Occultammina

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Occultammina
Occultammina sp.png
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Phylum: Retaria
Subphylum: Foraminifera
Class: Monothalamea
Clade: Xenophyophorea
Order: Psamminida
Family: Syringamminidae
Genus: Occultammina
Tendal et al., 1982
Type species
Occultammina profunda
Tendal et al., 1982

Occultammina is a genus of xenophyophorean foraminifera known from the Atlantic and Pacific oceans. It is notable for being the first known infaunal xenophyophore as well as for being a possible identity for the enigmatic trace fossil Paleodictyon .

Contents

Distribution and habitat

Like all other known xenophyophores, Occultammina is found in the deep ocean; the first known specimen was first discovered in 1980 at a depth of 8,260 m (27,100 ft) in the Ogasawara Trench, off the coast of Japan and described in 1982 by a joint research team from the University of Copenhagen and the University of Tokyo. [1] Further specimens referred to Occultammina sp. have been found at a depth of 4,844 m (15,892 ft) in the Porcupine Abyssal Plain, in the North Atlantic. [2] Further studies have expanded its geographical and bathymetric range from 3,000 and 8,260 metres (9,840 and 27,100 ft) in the Ogasawara Trench and from 4,500 to 4,800 metres (14,800 to 15,700 ft) in the North Atlantic, and also recorded its presence at 6,440 m (21,130 ft) in the Japan trench. [2] Occultammina sp. has also been recovered at a depth of about 4,050 metres (13,290 ft) near the Clipperton fracture zone, off the coast of western Mexico. [3]

Occultammina is infaunal; it typically is found at a depth of 6 cm (2.4 in) or less below the sediment's surface. [2] It was the first known infaunal xenophyophore. [4]

Occultammina is found at turbidite facies in today's oceans. [1]

Description

Occultammina is an exceptionally large single-celled organism; like other xenophyophores it constructs a complex, single-chambered shell or "test" from sediment particles. It grows in a net-like shape, the test consisting of hollow tubes that branch or form loose polygons. It is typically flattened compared to other xenophyophores. [1] It also has vertically ascending tubular outlets. [2] Occultammina tubes are similar to those of Tendalia in general shape, though the test structure differs. [5]

The test wall typically ranges from 70 to 120 μm in thickness; it is poorly cemented and consists of two layers. The outermost is 15-30 μm in thickness and composed primarily from clay; the inner layer is 50-90 μm thick and composed of silt and radiolarian tests. The interior of the test lining has between one and four ridges separating the stercomares, or waste masses.

Individual Occultammina tubes are between 0.38 and 1 cm (0.15 and 0.39 in) in diameter. [1] [4] Networks of Occultammina sized 5–10 cm (2.0–3.9 in) across have been found at the Ogasawara trench. [2]

A specimen of Occultammina profunda was found to have unusually high levels of the radioactive isotopes lead-210 (half-life 22.3 years), polonium-210 (half-life 138.376 days) and radium-226 (half-life 1600 years), specifically in the grannelare and stercomare, among the highest levels of lead-210 recorded in any living organism. The authors suggest that the relative distribution of radionuclides in the organism's body parts implies that it grows and excretes comparatively rapidly. [6]

Unfortunately no DNA samples have been collected from Occultammina, preventing further examination of its evolutionary relationships. [5]

Relation to Paleodictyon

The enigmatic fossil Paleodictyon has been likened to Occultammina Paleodictyon P.San Garcia Algeciras S03.JPG
The enigmatic fossil Paleodictyon has been likened to Occultammina

The enigmatic "graphoglyptid" fossil Paleodictyon bears a passing resemblance to Occultammina, and this has led to suggestions of relationship between the two. Paleodictyon fossils are known from sediments interpreted as representing abyssal paleoenvironments associated with turbidite deposits, potentially lending credence to the hypothesis. Paleodictyon also preserves vertically ascending tubules that have been likened to those of Occultammina.

However, this relationship has been contested. The large size (up to 0.5 m (1 ft 8 in)) of some Paleodictyon is unknown in modern Occultammina; the regular hexagonal pattern of Paleodictyon is similarly not represented in Occultammina. The apparent absence of collected sediment particles (known as xenophyae) in graphoglyptid fossils further casts doubt on the possibility. [2]

Modern examples of Paleodictyon have been discovered; however, they have not been able to clear up the issue. These specimens come from near the mid-Atlantic Ridge at a depth of 3,415–3,585 meters (11,204–11,762 ft). The specimens ranged from 2.4 to 7.5 cm (0.94 to 2.95 in) in diameter. Dissection of one specimen did not reveal tubes, mucus, protoplasm, or evidence of a test. Staining of a second specimen did not reveal soft-bodied evidence for xenophyophores such as stercomares or granellae; some small agglutinated fragments were found that could have been from a psamminid, but this is not unexpected in deep-sea sediments. DNA analysis also did not reveal evidence of xenophyophores in the sample. The modern samples also lacked the barium concentration caused by the barite crystals in xenophyophore tests. This study suggested that Paleodictyon could represent a burrow system or a glass sponge. [7]

Related Research Articles

<span class="mw-page-title-main">Xenophyophorea</span> Clade of single-celled organisms

Xenophyophorea is a clade of foraminiferans. Xenophyophores are multinucleate unicellular organisms found on the ocean floor throughout the world's oceans, at depths of 500 to 10,600 metres. They are a kind of foraminiferan that extract minerals from their surroundings and use them to form an exoskeleton known as a test.

