Foraminifera

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Foraminifera
Ammonia tepida

Ammonia tepida

Systematics
Classification : Creature
Domain : Eukaryotes (eukaryota)
without rank: Sar
without rank: Rhizaria
without rank: Retaria
without rank: Foraminifera
Scientific name
Foraminifera
d'Orbigny , 1826

Foraminifera (Foraminifera), seldom also called chamberlings , are unicellular , mostly shell-bearing protists from the group of Rhizaria . They include around 10,000 recent and 40,000 known fossil species, making them by far the largest group of Rhizaria.

Only around fifty species live in freshwater , all other foraminifera inhabit marine habitats from the coasts to the deep sea. The animals mostly colonize the seabed ( benthos ); a small part, the Globigerinida , lives floating in the water ( planktisch ).

The extraordinarily diverse group has been found in fossils since the Cambrian (around 560 million years ago), but studies of the molecular clock indicate a significantly older age of 690 to 1150 million years. Foraminifera serve in paleontology as reference fossils of the Cretaceous , Paleogene and Neogene due to their fossil-preservable, often rock-forming shells .

features

All types of foraminifera are unicellular organisms that can reach an age of several months or even a few years. The majority of the living species are between 200 and 500 micrometers in size, the smallest representatives measure only up to 40 micrometers ( Rotaliella roscoffensis ) and the largest up to 12 ( Cycloclypeus carpenteri ) or even 20 centimeters ( Acervulina ). Almost all species usually have a multi-chambered housing. Through its perforation, thread-like, very thin cytoplasmic parts can emerge in individual cases. The main mass of these rhizopod pseudopods emerges from the mouth and forms a network with one another, distributed over the entire housing.

casing

The shells of the foraminifera can be built very differently, the diversity of their structure serves as a diagnostic feature for differentiating the taxa . On the one hand, the material and on the other hand the underlying construction plan are relevant.

Housing of foraminifera, off Myanmar

Building material

Based on the building material of their housing , foraminifera can be divided into four groups:

By far the largest group serves secretory excreted calcium carbonate (lime) as a building material, mostly in the form of the unstable vaterite . Later it becomes calcite ( calcite ), very rarely aragonite . For a more precise breakdown, the building material can be further differentiated primarily on the basis of its magnesium content (high / low). In contrast, in agglutinating foraminifera on a mineral or protein basis, grains of sand or other foreign bodies that have been taken up from the sediment stick together. Thus they form a higher form of the purely protein-based (rarely even completely missing) housing of the order of the Allogromiida , into which individual particles from the environment are occasionally taken up.

A special case, on the other hand, is the order Silicoloculinida , which only consists of the genus Miliammellus , in which opal casings are found (SiO 2 xn H 2 O).

Housing benthic foraminifera from the deep sea off Venezuela

Blueprint

The housings can consist of just one chamber (monothalam), a series of interconnected chambers (polythalam) or - very rarely - completely absent (athalam). The dividing walls of the chambers (“ septa ”) are perforated (“foramen”) and allow the protoplasmic body to move within the housing; the opening of the last chamber ("aperture") serves as a gate to the environment.

Multi-chamber housings can be arranged differently. The simplest form is the uniserial construction in which one chamber follows the next. If the chambers form two rows offset from one another, one speaks of biserial housings. Triserial housings, formed from three staggered rows, are also called trochospiral and form a contrast to plane-spiral housings. With the latter, each revolution of the spiral takes place on the same plane as the previous one, so the housing remains flat in the side view. Trochospiral casings, on the other hand, appear in widening, helical spirals with each revolution; its spiral side is bulged and the underside is flattened. Special forms are miliolid housings, in which the spiral is made up of only two elongated tubular chambers, and annular housings, which - similar to annual rings - are circular. In the center of the spirals is the navel, the so-called umbilicus.

