How is energy generated by foraminifera

Foraminifera

Foraminifera

Ammonia tepida

Systematics
Scientific name
Foraminifera
d'Orbigny, 1828

The unicellular onesForaminifera (Foraminifera), rarely too Chamberlains called, are a taxon of 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, live planktonically. The majority of all foraminifera are characterized by an enclosure.

The extraordinarily diverse group has been fossilized since the Cambrian (around 560 million years ago), but studies of the molecular clock point to a significantly older age of 690 to 1150 million years [1]. Foraminifera are used in paleontology as reference fossils of the Cretaceous, Palaeogene 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 up to several months or even a few years [2]. The majority of living species are between 200 and 500 micrometers in size, the smallest representatives only measure up to 40 micrometers (Rotaliella roscoffensis) and the largest up to 12 (Cycloclypeus carpenteri) or even 20 centimeters (Acervulina) [3]. Almost all types usually have a multi-chambered housing. Through its usually fine perforation, thread-like, thin, interlinked pseudopods emerge. [4]

casing

The housings 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 large foraminifera, off Japan

Building material

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

By far the largest group, secretory lime is used as a building material, almost always in the form of calcite, very rarely also as aragonite. For a more precise systematic breakdown, the building material can be further differentiated, especially on the basis of its magnesium content (high / low). In contrast, in agglutinating foraminifera, grains of sand or other foreign bodies that have been taken up from the sediment are glued together on a mineral or proteinaceous basis. They thus 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. [5]

A special case, however, is that only from the genus Miliammellus existing order Silicoloculinida, in which opal casings are found (SiO2 x n H2O). [5]

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) [2]. The dividing walls of the chambers ("septae") are each 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. [6]

Multi-chamber housings can be arranged in different ways. 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, i.e. made up of three staggered rows, are also called trochospiral and form a contrast to plane-spiral housings. With the latter, every revolution of the spiral takes place on the same plane as the previous one, so the housing remains flat in the side view. Trochospiral housings, on the other hand, are made of helical spirals that widen with each revolution, they have a bulging spiral side and a flattened underside. 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 so-called umbilicus, the navel. [6]

The shells of the sand-shelled Textulariida as well as 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. [7]

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. [8]

There is no clear differentiation between endoplasm and ectoplasm, but the housing is covered by a thin layer of cytoplasm, which also forms the reticulopodia. [8]

Reticulopodia

Like all root pods, the foraminifera also have 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 to a diameter of less than a micrometer at their respective ends[2]. [4]

In contrast to other pseudopods, the pseudopods of the foraminifera have the ability to anastomose, so they can branch out and merge with other pseudopods. In this way, foraminifera can form a complex network outside their body that can spread over an area of ​​several hundred square centimeters. In this case, one speaks of reticulopodia. [2]

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 [2]. The guiding structure for the so-called “granule flow” is represented by bundles of microtubules through which mitochondria, dense bodies, enveloped and elliptical vesicles within the reticulopodia are transported in two directions at the same time (bidirectional). The phagosomes or defecation vacuoles, which also appear as granules, are, however, only transported unidirectionally. [9]

Life cycle

The life cycles of foraminifera species have only been sparsely researched up to the present; for less than 30 of the approximately 10,000 species they are fully known. 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 is, however, extraordinarily high; almost every characteristic of the typical life cycle has a different form. [4]

In addition to sexual reproduction, single-chambered foraminifera species in particular can also reproduce asexually, pathways are budding, cell division and cytotomy[10].

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 living on the sea floor, is classic. A special group of benthic foraminifera are the around 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, but no information can yet be given about the final size of this group. [11]

Shells of benthic foraminifera from North America, (starting clockwise at the top left: Ammonia beccarii, Elphidium excavatum clavatum, Buccella frigida, Eggerella advena, SEM image, various 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 [12]. On the ground, they can be firmly attached to the substrate or roam freely, but the transitions are fluid and the states are often temporary. [13]

To attach, benthic species require solid subsoil, on which they can usually be found by means of their pseudopodia (e.g. for Astrorhiza limicola, Elphidium crispum, Bathysiphon spp.), but also with organic membranes (Patellina corrugata), Adhesive disks (Halyphysema) or sulfuric acid 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, hydrozoans or brachiopods, where they act as commensals in the food stream. They are found epiphytically in algae or seagrass vegetation, where accumulating detritus forms their nutritional basis. On less firm 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.[13]

Species living without light often function as decomposers of detritus, especially those of phytoplanktic origin, while deep-sea species live on material that is already more strongly decomposed. In addition, there are carnivorous, herbivorous or omnivorous species that feed on pastures, destructors, filter feeders or parasites, but many species specialize in their diet on individual prey groups. Some of these species also have a planktonic way of life at times [13]. [4]

Large foraminifera

"Star Sand", Okinawa

The special group of large foraminifera, which comprises around fifty species, is usually separated from the benthic foraminifera [14]. 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, their number is estimated to be over 100,000 Peneroplis pertusus or around 150,000 Heterostegina depressa[15]. [16]