<span class="mw-page-title-main">Foraminifera</span> Phylum of amoeboid protists

Foraminifera are single-celled organisms, members of a phylum or class of Rhizarian protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly an external shell of diverse forms and materials. Tests of chitin are believed to be the most primitive type. Most foraminifera are marine, the majority of which live on or within the seafloor sediment, while a smaller number float in the water column at various depths, which belong to the suborder Globigerinina. Fewer are known from freshwater or brackish conditions, and some very few (nonaquatic) soil species have been identified through molecular analysis of small subunit ribosomal DNA.

<span class="mw-page-title-main">Abyssal plain</span> Flat area on the deep ocean floor

An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3,000 and 6,000 metres. Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth's surface. They are among the flattest, smoothest, and least explored regions on Earth. Abyssal plains are key geologic elements of oceanic basins.

<span class="mw-page-title-main">Seabed</span> The bottom of an ocean

The seabed is the bottom of the ocean. All floors of the ocean are known as 'seabeds'.

<i>Gromia</i> Genus of protists

Gromia is a genus of protists, closely related to foraminifera, which inhabit marine and freshwater environments. It is the only genus of the family Gromiidae. Gromia are ameboid, producing filose pseudopodia that extend out from the cell's proteinaceous test through a gap enclosed by the cell's oral capsule. The test, a shell made up of protein that encloses the cytoplasm, is made up of several layers of membrane, which resemble honeycombs in shape – a defining character of this genus.

The Komokiacea are a small group of amoeboid protozoa, considered to be foraminifera, though there have been suggestions that they are a separate group, closely related to foraminifera. Komokiacea are rather large organisms, often exceeding 300 micrometers in maximum dimensions. Along with Xenophyophores they dominate the macro- and megabenthic fauna in the deep sea and are commonly referred to as "giants protists".

<span class="mw-page-title-main">Deep-sea exploration</span> Investigation of ocean conditions beyond the continental shelf

Deep-sea exploration is the investigation of physical, chemical, and biological conditions on the ocean waters and sea bed beyond the continental shelf, for scientific or commercial purposes. Deep-sea exploration is an aspect of underwater exploration and is considered a relatively recent human activity compared to the other areas of geophysical research, as the deeper depths of the sea have been investigated only during comparatively recent years. The ocean depths still remain a largely unexplored part of the Earth, and form a relatively undiscovered domain.

<i>Paleodictyon</i> Trace fossil

Paleodictyon is a trace fossil, usually interpreted to be a burrow, which appears in the geologic marine record beginning in the Precambrian/Early Cambrian and in modern ocean environments. Paleodictyon were first described by Giuseppe Meneghini in 1850. The origin of the trace fossil is enigmatic and numerous candidates have been proposed.

<span class="mw-page-title-main">Izu–Ogasawara Trench</span> An oceanic trench in the western Pacific, consisting of the Izu Trench and the Bonin Trench

The Izu–Ogasawara Trench, also known as Izu–Bonin Trench, is an oceanic trench in the western Pacific Ocean, consisting of the Izu Trench and the Bonin Trench.

<span class="mw-page-title-main">Porcupine Abyssal Plain</span> Stretch of seabed near Ireland

The Porcupine Abyssal Plain (PAP) is located in international waters, adjacent to the Irish continental margin. The PAP lies beyond the Porcupine Bank's deepest point and is southwest of it. It has a muddy seabed, with scattered abyssal hills that covers an area approximately half the size of Europe's landmass. Its depth ranges from 4,000 metres (13,000 ft) to 4,850 m (15,910 ft).

<i>Quinqueloculina</i> Genus of single-celled organisms

Quinqueloculina is a genus of foraminifera in the family Miliolidae.

<i>Syringammina</i> Genus of single-celled organisms

Syringammina is a xenophyophore found off the coast of Scotland, near Rockall. It is one of the largest single-celled organisms known, at up to 20 centimetres (8 in) across. It was first described in 1882 by the oceanographer John Murray, after being discovered on an expedition in the ship Triton which dredged the deep ocean bed off the west coast of Scotland in an effort to find organisms new to science. It was the first xenophyophore to be described and at first its relationship with other organisms was a mystery, but it is now considered to be a member of the Foraminifera.

<span class="mw-page-title-main">Clarion–Clipperton zone</span> Fracture zone of the Pacific Ocean seabed

The Clarion–Clipperton zone (CCZ) or Clarion–Clipperton fracture zone is an environmental management area of the Pacific Ocean, administered by the International Seabed Authority (ISA). It includes the Clarion fracture zone and the Clipperton fracture zone, geological submarine fracture zones. Clarion and Clipperton are two of the five major lineations of the northern Pacific floor, and were discovered by the Scripps Institution of Oceanography in 1954. The CCZ is regularly considered for deep-sea mining due to the abundant presence of manganese nodules.