The shells of the sand-shelled Textulariida and all calcareous-shell species with the exception of those of the porcelain-shelled Miliolida have pores measuring 1 to 10 micrometers, which are used for gas exchange and the absorption and release of nutrients.

Miniacina miniacea , in situ

cytoplasm

The housings of multi-chambered foraminifera are often only temporarily or partially filled with cytoplasm , and younger chambers in particular often remain empty. The cytoplasm is tough to gelatinous and actually colorless, but is colored in various ways by food or endosymbionts, from whitish to yellowish, greenish, orange, reddish to brownish. The coloration is variable and also depends on the ecological circumstances under which an individual lives or in which phase of his life cycle it is.

There is no clear differentiation into endoplasm and ectoplasm , but the housing is covered by a thin layer of cytoplasm, which also forms the reticulopodia.

Reticulopodia

Like all rhizopoda also have the foraminifera Pseudopodia (pseudopodia). These protuberances from the cytoplasm are used for anchoring in the ground, for locomotion, the uptake of particles for the construction of the housing as well as the collection of nutrients, the catching of prey and occasionally for digestion outside the housing. They are long, thread-like, and thin, tapering at their respective ends to a diameter of less than a micrometer .

In contrast to other pseudopods, the pseudopods of the foraminifera have the ability to anastomose , i.e. they can branch out and merge with other pseudopods. In this way, foraminifera can form a complex network outside of their body that can spread over an area of ​​several hundred square centimeters. In this case one speaks of reticulopodia .

The reticulopodia are solidified by microtubules that occasionally appear individually, but mostly in bundles , which also mediate movements, including a special feature of the foraminifera, a bidirectional flow of the cytoplasm within the reticulopodia. The guiding structure for the so-called “ granule flow” is represented by bundles of microtubules through which mitochondria , dense bodies , encased and elliptical vesicles within the reticulopodia are transported in two directions simultaneously (bidirectional). The phagosomes and defecation vacuoles, which also appear as granules , are only transported unidirectionally.

Life cycle

The life cycles of foraminifera species have only been sparsely researched up to the present; they are only fully known for less than 30 of the approximately 10,000 species. A heterophasic generation change between the sexual, haploid and asexual, diploid generation is typical . This generation change has been modified again evolutionarily in some groups. The two generations are different in shape ( dimorphism ). The variability of the life cycle within the foraminifera, however, is extraordinarily high, and almost every characteristic of the typical life cycle has a different form.

In addition to sexual reproduction, in particular single-chambered foraminifera species can also reproduce asexually, namely via budding , cell division and cytotomy .

Foraminifera ecology

Foraminifera can be divided ecologically into four groups. The distinction between the only fifty or so plankton species and the largest group, the benthic foraminifera that live on the sea floor, is classic . A special group of benthic foraminifera are the approximately fifty large foraminifera found in light-flooded shallow waters. It is only in the last few years that the outlines of a fourth group have emerged, that of the unconnected foraminifera that live in freshwater. Around fifty species of them are known to date. No information can yet be given about the final size of this group.

Shells of benthic foraminifera from North America, (starting clockwise at the top left: Ammonia beccarii , Elphidium excavatum clavatum , Buccella frigida , Eggerella advena , SEM image , different scales)

Benthic foraminifera

The benthic foraminifera are by far the largest group in terms of number of species and comprise around 10,000 species. They can be detected down to the deepest point of the oceans in the 10,900 meter deep Challenger Depth, where they are extremely common elements of the local fauna. On the ground they can be firmly attached to the substrate or wander freely, but the transitions are fluid and the states are often temporary.

