The Crystallography and Possible Origin of Barium Sulphate in Deep Sea Rhizopod Protists (Xenophyophorea)

Hopwood, Jeremy D.; Mann, Stephen; Gooday, Andrew J.

doi:10.1017/s002531540003856x

Cited by 33 publications

(21 citation statements)

References 37 publications

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“…7B) that occupies <5 per cent by volume of the test (Levin and Gooday 1992). It contains crystals of barium sulphate (BaSO 4 ), 2–5 μm in size, the origin and function of which remains obscure (see Gooday and Nott 1982; Hopwood et al . 1997).…”

Section: The Xenophyophoresmentioning

confidence: 99%

Testing the protozoan hypothesis for Ediacaran fossils: a developmental analysis ofPalaeopascichnus

Antcliffe¹,

Gooday²,

Brasier³

2011

Palaeontology

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The hypothesis that the Ediacara biota were giant protozoans is tested by considering the external morphology, internal organization, suggested fossil representatives and molecular phylogeny of the xenophyophores. From this analysis, we find no case to support a direct relationship. Rather, the xenophyophores are here regarded as a group of recently evolved Foraminifera and are hence unlikely to have a record from the Ediacaran Period. Further from the growth dynamics of Foraminifera, they are also unlikely to be related to the Palaeopascichnus organism. We also find significant distinctions in the growth dynamics of Palaeopascichnus and organisms usually referred to the Ediacara biota, such as Charnia and Dickinsonia. Developmental analysis of the Palaeopascichnus -central to the xenophyophore hypothesis -reveals unusual, protozoan features, including evidence for chaotic repair structures, for mergence of coeval forms, as well as complex bifurcations. These observations suggest that Palaeopascichnus is a body fossil of an unidentified protozoan but is unrepresentative of Ediacaran body construction, in general.Key words: Palaeopascichnus, Ediacara biota, Protozoa, xenophyophores, development, evolution.The fossil record contains a great conundrum; the modern animal phyla appear already distinguished as fossils within the Cambrian System (Brasier 1979). This system lies immediately above the recently named Ediacaran System (Knoll et al. 2004). From the time of Darwin to the discovery of the global Ediacara biota (Gürich 1933; Sprigg 1947; Ford 1958), the ancestry of animals has remained one of the most exciting mysteries in science. Indeed, Darwin (1859) stated that one of the greatest flaws in his hypothesis was the lack of demonstrable ancestry to the recognized phyla that appear distinct at the base of the known fossil record (then 'Silurian', now the base of the Cambrian). After the great antiquity of the Ediacara biota had been realized (Ford 1958), then the Ediacara biota was interpreted as primitive metazoans (Glaessner 1966(Glaessner , 1984 Glaessner and Daily 1959; Glaessner and Wade 1966; Wade 1972; Jenkins 1984 Jenkins , 1985 Jenkins , 1992 Jenkins , 1995 Jenkins and Gehling 1978; McMenamin 1986 McMenamin , 1998 Bengtson 2003), thereby providing putative solutions to the long posed problem regarding animal ancestry.This view of Ediacaran palaeobiology was refocused by Seilacher , 1985, 1989, 1992 also Buss and Seilacher 1994), who questioned the evidence for continuity between the Ediacara biota and succeeding Cambrian metazoans. Seilacher (1989) also challenged the taxonomy by stating that many Ediacaran organisms share a common construction. This was taken to imply that they are, for the most part, a single clade unrelated to modern groups. A profusion of taxonomic affinities has followed (e.g. Dzik 2003; Gehling 1991; Jenkins 1992; Valentine 1992; Seilacher 2003; Seilacher et al. 2003; Peterson et al. 2003; Narbonne 2005). These taxonomies were based upon simple morphologic...

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Section: The Xenophyophoresmentioning

confidence: 99%

Testing the protozoan hypothesis for Ediacaran fossils: a developmental analysis ofPalaeopascichnus

Antcliffe¹,

Gooday²,

Brasier³

2011

Palaeontology

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“…In contrast, the knowledge of trace metal accumulation patterns in abyssal epi-and endobenthic species, among which the deposit feeder type predominates, is very poor. The in the abyssal basins widely distributed Xenophyophoria, rhizopod protists which can reach enormous body sizes of >10 cm in diameter, accumulate BaSO 4 crystals (termed "granellae") in their protoplasm (HOPWOOD et al, 1997). These, together with other structures, characterise this animal class and serve to distinguish the Xenophyophoria from the closely related Foraminifera.…”

Section: Trace Metals In Deep-sea Organismsmentioning

confidence: 99%

Reactions of the Heavy Metal Cycle to Industrial Activities in the Deep Sea: An Ecological Assessment