Fusulunide large foraminifera

Large foraminifera are purely tropical or subtropical; they reach their highest biodiversity in the Indo-Pacific region, but are also 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 most well-known representatives are the species of the genus Baculogypsinawhose characteristically shaped housings form the so-called “star sand” on the beaches of the Ryukyu Islands. The most common type, however, is Heterostegina depressa. [16]

The existing populations of large foraminifera are considered relics of much more diverse groups. B. in the Carboniferous and Permian (Fusulinida) or in the Tertiary sediment-forming distribution possessed. They mostly live in large groups and are so-called K-strategists who use limited resources and whose adequate use only grows slowly and have constant population sizes. Their lifespan is remarkable, which can be up to several years and cannot be reached by any other single-cell organisms. [14]

Planktic foraminifera

With fewer than fifty known species, all of which belong to the order Globigerinida, the proportion of foraminifera living in plankton is small in terms of the number of species large biomass. They are widespread in polar to tropical seas, and a particularly large number of species are 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 [17]. Many species, like the large foraminifera, harbor photosynthetic symbionts in the form of the specialized dinoflagellates Gymnodinium beii or golden brown algae. [16]

Freshwater foraminifera

The classic idea of ​​foraminifera as exclusively marine organisms with shells has been called into question by research results since the turn of the millennium. Several freshwater species from Lake Geneva were first described as early as the second half of the 19th century, as was the case with the one known since 1949 Reticulomyxa filosa but if their systematic position was unclear, they were usually placed in groups other than the foraminifera. The size of the group, its distribution and way of life was almost unexplored. In 2003 Maria Holzmann wrote: “Freshwater foraminifera are one of the most puzzling groups of protists [18]". Molecular biological investigations have proven that some of them are foraminifera[19], [20], but by sequencing environmental samples from different origins, it was also possible to establish that there are numerous still unknown species. As a summary of these samples, contrary to previous assumptions, it could be determined that “Foraminifera are widespread in freshwater environments [18]“, The first description of an even terrestrial species like Edaphoallogromia australica shows that foraminifera also spread outside of water bodies. [21],[18]

paleontology

Petrified large foraminifera

Decay-resistant housings can fossilize after the cell dies and thus be preserved. On the basis of fossil foraminifera associations, one can reconstruct the environmental conditions of bygone 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) [22]. Famous such rocks are the chalk cliffs of Dover and the rocks used in the construction of the Egyptian pyramids [10]. [23]

This is of great importance for the petroleum industry. When drilling, one can see from the species whether climatic conditions prevailed here in earlier times that were also necessary for the formation of oil deposits. [23]

Systematics

Adl et al. classify 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 represent the sister group of the genus Gromia and probably form a common taxon with them. [24] They include around 10,000 recent and 40,000 known fossil species[25] in around 65 superfamilies and 300 families, around 150[16] of which recently.

The internal systematics of the group, on the other hand, 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. [26] Technical obstacles also make the creation of phylogenetic 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, so only the use of experimental marker genes (actin-[27], RNA polymerase II gene [26]) stabilize the initial results. It is clear from all investigations that the orders Allogromiida and Astrorhizida together with some shell-less foraminifera, often listed as Athalamidae, form a paraphyletic group 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 [28]. 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). [5]

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) are. However, their exact position within the above system is not defined. [29]

Research history

Foraminifera were only perceived by humans through their fossilized shells. Early authors did not even understand their origin as the housing of a living being, so Strabo interpreted the nummulites in the limestone of the pyramids of Giza as the remains of the worker's feces, and in the 16th to 18th centuries, like all fossils, it was mostly assumed that they were acting are simply stones. [23]

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. Based on his drawing, it can be safely identified as a species of the genus Elphidium that Leeuwenhoek regarded as a mollusc [30]. Independently of this, Johann Jakob Scheuchzer stated at the same time that "these stones are truly snails and not in the earth by I do not know what was formed in front of an archeum" [23]. 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). [23]

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 regarded them as the order of the cephalopods and thus stayed 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 findings on the biology of the foraminifera, in particular on the structure of the actual "body" by Félix Dujardin (1801-1860). He named the contractile internal substance that spontaneously pushed through the pores of the calcareous shells in the form of pseudopodia Sarcode; later this designation was transferred by Hugo von Mohl (1805-1872) to the term protoplasm, which is still valid today. Félix Dujardin saw single-celled rhizopods in the foraminifera, as he called them, with shells (Rhizopodes á coquilles).