For attachment, benthic species require solid substrates, on which they are usually supported by their pseudopodia (e.g. Astrorhiza limicola , Elphidium crispum , Bathysiphon spp.), But also with organic membranes ( Patellina corrugata ), adhesive discs ( Halyphysema ) or sulfuric acid Anchor mucopolysaccharides ( Rosalina spp.). The attachment is often only temporary, in preparation for reproduction e.g. B. the connections are released again. Some species can migrate at speeds of up to 12 centimeters per hour. However, not only rocks or the like serve as substrates, but z. B. also shells of mussels, hydrozoa or brachiopods , where they act as commensals in the food stream. They are found epiphytically in algae or seagrass vegetation , where the detritus that arises forms their food base. On less solid subsoils, they are found as so-called "endobenthic foraminifera" not only on the sediment surface, but also at depths of up to 16 centimeters in the sediment (e.g. Elphidium spp.), Sometimes actively consuming or reproducing.

Species living without light often function as decomposers of detritus, especially those of phytoplanktic origin. Species in the deep sea live on material that has already been decomposed. In addition, there are carnivorous, herbivorous or omnivorous species that feed on pastures, destructors, filter feeders or parasites , for example ; many species specialize in their diet on individual prey groups. The way of life of some of these species is also planktonic at times.

Large foraminifera

“Star sand ,” Hatoma

The special group of large foraminifera, which includes around fifty species, is usually separated from the benthic foraminifera. They are not only characterized by their sometimes extraordinary size of up to 13 centimeters, but above all by their way of life. Large foraminifera occur exclusively in shallow waters from the intertidal zone to around 70, rarely up to 130 meters deep. They accommodate algae (in some cases only their chloroplasts ) as endosymbionts in their translucent housings, through whose photosynthesis they cover their energy needs and lime is used to build the housing. Large foraminifera contribute around 0.5% to global carbonate production. This symbiosis has arisen several times independently of one another and, depending on the family, includes red algae , chlorophytes , dinoflagellates or diatoms as symbionts . The symbionts are found as zoochlorellae or zooxanthellae in the cytoplasm of benthic foraminifera and can occupy up to 75% of the housing volume; According to estimates, their number is over 100,000 in Peneroplis pertusus and around 150,000 in Heterostegina depressa .

Fusulunide large foraminifera

Large foraminifera are purely tropical or subtropical. They reach their highest biodiversity in the Indo-Pacific region. But they can also be found in the Caribbean , the Central Pacific and the Gulf of Aqaba . Representatives can be found in the families Nummulitidae , Amphisteginidae and Calcarinidae of the order Rotaliida , as well as Alveolinidae , Peneroplidae and Soritidae of the order Miliolida . The best-known representatives are the species of the genus Baculogypsina , whose characteristically shaped shells form the so-called “star sand” on the beaches of the Ryukyu Islands. The most common type, however, is Heterostegina depressa .

The existing populations of the large foraminifera are considered relics of much more diverse groups. B. possessed sediment-forming distribution in the Carboniferous and Permian ( Fusulinida ) or in the Tertiary . They usually live in large groups and are so-called K-strategists who use limited resources and whose adequate use only grows slowly and occurs in constant population sizes. Their lifespan is remarkable, which can be several years and cannot be reached by any other single-cell organisms.

Planktonic foraminifera

With less than fifty known species, all of which belong to the order Globigerinida, the proportion of foraminifera living in plankton is low, purely according to the number of species. The fact that planktonic foraminifera, the most important carbonate producers, produce around 20% of the annual amount, however, illustrates their large biomass. They are common in polar to tropical seas, with a particularly large number of species found in subtropical to tropical waters. They are mainly found in water close to the surface between 10 and 50 meters, but also reach depths of up to 800 meters. Many species, like the large foraminifera, harbor photosynthesizing symbionts in the form of the specialized dinoflagellate Gymnodinium beii or golden-brown algae .