Paleodictyon nodosum is a living creature thought to produce a certain form of burrow nearly identical to Paleodictyon fossils. The modern burrows were found around mid-ocean ridge systems in the Pacific and Atlantic Oceans. Although scientists have collected many of the burrows of Paleodictyon nodosum, they have never seen a live one. What a live specimen would look like is widely debated, with the debate being split into two main sides.

<i>Chondrites</i> (genus) Trace fossil

Chondrites is a trace fossil ichnogenus, preserved as small branching burrows of the same diameter that superficially resemble the roots of a plant. The origin of these structures is currently unknown. Chondrites is found in marine sediments from the Cambrian period of the Paleozoic onwards. It is especially common in sediments that were deposited in reduced-oxygen environments.

Stercomata are extracellular pellets of waste material produced by some groups of foraminiferans, including xenophyophoreans and komokiaceans, Gromia, and testate amoebae. The pellets are ovoid (egg-shaped), brownish in color, and on average measure from 10-20 μm in length. Stercomata are composed of small mineral grains and undigested waste products held together by strands of glycosaminoglycans.

Madeira Abyssal Plain, also called Madeira Plain, is an abyssal plain situated at the center and deepest part of the Canary Basin. It is a north-northeast to south-southeast elongated basin that almost parallels the Mid-Atlantic Ridge. Its western boundary is marked by a chain of seamounts known as the either Seewarte Seamounts or Atlantis-Great Meteor Seamount Chain. Its eastern boundary is a distinct break of slope that marks the foot of the African Continental Rise. This abyssal plain occupies an area of about 68,000 km2 (26,000 sq mi). Across this basin, slope angles are generally less than 0.01°.

<span class="mw-page-title-main">Foraminifera test</span> Shell of a particular type of protist

Foraminiferal tests are the tests of Foraminifera.

<span class="mw-page-title-main">Protists in the fossil record</span>

A protist is any eukaryotic organism that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor, the last eukaryotic common ancestor, the exclusion of other eukaryotes means that protists do not form a natural group, or clade. Therefore, some protists may be more closely related to animals, plants, or fungi than they are to other protists. However, like algae, invertebrates and protozoans, the grouping is used for convenience.

References

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  2. 1 2 3 4 5 6 Levin, Lisa A. (February 1994). "Paleoecology and Ecology of Xenophyophores". PALAIOS. 9 (1): 32–41. doi:10.2307/3515076. JSTOR   3515076.
  3. Gooday, Andrew J.; Holzmann, Maria; Caulle, Clémence; Goineau, Aurélie; Kamenskaya, Olga; Weber, Alexandra A.-T.; Pawlowski, Jan (2017-03-01). "Giant protists (xenophyophores, Foraminifera) are exceptionally diverse in parts of the abyssal eastern Pacific licensed for polymetallic nodule exploration". Biological Conservation. 207: 106–116. doi: 10.1016/j.biocon.2017.01.006 . ISSN   0006-3207.
  4. 1 2 Gooday, A. J. (1991-07-01). "Xenophyophores (Protista, Rhizopoda) in box-core samples from the abyssal Northeast Atlantic Ocean, BIOTRANS area; their taxonomy, morphology, and ecology". The Journal of Foraminiferal Research. 21 (3): 197–212. doi:10.2113/gsjfr.21.3.197. ISSN   0096-1191.
  5. 1 2 Gooday, Andrew J.; Holzmann, Maria; Goineau, Aurélie; Pearce, Richard B.; Voltski, Ivan; Weber, Alexandra A.-T.; Pawlowski, Jan (2018-08-03). "Five new species and two new genera of xenophyophores (Foraminifera: Rhizaria) from part of the abyssal equatorial Pacific licensed for polymetallic nodule exploration". Zoological Journal of the Linnean Society. 183 (4): 723–748. doi: 10.1093/zoolinnean/zlx093 . ISSN   0024-4082.
  6. Swinbanks, David D.; Shirayama, Yoshihisa (March 1986). "High levels of natural radionuclides in a deep-sea infaunal xenophyophore". Nature. 320 (6060): 354–358. doi:10.1038/320354a0. ISSN   0028-0836. S2CID   4254138.
  7. Rona, Peter A.; Seilacher, Adolf; de Vargas, Colomban; Gooday, Andrew J.; Bernhard, Joan M.; Bowser, Sam; Vetriani, Costantino; Wirsen, Carl O.; Mullineaux, Lauren; Sherrell, Robert; Frederick Grassle, J. (September 2009). "Paleodictyon nodosum: A living fossil on the deep-sea floor". Deep Sea Research Part II: Topical Studies in Oceanography. 56 (19–20): 1700–1712. doi:10.1016/j.dsr2.2009.05.015. ISSN   0967-0645.