It was also D’Orbigny who began 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, which took place between 1873 and 1876, also proved to be extremely successful for foraminifera. Henry Bowman Brady's 1884 published "Report on the Foraminifera dredged by H.M.S. Challenger“Is considered a classic work on recent species to the present 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. [23]

In the 20th century, it was primarily three US researchers who enriched our knowledge of the foraminifera. Joseph Augustine Cushman laid the foundation for modern foraminifera research by describing a vast number of new species as well as the Cushman Laboratory for Foraminiferal Research as well as the specialist magazine, which is important to the present day "Contributions from the Cushman Laboratory for Foraminiferal Research" founded, today "Journal of Foraminiferal Research". In the decade between 1931 and 1940, 3800 species were reorganized, in 1935 around 360 papers on foraminifera appeared, and in 1936 it was twice as much. 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 oil industry in foraminifera as indicators in the stratigraphic analysis of oil wells. [23]

In 1940 the first volume of the Catalog of Foraminifera by B. F. Ellis and A. R. Messina, 94 volumes of which have appeared to date, listing almost every foraminifera ever described [10]. The work, which is still being continued, is now available in digital form and contains almost 50,000 species [31].

After Cushman's death in 1949, it was the couple Helen Tappan and Alfred R. Loeblich whose work dominated the second half of the century. If Cushman was systematically attached to even older ideas, Loeblich and Tappan fundamentally revised the systematics of the foraminifera in two large monographic works in 1964 and 1989; their work is still relevant to the present day. More recent systematic approaches such as that of Valeria I. Mikhalevich[32] are neither complete nor have they prevailed, nor have molecular biological studies (especially by Jan Pawlowski).

See also

proof

  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. abcde 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. abcd 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. abc 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.
  6. abRudolf Röttger: Dictionary of Protozoology. In: Protozoological Monographs. Vol. 2, Shaker, Aachen 2001, ISBN 3-8265-8599-2, p. 83.
  7. ^ Rudolf Röttger: Dictionary of Protozoology. In: Protozoological Monographs. Vol. 2, Shaker, Aachen 2001, ISBN 3-8265-8599-2, p. 182.
  8. ab Klaus Nuglisch: Foraminifera - marine microorganisms, Wittenberg, 1985, “3. Cytoplasm and its structures ”, pp. 14-21
  9. ^ Rudolf Röttger: Dictionary of Protozoology. In: Protozoological Monographs. Vol. 2, Shaker, Aachen 2001, ISBN 3-8265-8599-2, p. 128.
  10. abc 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, Gordon F. Leedale, Phyllis Bradbury (Eds.): Illustrated Guide to the Protozoa, 2nd Edition. Vol. 2, Society of Protozoologists, Lawrence, Kansas 2000, ISBN 1-891276-23-9, pp. 877.
  11. ↑ For the classification see e.g .: Rudolf Röttger, Robert Knight, Wilhelm Foissner (Eds.): A Course in Protozoology - Second revised edition In: Protozoological Monographs - Vol. 4, 2009
  12. ↑ 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
  13. abc Klaus Nuglisch: Foraminifera - marine microorganisms, Wittenberg, 1985, “11.1 Benthosforaminiferen”, pp. 106-113
  14. ab Rudolf Röttger: Dictionary of Protozoology In: Protozoological Monographs, Vol. 2, 2001, pp. 96-98, ISBN 3826585992
  15. ↑ Klaus Nuglisch: Foraminifera - marine microorganisms, Wittenberg, 1985, “5. Symbiotees ”, pp. 25-28
  16. abcd Pamela Hallock: Symbiote-bearing Foraminifera In: Barun K. Sen Gupta (Ed.): Modern foraminifera. Springer Netherlands (Kluwer Academic), 2002, ISBN 978-1-4020-0598-5, pp. 123-139.
  17. ↑ 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
  18. abc 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, pp. 135-139
  19. ↑ 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
  20. ^ 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
  21. ^ 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
  22. ↑ Klaus Nuglisch: Foraminifera - marine microorganisms, Wittenberg, 1985, “1. Introduction ”, pp. 5-7
  23. abcdefG Klaus Nuglisch: Foraminifera - marine microorganisms, Wittenberg, 1985, “2. History of Foraminifer Research ”, pp. 7-14
  24. ↑ Adl, Sina M., Leander, Brian S., Simpson, Alastair GB, Archibald, John M., Anderson, O. Roger., Bass, David, Bowser, Samuel S., Brugerolle, Guy, Farmer, Mark A. , Karpov, Sergey, Kolisko, Martin, Lane, Christopher E., Lodge, Deborah J., Mann, David G., Meisterfeld, Ralf, Mendoza, Leonel, Moestrup, Øjvind, Mozley-Standridge, Sharon E., Smirnov, Alexey V. and Spiegel, Frederick (2007) Diversity, Nomenclature and Taxonomy of Protists, In: Systematic Biology, 56: 4, 685
  25. ↑ 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
  26. ab 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
  27. ↑ Jerome Flakowski, Ignacio Bolivar, Jose Fahrni, Jan Pawlowski: Actin Phylogeny Of Foraminifera In: Journal of Foraminiferal Research, 2005, Volume 35, pp. 93-102
  28. ↑ 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 52 (5), 2005; Page 418
  29. ↑ 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
  30. ↑ 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.
  31. ↑ Entry in DEBIS, online
  32. ↑ Valeria I. Mikhalevich: About the heterogeneous composition of the former group Textulariina (Foraminifera) - German translation of the text and the 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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