Freshwater foraminifera

The classic conception of foraminifera as exclusively marine organisms with shells has been called into question by research results since the turn of the millennium. Although several freshwater species from Lake Geneva were first described as early as the second half of the 19th century , their systematic position was unclear, as was the case with Reticulomyxa filosa, which has been known since 1949 , and they were mostly assigned to groups other than foraminifera. The size of the group, its distribution and way of life were almost unexplored, as late as 2003 Maria Holzmann wrote : "Freshwater foraminifera are one of the most puzzling groups of protists." Molecular biological studies could not only prove that some of them were involved Foraminifera acts, but sequencing environmental samples from different origins has also shown that there are numerous still unknown species. As a résumé of these samples, contrary to previous assumptions, it could be determined that “foraminifera are widespread in freshwater environments”. The first description of a terrestrial species such as Edaphoallogromia australica shows that foraminifera also spread outside of water bodies.

Meaning of the foraminifera

Petrified large foraminifera

Foraminifera are important in paleontology , among other things . Decay-resistant housings can be preserved after the cell has died through fossilization . On the basis of fossil foraminifera associations, one can reconstruct the environmental conditions of past times and relatively date the rocks containing them ( biostratigraphy ). From the Cretaceous onwards , planktonic foraminifera were important key fossils due to their marine way of life and thus almost worldwide distribution . Some fossil forms appeared in such quantities that they became rock-forming, such as the globigerins ( Globigerinida ), the fusulins (Fusulinida) and the nummulites (Nummulitidae). Famous such rocks are the Eocene Nummulite limestone, which was used in the construction of the Egyptian pyramids.

Neoflabellina reticulata from the Rügen chalk , a key fossil for the Maastrichtian

This is of great importance for the petroleum industry. When drilling, the species can be used to identify whether climatic conditions were favorable for the formation of oil deposits in earlier times.

Foraminifera also play an important role in paleoclimatology as a proxy for reconstructing the climate of past geological ages. Foraminifera from limnic or marine sediment cores are used especially for the creation of the oxygen isotope levels , on the basis of which a distinction is made between warm and cold periods . Here, a is carried age dating based on the ratio of the isotopes 16 O and 18 O. Local the reduced ocean temperatures of Foraminifere act during the cold periods on the isotopic ratio of the calcareous shell, because this fractionated during installation of the calcium carbonate in its housing, the 16 O / 18 O -Ratio at lower temperatures towards the heavier isotope ( temperature effect ). An increased evaporation in the habitat of the foraminifera, but also an increased entry of isotopically lighter melt water lead to a shift in the 16 O / 18 O ratio in the water and thus in the housing ( salinity effect ).

Systematics

Adl et al. 2007 classified the foraminifera as one of the five taxa within the Rhizaria , of which they are by far the largest group. On the basis of family trees determined by molecular biology, the foraminifera represented the sister group of the genus Gromia and accordingly formed a common taxon with them. More recent molecular biological studies from 2012, according to Adl et al. however, that the genus Gromia is not a sister group. The closest relatives are probably the Acantharia and the Polycystinea .

The foraminifera comprise around 10,000 recent and 40,000 known fossil species in around 65 superfamilies and 300 families, around 150 of them recent.

The internal systematics of the group, however, is still largely unclear from a molecular genetic point of view. Above all, the fact that the DNA required for this can usually only be obtained in insufficient quantities, since most foraminifera cannot be cultivated in the laboratory and DNA is only available from extremely few species, makes extensive and representative studies difficult. Technical obstacles also make the creation of phylogenetic family trees difficult: so-called long branch attraction artifacts often lead to serious statistical errors in the context of the SSU rDNA, which is often used for investigations . Therefore, only the use of experimental marker genes ( actin , RNA polymerase II gene) was able to stabilize the initial results. It is clear from all investigations that the orders Allogromiida and Astrorhizida form a paraphyletic group together with some shell-less foraminifera, often listed as Athalamidae, and that the Miliolida emerged from them. The Globigerinida as well as the Buliminida are probably part of the Rotaliida.

