corrections directly to the source. See original regarding copyrights and terms of use. University of Maryland Museum of Paleotology, University of California, Berkeley University of Western Cape, South Africa

Kinds

Amphimonadaceae Braarudosphaeraceae Calciosoleniaceae Calyptrosphaeraceae Ceratolithaceae Coccolithaceae Coccolithophoraceae Derepyxidaceae Gephyrocapsaceae Halopappaceae Helicosphaeraceae Hymenomonadaceae Isochrysidaceae Noelaerhabdaceae Ochrosphaeraceae Papposphaeraceae Pavlovaceae Phaeocystaceae Phaeocytaceae Pontosphaeraceae Prinsiaceae Prymnesiaceae Prymnesiophyceae Rhabdosphaeraceae Syracosphaeraceae Tetragonidiaceae Zygodiscaceae Zygosphaeraceae

Phylogeny

Tree of Life Higher classification of calcareous nannofossils, Natural History Museum, London

Links to other sites

Introduction to the Prymnesiophyta, University of California Museum of Paleontology

Acknowledgements

Ashley MacDonald, University of Georgia, Athens I thank John Pickering for his assistance with the development of this page.

Following modified from University of Maryland

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Haptophyta Introduction Also called the Prymnesiophyceae , or coccolithophorads Coccolithophorad refers to their calcareous scales, called coccoliths, which are important stratigraphic markers Marine unicellular flagellates Zoids (flagellate cells) with wo naked flagella and a haptonema Pigmentation is similar to that seen in some heterokont groups, but plastids seem to have been acquired independently Major players in global phytoplankton, particularly in the open ocean Can be bloom formers Structure & metabolism Typically flagellates Two naked flagella, which may be equal or unequal in length One order, the Pavlovales has delicate hairs ( not mastigonemes) on the flagella Unlike heterokonts, do not have swelling at flagellar base Haptonema is present in most A long, thin structure reminiscent of a flagellum, but with a different ultrastructure 6-7 microtubules in a ring or crescent, with a fold of endoplasmic reticulum extending out within the flagellum In cross section a small number of individual microtubules and three membrane layers are seen Contrast this with the typical eukaryotic 9+2 flagellum, where each of the 9 flagellar rods is composed of three fused microtubules Sometimes with amoeboid, coccoid, palmelloid, or filamentous stages Cell surface is typically covered with external scales, often of more than one type Tiny cellulosic scales Calcified scales -- Coccoliths These can be large, and may be visible with the light microscope Coccoliths fossilize well, and are important stratigraphic markers. The chalk deposits from the Cretaceous are composed largely of coccoliths Coccoliths were known from the fossil record before the living organsims that produce them were identified. Scales are synthesized in the ER, then transported to the surface of the cell A few species lack scales Mitosis - distinctive Open Chromatin plate with channels for pole-to-pole microtubules Chloroplast is secondary, with a CER, but no nucleomorph Thylakoids are stacked in threes There are no girdle lamellae There may be an eyespot in the chloroplast, but there is no associated flagellar swelling Mitochondrial genetic code uses UGA for tryptophan Reproduction Some have a heteromorphic alternation of generations Diploid flagellate alternates with haploid filament Life cycle of others is unclear Classification About 75 genera & 500 species Once classified with the heterokonts on the basis of pigmentation, haptophytes are now thought to have acquired their secondary plastid independent of heterokonts. Haptophytes and heterokonts together all called chromophytes (a reference to their golden pigmentation) Text p. 223 has a good summary of the characters separating haptophytes from heterokonts: Lack of pleuronematic flagella with mastigonemes Presence of haptonema Lack of chloroplast girdle lamellae Distinct structure of golgi apparatus Absence of flagellar swelling Presence of peripheral ER cisternae beneath plasmalemma Arrangement of chloroplast DNA Distinctive pattern of mitosis Pavlovales are probably the outgroup to the rest of the Haptophyta Pavlova gyrans Strongly metabolic , with the cell shape highly variable, it is named for a Russian ballerina Anna Pavlova Prymnesiales Chrysochromulina Isochrysidales Isochrisis Coccolithophorales Emiliana huxleyi - global distribution, bloom former, major player in marine phytoplankton Thought to be largest global producer of calcium carbonate, hence major sink for CO2. Ecology Mostly marine, a few are freshwater From tropics to polar waters. Greatest diversity is in the tropics Major contributors to primary productivity in open ocean May form massive blooms Because the coccoliths reflect light, these are called "whitewater blooms" Most haptophytes are nontoxic, and are considered to have a high food value (for zooplankton) and to be major contributors to marine food web However, a major bloom of Chrysochromulina polylepis near Sweden and Norway was toxic, and had a substantial environmental and economic impact. Economic Importance Form the basis for key marine food webs Ultimately responsible for some major oil deposits Key role in global CO2 balance Formed cretaceous chalk beds Blooms may be toxic Required Reading: VdH Chapter 14 Supplementary Reading: Daugbjerg, N., and R.A. Andersen. 1997. Phylogenetic analysis of the rbcL sequences from haptophytes and heterokont algae suggest their chloroplasts are unrelated. Mol. Biol. Evol. 14:1242-1251. Home Syllabus Gallery Links

