Gromia sphaerica

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Gromia sphaerica
Gromia in situ closeup.png
Close-up of Gromia in place. Note the particles of sand and muck stuck to the surface.
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Phylum: Endomyxa
Class: Gromiidea
Order: Gromiida
Family: Gromiidae
Genus: Gromia
Species:
G. sphaerica
Binomial name
Gromia sphaerica
Gooday, Bowser, Bett & Smith 2000

Gromia sphaerica is a large spherical testate amoeba, a single-celled eukaryotic organism and the largest of its genus, Gromia . The genus itself contains about 13 known species, 3 of which were discovered as late as 2005. [1] It was discovered in 2000, along the Oman margin of the Arabian Sea, at depths around 1,163 to 1,194 meters (3,816 to 3,917 ft). Specimens range in size from 4.7 to 38 millimeters (0.19 to 1.50 inches) in diameter. The test (organic shell) is usually spherical in shape and honeycombed with pores. There are filaments on the bottom of the organism, where it is in contact with the seafloor, and it is mostly filled with stercomata (waste pellets). [2]

Contents

In 2008, 30-millimeter (1.2-inch) specimens were found off the coast of Little San Salvador in the Bahamas by researchers from the University of Texas. These Gromia were discovered to make mud trails as much as 50 centimeters (20 inches) in length. It was previously thought that single-celled organisms were incapable of making these kinds of trails, and their cause was previously a source of speculation. The mud trails made by the Bahamian Gromia appear to match prehistoric mud trails from the Precambrian, including 1.8 billion year-old fossil trails in the Stirling formation in Australia. [3] [4] [5] [6] Because the tracks of Gromia resemble the 1.8 billion year old traces that were believed to represent the traces of complex bilaterian worms, said tracks could have been a result of similarly giant single-celled organisms instead of complex animals.

Description

Gromia sphaerica mainly resembled a grape in size and in body appearance. When the sediment was removed from one of the specimens, it showed that the skin was similar to that of a grape's skin, but much softer when touched. [7]

Tracks

The tracks that G. sphaerica makes on the muddy sea floor are similar to the tracks of animals from the Ediacaran period. In some of the photos, the tracks can be seen as being curved. [8]

Related Research Articles

<i>Kimberella</i> Primitive Mollusc-like organism

Kimberella is an extinct genus of bilaterian known only from rocks of the Ediacaran period. The slug-like organism fed by scratching the microbial surface on which it dwelt in a manner similar to the gastropods, although its affinity with this group is contentious.

<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">Marine life</span> Organisms that live in salt water

Marine life, sea life, or ocean life is the plants, animals, and other organisms that live in the salt water of seas or oceans, or the brackish water of coastal estuaries. At a fundamental level, marine life affects the nature of the planet. Marine organisms, mostly microorganisms, produce oxygen and sequester carbon. Marine life, in part, shape and protect shorelines, and some marine organisms even help create new land.

<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">Vendobionta</span> Group of extinct creatures that were part of the Ediacaran biota

Vendobionts or Vendozoans (Vendobionta) are a proposed very high-level, extinct clade of benthic organisms that made up of the majority of the organisms that were part of the Ediacaran biota. It is a hypothetical group and at the same time, it would be the oldest of the animals that populated the Earth about 580 million years ago, in the Ediacaran period. They became extinct shortly after the so-called Cambrian explosion, with the introduction of fauna forming groups more recognizably related to modern animals. It is very likely that the whole Ediacaran biota is not a monophyletic clade and not every genus placed in its subtaxa is an animal.

<span class="mw-page-title-main">Ediacaran biota</span> Life of the Ediacaran period

The Ediacaranbiota is a taxonomic period classification that consists of all life forms that were present on Earth during the Ediacaran Period. These were enigmatic tubular and frond-shaped, mostly sessile, organisms. Trace fossils of these organisms have been found worldwide, and represent the earliest known complex multicellular organisms. The term "Ediacara biota" has received criticism from some scientists due to its alleged inconsistency, arbitrary exclusion of certain fossils, and inability to be precisely defined.

<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">Marine invertebrates</span> Marine animals without a vertebral column

Marine invertebrates are the invertebrates that live in marine habitats. Invertebrate is a blanket term that includes all animals apart from the vertebrate members of the chordate phylum. Invertebrates lack a vertebral column, and some have evolved a shell or a hard exoskeleton. As on land and in the air, marine invertebrates have a large variety of body plans, and have been categorised into over 30 phyla. They make up most of the macroscopic life in the oceans.

<span class="mw-page-title-main">Testate amoebae</span>

Testate amoebae are a polyphyletic group of unicellular amoeboid protists, which differ from naked amoebae in the presence of a test that partially encloses the cell, with an aperture from which the pseudopodia emerge, that provides the amoeba with shelter from predators and environmental conditions.