All previous systematics are therefore still based on morphological features, also due to the large number of fossil species known exclusively through their housing. The current comprehensive system of foraminifera goes back to Alfred R. Loeblich and Helen Tappan and was introduced in 1992. It also served as the basis for the modified and supplemented systematics by Barun Sen Gupta from 2002, which is used here. The foraminifera are understood there as a class and subdivided into 16 orders († = extinct).

Barun Sen Gupta in front of the submarine " Alvin ", 2001

Subsequent molecular biological investigations indicate that the xenophyophores , which up to now were understood as a separate class of uncertain position , belong to the foraminifera and are closely related to the genus Rhizammina (Astrorhizida). Their exact position within the above system is not defined, however.

Research history

For a long time only the fossilized shells of the foraminifera were perceived by humans. Early authors did not recognize their origin as the housing of living things. Strabo interpreted the nummulites in the limestone of the pyramids of Giza as remains of the workers' excrement, and from the 16th to 18th centuries, as with all fossils, it was mostly assumed that they were simply stones.

Alcide d'Orbigny, first descriptor of the taxon "Foraminifera"

In 1700 Antoni van Leeuwenhoek documented the discovery of a foraminiferous shell “no bigger than a grain of sand” in the stomach of a shrimp . Regarded by him as a mollusc , it can be safely identified as a species of the genus Elphidium based on his drawing . Independently of this, Johann Jakob Scheuchzer said at the same time that "these stones are truly snails and not in the earth by I do not know what was formed before an archeum". This assignment to the molluscs was wrong, but at least the character of the foraminifera as a living being was now recognized. The pioneering work of Janus Plancus , who described some foraminifera from the beach of Rimini in 1739 , served Carl von Linné in 1758 as the basis for his placement of the species in the pearl boats ( Nautilus ).

As an independent systematic group, however, they only became manifest in 1826 with the first description of the foraminifera by Alcide d'Orbigny . If he originally saw them as the order of the cephalopods and thus remained within the traditional conception of the foraminifera as a group of molluscs, in 1839 he elevated them to a class of their own.

This was preceded by the first insights into the biology of the foraminifera, especially that of Félix Dujardin (1801–1860) on the structure of the actual "body". He called the contractile internal material, which spontaneously pushed through the pores of the calcareous shells in the form of pseudopodia , sarcode ; later this name was replaced by Hugo von Mohl (1805–1872) with the protoplasm that is still valid today . Félix Dujardin saw single-celled cells, rhizopods , as he called them, with shells ( Rhizopodes á coquilles ) in the foraminifera .

It was also D'Orbigny who began the paleontological research on the foraminifera, while at the same time mainly British researchers carried out the first ecological research. In the second half of the 19th century, the Challenger expedition , undertaken between 1873 and 1876, also proved extremely successful for foraminifera. Henry Bowman Brady's “Report on the Foraminifera dredged by HMS Challenger” , published in 1884, is considered a classic work on recent species to this day. At the same time, fundamental questions of cell structure (e.g. evidence of a cell nucleus by Hertwig and Schulze in 1877) and the life cycle (discovery of housing dimorphisms by Maximilian von Hantken in 1872, principles of propagation by Schaudinn and Lister 1894/95) could be clarified.

In the 20th century, the knowledge of the foraminifera was enriched mainly by three American researchers. Joseph Augustine Cushman laid the foundation of modern Foraminiferenforschung by next to the description of a huge number of new species and the Cushman Laboratory for Foraminiferal Research and the up to the present significant trade magazine "Contributions from the Cushman Laboratory for Foraminiferal Research" founded, today "Journal of Foraminiferal Research " . In the decade between 1931 and 1940, 3800 species were newly established, in 1935 around 360 papers on foraminifera appeared, and in 1936 twice as many. This knowledge explosion was due on the one hand to the increase in material due to sea expeditions, but on the other hand to the increased interest of the petroleum industry in foraminifera as reference fossils (indicators for the geological age of the earth's layer) in the stratigraphic analysis of oil wells.