Following modified from Museum of Paleotology, University of California, Berkeley

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Introduction to the Prymnesiophyta Coccolithophorids and other Haptophytes Also known as Haptophyta, the Prymnesiophyta includes about 500 living species in 50 genera, with many additonal fossil genera and species, most notably the coccolithophorids . Members of this group are primarily unicellular, and are photosynthetic. They are often important sources of food for aquatic communities. Prymnesiophyte algae are generally marine and are mostly tropical, though there are a few freshwater and terrestrial species reported. The group occurs worldwide, and several species have global distributions. Some prymnesiophytes produce algal blooms which may cause serious problems for fish and for fishermen. Large blooms are problematic because of the mucilage surrounding the algal cells; it may clog fish gills, or render them permeable to dissolved toxins. Another problem is the production of dimethyl sulfide (DMS), a noxious-smelling compound which has been known to cause fish migrations to alter their normal routes. Haptophytes are often a golden-brown color because of the presence of the yellow-brown accessory pigments , diadinoxanthin and fucoxanthin, a feature they share with other Chromista . These are contained in the one or two plastids that are present in the cell. Prymnesiophytes may have a complex life cycle, with an alternation between motile and non- motile phases of different morphologies. The name Haptophyta was originally applied to the group because of the presence of the unique organelle, the haptonema . This is a peg-like structure that extends out from the cell near the point where the two flagella are attached. The haptonema was originally thought to be a third flagellum, but has since been found to have a quite different morphology, and its function is unknown. Many prymnesiophytes are covered with scales, which can have rather complex architecture; they may have spines or an elaborated rim, and come in an amazing variety of shapes -- pentagons, muffin-shapes, baskets, donuts, or even trumpet-like shapes are known. The scales may remain unmineralized, and consist primarily of carbohydrates, or they may be calcified; silica plates are rare. These plates are formed by deposition within the Golgi apparatus , and are often embedded in mucilage. Coccolithophorids are the best known members of the Prymnesiophyta. These delicate-looking organisms have external calcified plates (known as coccoliths ), with a complex ornamentation. Cells may bear only one kind of plate or two. The plates accumulate on the bottom of the ocean as the organisms die, and there contribute to the formation of ocean sediments, carbonate oozes, and rocks such as the Mesozoic limestones and chalks. Fossils of this group date back into the Jurassic , where they first become abundant, and some possible fossils of coccolithophores have been recovered from the Pennsylvanian. The group made a sudden and rapid appearance of new forms in the early Jurassic, and reached its greatest abundance in the Late Cretaceous . Near the end of the Cretaceous, the coccolithophores suffered a mass extinction of groups; two-thirds of the 50 genera disappear at that time, though many new groups appear in the Paleocene. Extensive information on Emiliania huxleyi , a common marine coccolithophore, is available from the Ehux Web Site , including SEM and satellite pictures. Join the Nannofossil List Group ! Pictures of coccolith courtesy Dr. William Ruddiman and the US National Geophysical Data Center.

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