<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">Marine microorganisms</span> Any life form too small for the naked human eye to see that lives in a marine environment

Marine microorganisms are defined by their habitat as microorganisms living in a marine environment, that is, in the saltwater of a sea or ocean or the brackish water of a coastal estuary. A microorganism is any microscopic living organism or virus, which is invisibly small to the unaided human eye without magnification. Microorganisms are very diverse. They can be single-celled or multicellular and include bacteria, archaea, viruses, and most protozoa, as well as some fungi, algae, and animals, such as rotifers and copepods. Many macroscopic animals and plants have microscopic juvenile stages. Some microbiologists also classify viruses as microorganisms, but others consider these as non-living.

<i>Dendrogramma</i> Genus of animals belonging to cnidarians and described in 2014

Dendrogramma enigmatica is a species of siphonophore, the only one in its genus. It has been first described in 2014 on the basis of its morphology from a collection of specimens gathered in 1986. Its taxonomic affinity among animals was then unclear, but RNA from new specimens in 2016 allowed it to be identified as a siphonophore by barcoding and phylogenomics. The specimens are presumed to represent parts (bracts) of an entire siphonophore that has not been identified yet.

<span class="mw-page-title-main">Amoeba</span> Cellular body type

An amoeba, often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudopods. Amoebae do not form a single taxonomic group; instead, they are found in every major lineage of eukaryotic organisms. Amoeboid cells occur not only among the protozoa, but also in fungi, algae, and animals.

<span class="mw-page-title-main">Choanozoa</span> Clade of opisthokont eukaryotes consisting of the choanoflagellates and the animals

Choanozoa is a clade of opisthokont eukaryotes consisting of the choanoflagellates (Choanoflagellatea) and the animals. The sister-group relationship between the choanoflagellates and animals has important implications for the origin of the animals. The clade was identified in 2015 by Graham Budd and Sören Jensen, who used the name Apoikozoa. The 2018 revision of the classification first proposed by the International Society of Protistologists in 2012 recommends the use of the name Choanozoa.

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.

<span class="mw-page-title-main">Marine protists</span> Protists that live in saltwater or brackish water

Marine protists are defined by their habitat as protists that live in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. Life originated as marine single-celled prokaryotes and later evolved into more complex eukaryotes. Eukaryotes are the more developed life forms known as plants, animals, fungi and protists. Protists are the eukaryotes that cannot be classified as plants, fungi or animals. They are mostly single-celled and microscopic. The term protist came into use historically as a term of convenience for eukaryotes that cannot be strictly classified as plants, animals or fungi. They are not a part of modern cladistics because they are paraphyletic.

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

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.

References

  1. Rothe, Nina; Gooday, Andrew J.; Cedhagen, Tomas; Fahrni, José; Hughes, J. Alan; Page, Anton; Pearce, Richard B.; Pawlowski, JAN (2009). "Three new species of deep-sea Gromia (Protista, Rhizaria) from the bathyal and abyssal Weddell Sea, Antarctica". Zoological Journal of the Linnean Society. 157 (3): 451–469. doi: 10.1111/j.1096-3642.2009.00540.x .
  2. Gooday, Andrew J; Bowser, Samuel S; Bett, Brian J; Smith, Craig R (January 2000). "A large testate protist, Gromia sphaerica sp. nov. (Order Filosea), from the bathyal Arabian Sea". Deep Sea Research Part II: Topical Studies in Oceanography. 47 (1–2): 55–73. Bibcode:2000DSRII..47...55G. doi:10.1016/S0967-0645(99)00100-9. Archived from the original on 2012-05-31. Retrieved 2008-11-20 via Centre National de la Recherche Scientifique.
  3. Matz, Mikhail V.; Tamara M. Frank; N. Justin Marshall; Edith A. Widder; Sonke Johnsen (2008-12-09). "Giant Deep-Sea Protist Produces Bilaterian-like Traces" (PDF). Current Biology. 18 (23). Elsevier Ltd: 1849–1854. doi: 10.1016/j.cub.2008.10.028 . PMID   19026540. S2CID   8819675 . Retrieved 2008-12-05.
  4. Reilly, Michael (2008-11-20). "Single-celled giant upends early evolution". NBC News. Retrieved 2008-12-05.
  5. "Discovery of Giant Roaming Deep Sea Protist Provides New Perspective on Animal Evolution". University of Texas at Austin College of Natural Sciences. 2008-11-20. Archived from the original on 2019-07-21. Retrieved 2019-07-21.
  6. "Rolling 'Sea Grape' Rocks The Fossil Record". ScienceDaily. 2008-12-04. Retrieved 2018-07-24.
  7. "Sinh vật đơn bào thay đổi cách nhìn về tiến hóa - KhoaHoc.tv".
  8. "Figure 1. Tracks of the Bahamian Gromia sphaerica (A) Gently sloping".