In 1940 the first volume of the Catalog of Foraminifera by BF Ellis and AR Messina appeared, of which 94 volumes have appeared to date, listing almost every foraminifera ever described. The work, which is still being continued, is now available in digital form and contains almost 50,000 species.

After Cushman's death in 1949, the work of the couple Helen Tappan and Alfred R. Loeblich dominated the second half of the century. If Cushman was systematically attached to even older ideas, Loeblich and Tappan revised the systematics of the foraminifera fundamentally and published their results in two large monographic publications in 1964 and 1989, which are still relevant to the present day. Newer systematic approaches such as that of Valeria I. Mikhalevich are neither complete nor have they prevailed so far, nor have molecular biological studies (especially by Jan Pawlowski ).

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Footnotes directly after a statement cover the individual statement, footnotes behind a space before punctuation marks the entire preceding sentence. Footnotes after a space refer to the entire preceding text.

  1. ↑ Jan Pawlowski, Maria Holzmann, Cedric Berney, Jose Fahrni, Andrew J. Gooday, Tomas Cedhagen, Andrea Habura, Samuel S. Bowser: The evolution of early Foraminifera , In: Proceedings of the National Academy of Sciences of the USA, Vol. 100, pp. 11494-11498, 2003
  2. ↑ a b c d e Klaus Hausmann, Norbert Hülsmann, Renate Radek: Protistology , 3rd edition, 2003, ISBN 3-510-65208-8 , pp. 129-134
  3. ^ Rudolf Röttger, Gunnar Lehmann: Benthic foraminifera In: R. Röttger, R. Knight, W. Foissner (Eds.): A course in Protozoology , Protozoological Monographs Vol. 4, 2009, pp. 111–123, ISBN 3-8322 -7534-7
  4. ↑ a b c d Susan T. Goldstein: Foraminifera: A Biological Overview In: Barun K. Sen Gupta (Ed.): Modern Foraminifera . Springer Netherlands (Kluwer Academic), 2002, ISBN 978-1-4020-0598-5 , pp. 37-57 .
  5. ↑ Jacob, Wirth, Agbaje, Branson, Eggins: Systematics of modern Foraminifera In: 'Planktic foraminifera form their shells via metastable carbonate phases'. Nature Communications. doi: 10.1038 / s41467-017-00955-0
  6. ↑ a b c Barun K. Sen Gupta: Systematics of modern Foraminifera In: Barun K. Sen Gupta (Ed.): Modern Foraminifera . Springer Netherlands (Kluwer Academic), 2002, ISBN 978-1-4020-0598-5 , pp. 7-37 .
  7. ↑ a b Rudolf Röttger: Dictionary of Protozoology . In: Protozoological Monographs . tape 2 . Shaker, Aachen 2001, ISBN 3-8265-8599-2 , p. 83 .
  8. ^ Rudolf Röttger: Dictionary of Protozoology . In: Protozoological Monographs . tape 2 . Shaker, Aachen 2001, ISBN 3-8265-8599-2 , p. 182 .
  9. ↑ a b Klaus Nuglisch: Foraminiferen - marine Mikroorganismen , Wittenberg, 1985, “3. Cytoplasm and its structures ”, pp. 14–21
  10. ^ Rudolf Röttger: Dictionary of Protozoology . In: Protozoological Monographs . tape 2 . Shaker, Aachen 2001, ISBN 3-8265-8599-2 , p. 128 .