Koschinsky

Borowski

Halbach

2003

International Review of Hydrobiology

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This article focuses on possible geochemical consequences of potential industrial activities in the deep sea, such as manganese nodule mining, for the heavy metal cycle of the deep sea and possible reactions of the benthic ecosystem. The metal fluxes induced by sediment resuspension are compared with fluvial, atmospheric, and hydrothermal metal fluxes into the ocean. The results of geochemical laboratory experiments and analyses of deep-sea benthic organisms are discussed with respect to their ecological importance in case of a seabed disturbance.A limited short-term increase of heavy metal concentrations in the benthic layer will probably cause only negligible harmful effects on the biota. An essential precondition is that the geochemical milieu remains largely unchanged; especially variations of the redox conditions would result in changes in metal speciation, bioavailability, and toxicity.1. Introduction Ferromanganese Nodules as Potential Sources for Heavy Metal Contamination in Deep-Sea EnvironmentsThe deep-sea basins, e.g., the Peru Basin in the southern Central Pacific and the ClarionClipperton-Fracture Zone in the northern Central Pacific, contain metal-rich manganese nodules of potential economic interest (HALBACH et al., 1988). Intense scientific work was carried out in the seventies and eighties to investigate the geochemistry and metal potential of these deposits (e.g., CRONAN, 1977;CALVERT, 1978;PIPER and WILLIAMSON, 1977;EXON, 1983;DYMOND et al., 1984;GLASBY et al., 1986). However, it was soon recognized that mining of these resources would cause a number of rapid changes of the environmental conditions in large deep-sea areas which naturally can happen only in geological time scales (AMOS, 1977;PADAN, 1990;THIEL et al., 1993). Consequently, the potential effects of deepsea mining became subject of scientific activities which lead, e.g., to the publication of a special issue of Marine Mining (Vol. 3, nos. 1/2, 1981) and to the organization of a Dahlem Workshop (1991) that was dedicated to various aspects of the use and misuse of the seafloor (HSÜ and THIEDE, 1992). Some recent articles give overviews on environmental impact investigations during the past 25 years, such as the American DOMES (Deep-Ocean Mining Environmental Studies) and BIE (Benthic Impact Experiment) studies and the Ger-

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“…The first is Heron-Allen (1915) who speculated that the concentration of heavy minerals as a result of rapid settlement following wave/current agitation could increase the chances of foraminifera agglutinating these denser particles. Also, a group of large agglutinated foraminifera, namely Xenophyophores, show a similar ballasting behavior when ingesting barite crystals (Gooday & Nott, 1982;Hopwood et al, 1997), or other minerals, tentatively identified as ilmenite, rutile, and anatase (Rothe et al, 2011). In contrast, the ingestion of heavy minerals by softwalled, single-chambered taxa such as Psammophaga has rarely been discussed; Nyholm (1957) and Dahlgren (1962) proposed that the presence of mineral grains inside their cells helps light, soft-walled foraminifera to anchor themselves in very soft mud.…”

Section: Advantage Of Selective Mineral Inclusionsmentioning

confidence: 94%

“…Therefore the ingestion of heavy minerals by Psammophaga may be related to problems with buoyancy. Also, a group of large agglutinated foraminifera, namely Xenophyophores, show a similar ballasting behavior when ingesting barite crystals (Gooday & Nott, 1982;Hopwood et al, 1997), or other minerals, tentatively identified as ilmenite, rutile, and anatase (Rothe et al, 2011). It is possible that, in addition to the ballasting effect, the foraminifera ingest zircon instead of dark minerals of similar specific density for camouflage in the silicate-dominated sediment, allowing them to escape predators.…”

Section: Advantage Of Selective Mineral Inclusionsmentioning

confidence: 99%

Selective zircon accumulation in a new benthic foraminifer, Psammophaga zirconia, sp. nov.

et al. 2016

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Benthic foraminifera are single-celled eukaryotes that make a protective organic, agglutinated or calcareous test. Some agglutinated, single-chambered taxa, including Psammophaga Arnold, 1982, retain mineral particles in their cytoplasm, but the selective mechanism of accumulation is not clear. Here, we report the ability of a foraminiferal species to select and accumulate zircons and other heavy minerals in their cytoplasm. In particular, the use of Scanning Electron Microscope coupled with an Energy Dispersive X-ray microanalysis system (SEM-EDS) enabled a representative overview of the mineral diversity and showed that the analysed Psammophaga zirconia sp. nov. individuals contained dominantly crystals of zircon (51%), titanium oxides (27%), and ilmenite (11%) along with minor magnetite and other minerals. The studied specimens occur in the shallow central Adriatic Sea where the sediment has a content of zircon below 1% and of other heavy minerals below 4%. For that reason we hypothesize that: (i) P. zirconia may be able to chemically select minerals, specifically zircon and rutile; (ii) the chemical mechanism allowing the selection is based on electrostatic interaction, and it could work also for agglutinated foraminifera (whether for ingestion, like Xenophyophores, or incorporation in the test as in many other described taxa). In particular, this aptitude for high preferential uptake and differential ingestion or retention of zircon is reported here for the first time, together with the selection of other heavy minerals already described in members of the genus Psammophaga. They are generally counted among early foraminifera, constructing a morphologically simple test with a single chamber. Our molecular phylogenetic study confirms that P. zirconia is a new species, genetically distinctive from other Psammophaga, and occurs in the Adriatic as well as in the Black Sea.

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The Crystallography and Possible Origin of Barium Sulphate in Deep Sea Rhizopod Protists (Xenophyophorea)

Cited by 33 publications

References 37 publications

Testing the protozoan hypothesis for Ediacaran fossils: a developmental analysis ofPalaeopascichnus

Testing the protozoan hypothesis for Ediacaran fossils: a developmental analysis ofPalaeopascichnus

Reactions of the Heavy Metal Cycle to Industrial Activities in the Deep Sea: An Ecological Assessment

Selective zircon accumulation in a new benthic foraminifer, Psammophaga zirconia, sp. nov.

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