  11. ^ A b c John J. Lee, Jan Pawlowski, Jean-Pierre Debenay, John Whittaker, Fred Banner, Andrew J. Gooday, Ole Tendal, John Haynes, Walter W. Faber: Class Foraminifera In: John J. Lee, GF Leedale , P. Bradbury (Ed.): An Illustrated Guide to the Protozoa . tape 2 . Allen, Lawrence 2000, ISBN 1-891276-23-9 , pp. 877 .
  12. ↑ For the classification see z. E.g .: Rudolf Röttger, Robert Knight, Wilhelm Foissner (Eds.): A Course in Protozoology - Second revised edition In: Protozoological Monographs - Vol. 4, 2009
  13. ↑ Yuko Todo, Hiroshi Kitazato, Jun Hashimoto, Andrew J. Gooday: Simple Foraminifera Flourish at the Ocean's Deepest Point In: Science, 307: 5710, pp. 689, 2005
  14. ↑ a b c Klaus Nuglisch: Foraminiferen - marine Mikroorganismen , Wittenberg, 1985, “11.1 Benthosforaminiferen”, pp. 106–113
  15. ↑ a b Rudolf Röttger: Dictionary of Protozoology In: Protozoological Monographs, Vol. 2, 2001, pp. 96–98, ISBN 3-8265-8599-2
  16. ↑ Klaus Nuglisch: Foraminiferen - marine microorganisms , Wittenberg, 1985, “5. Symbionts ”, pp. 25-28
  17. ↑ a b c d Pamela Hallock: Symbiont-bearing Foraminifera In: Barun K. Sen Gupta (Ed.): Modern Foraminifera . Springer Netherlands (Kluwer Academic), 2002, ISBN 978-1-4020-0598-5 , pp. 123-139 .
  18. ↑ Pallavi Anand, Henry Elderfield , and Maureen H. Conte: Calibration of Mg / Ca thermometry in planktonic foraminifera from a sediment trap time seriens In: Paleoceanography, 18 (2), p. 1050
  19. ^ A b c Maria Holzmann, Andrea Habura, Hannah Giles, Samuel S. Bowser, Jan Pawlowski: Freshwater Foraminiferans Revealed by Analysis of Environmental DNA Samples In: Journal of Eukaryotic Microbiology, Vol. 50, No. 2, 2003, p. 135 -139
  20. ↑ Jan Pawlowski, Ignacio Bolivar, Jose F. Fahrni, Colomban De Vargas, Samuel S. Bowser: Molecular evidence that Reticulomyxa filosa is a freshwater naked foraminifer In: Journal of Eukaryotic Microbiology, 1999, Vol. 46, pp. 612-617
  21. ↑ Ralf Meisterfeld, Maria Holzmann, Jan Pawlowski: Morphological and Molecular Characterization of a New Terrestrial Allogromiid Species: Edaphoallogromia australica gen. Et spec. nov. (Foraminifera) from Northern Queensland (Australia) In: Protist, 152: 3, 2001, pp. 185-192
  22. ↑ Maria Holzmann, Jan Pawlowski: Freshwater Foraminiferans From Lake Geneva: Past And Present in: The Journal of Foraminiferal Research, 2002, Vol. 32, No. 4, pp. 344-350
  23. ↑ Klaus Nuglisch: Foraminiferen - marine microorganisms , Wittenberg, 1985, “1. Introduction ”, pp. 5–7
  24. ↑ a b c d e f g Klaus Nuglisch: Foraminiferen - marine microorganisms , Wittenberg, 1985, “2. History of Foraminifer Research ”, pp. 7-14
  25. ↑ Bernhard Ziegler: Introduction to Paleobiology Part 2 , Schweizerbart'sche Verlagsbuchhandlung Stuttgart, 1983, p. 25
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  27. ↑ James D. Wright: Global climate change in marine stable isotope records. In: JS Noller, JM Sowers, WR Lettis (eds.): Quaternary Geochronology: Methods and Applications , AGU Ref. Shelf, Vol. 4, pp. 427-433, doi: 10.1029 / RF004p0427 .
  28. ↑ Sina M. Adl, Brian S. Leander, Alastair GB Simpson, John M. Archibald, et al .: Diversity, Nomenclature and Taxonomy of Protists (=  Systematic Biology . Volume 56 , no. 4 ). Oxford Journals, 2007, pp. 685 , doi : 10.1080 / 10635150701494127 ( online ).
  29. ↑ a b Sina M. Adl, Alastair GB Simpson, Christopher E. Lane, Julius Lukeš, David Bass, Samuel S. Bowser, Matthew W. Brown, Fabien Burki, Micah Dunthorn, Vladimir Hampl, Aaron Heiss, Mona Hoppenrath, Enrique Lara , Line le Gall, Denis H. Lynn, Hilary McManus, Edward AD Mitchell, Sharon E. Mozley-Stanridge, Laura W. Parfrey, Jan Pawlowski, Sonja Rueckert, Lora Shadwick, Conrad L. Schoch, Alexey Smirnov, A. and Frederick W. Spiegel: The Revised Classification of Eukaryotes (=  The Journal of Eukaryotic Microbiology . Volume 59 , no. 5 ). International Society of Protistologists, 2012, p. 429-514 , doi : 10.1111 / j.1550-7408.2012.00644.x .
  30. ↑ Samuel S. Bowser, Andrea Habura, Jan Pawlowski: Molecular evolution of Foraminifera In: Laura Katz Olson, Laura A. Katz, Debashish Bhattacharya: Genomics and Evolution of Microbial Eukaryotes , 2006, pp. 78–94, ISBN 0-19- 856974-2
  31. ↑ a b David Longet, Jan Pawlowski: Higher-level phylogeny of Foraminifera inferred from the RNA polymerase II (RPB1) gene In: European Journal of Protistology, 43 (2007), pp. 171-177
  32. ↑ Jerome Flakowski, Ignacio Bolivar, Jose Fahrni, Jan Pawlowski: Actin Phylogeny Of Foraminifera In: Journal of Foraminiferal Research, 2005, Volume 35, pp. 93-102
  33. ↑ Sina M. Adl, Alastair GB Simpson, Mark A. Farmer, Robert A. Andersen, O. Roger Anderson, John A. Barta, Samual S. Bowser, Guy Brugerolle, Robert A. Fensome, Suzanne Fredericq, Timothy Y. James , Sergei Karpov, Paul Kugrens, John Krug, Christopher E. Lane, Louise A. Lewis, Jean Lodge, Denis H. Lynn, David G. Mann, Richard M. McCourt, Leonel Mendoza, Øjvind Moestrup, Sharon E. Mozley-Standridge , Thomas A. Nerad, Carol A. Shearer, Alexey V. Smirnov, Frederick W. Spiegel, Max FJR Taylor: The New Higher Level Classification of Eukaryotes with Emphasis on the Taxonomy of Protists (=  The Journal of Eukaryotic Microbiology . Volume 52 , no. 5 ). International Society of Protistologists, 2005, p. 418 , doi : 10.1111 / j.1550-7408.2005.00053.x .
  34. ↑ Jan Pawlowski, Maria Holzmann, Jose Fahrni, Susan L. Richardson: Small Subunit Ribosomal DNA Suggests that the Xenophyophorean Syringammina corbicula is a Foraminiferan In: Journal of Eukaryotic Microbiology, 50: 6, 2003, pp. 483-487
  35. ↑ Barun K. Sen Gupta: Introduction to modern Foraminifera In: Barun K. Sen Gupta (Ed.): Modern Foraminifera . Springer Netherlands (Kluwer Academic), 2002, ISBN 978-1-4020-0598-5 , pp. 3-6 .
  36. ↑ Entry in DEBIS, online
  37. ↑ Valeria I. Mikhalevich: About the heterogeneous composition of the former group Textulariina (Foraminifera) - German translation of the text part and the literature references by: Valeria I. Mikhalevich: On the heterogeneity of the former Textulariina (Foraminifera) In: Proc. 6th intern. Workshop agglutinated foraminifera. , Grzybowski Foundation Spec. Publ., 2004, Vol. 8., pp. 317-349, PDF Online

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This article was added to the list of excellent articles on September 22, 2009 in this version .