iXenophyophores
Xenophyophore in the Galapagos Rift
Scientific classification
Kingdom: Protista Phylum: Foraminifera? Class: Xenophyophorea
Orders
Psamminida Stannomida Xenophyophore in the Galapagos Rift, from NOAAs Ocean Explorer. ... Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Typical phyla Chromista Heterokontophyta Haptophyta Cryptophyta (cryptomonads) Alveolata Dinoflagellata Apicomplexa Ciliophora (ciliates) Excavata Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Archaeplastida (in part) Rhodophyta (red algae) Glaucophyta (basal archaeplastids) Amoebozoa Choanozoa Many others; classification varies Protists (IPA: ) are a heterogeneous group of organisms, comprising those eukaryotes that are not animals... Orders Allogromiida Carterinida Fusulinida - extinct Globigerinida Involutinida - extinct Lagenida Miliolida Robertinida Rotaliida Silicoloculinida Spirillinida Textulariida incertae sedis    Xenophyophorea    Reticulomyxa The Foraminifera, or forams for short, are a large group of amoeboid protists with reticulating pseudopods, fine strands that branch and merge to form a dynamic net. ...

Xenophyophores are marine protozoans, giant single-celled organisms found throughout the world's oceans, but in their greatest numbers on the abyssal plains of the deep ocean. They were first described as sponges in 1889, then as testate amoeboids, and later as their own phylum of Protista. A recent genetic study suggested that the xenophyophores are a specialized group of Foraminifera. There are approximately 42 recognized species in 13 genera and 2 orders; one of which, Syringammina fragillissima, is among the largest known protozoans at a maximum 20 centimetres in diameter. Wikisource has an original article from the 1911 Encyclopædia Britannica about: Protozoa Protozoa (in Greek proto = first and zoa = animals) are single-celled eukaryotes (organisms whose cells have nuclei) that commonly show characteristics usually associated with animals, most notably mobility and heterotrophy. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ... Abyssal plains are flat or very gently sloping areas of the deep ocean basin floor. ... Classes Calcarea Hexactinellida Demospongiae The sponges or poriferans (from the Greek poros pore and ferro to bear) are animals of the phylum Porifera. ... 1889 (MDCCCLXXXIX) was a common year starting on Tuesday (see link for calendar). ... Amoeba (Chaos diffluens) Foraminiferan (Ammonia tepida) Heliozoan (Actinophrys sol) Amoeboids are cells that move or feed by means of temporary projections, called pseudopods (false feet). ... Typical phyla Chromista Heterokontophyta Haptophyta Cryptophyta (cryptomonads) Alveolata Dinoflagellata Apicomplexa Ciliophora (ciliates) Excavata Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Archaeplastida (in part) Rhodophyta (red algae) Glaucophyta (basal archaeplastids) Amoebozoa Choanozoa Many others; classification varies Protists (IPA: ) are a heterogeneous group of organisms, comprising those eukaryotes that are not animals... Orders Allogromiida Carterinida Fusulinida - extinct Globigerinida Involutinida - extinct Lagenida Miliolida Robertinida Rotaliida Silicoloculinida Spirillinida Textulariida incertae sedis    Xenophyophorea    Reticulomyxa The Foraminifera, or forams for short, are a large group of amoeboid protists with reticulating pseudopods, fine strands that branch and merge to form a dynamic net. ... A centimetre (American spelling centimeter, symbol cm) is a unit of length that is equal to one hundredth of a metre, the current SI base unit of length. ...

Abundant but poorly understood, xenophyophores are delicate organisms with a variable appearance; some may resemble flattened discs, angular four-sided shapes (tetrahedra), or like frilly or spherical sponges. Local environmental conditions—such as current direction and speed—may play a part in influencing these forms. Xenophyophores are essentially lumps of viscous fluid called cytoplasm containing numerous nuclei distributed evenly throughout. Everything is contained in a ramose system of tubes called a granellare, itself composed of an organic cement-like substance. Organelles. ... The eukaryotic cell nucleus. ...

As benthic deposit feeders, xenophyophores tirelessly root through the muddy sediments on the sea floor. They excrete a slimy substance whilst feeding; in locations with a dense population of xenophyophores, such as at the bottoms of oceanic trenches, this slime may cover large areas. Local population densities may be as high as 2,000 individuals per 100 square meters, making them dominant organisms in some areas. These giant protozoans seem to feed in a manner similar to amoebas, enveloping food items with a foot-like structure called a pseudopodium. Most are epifaunal (living atop the seabed), but one species (Occultammina profunda), is known to be infaunal; it buries itself up to 6 cm deep into the sediment. In oceanography, marine geology and biology, benthos are the organisms and habitats of the sea floor; in freshwater biology they are the organisms and habitats of the bottoms of lakes, rivers, and creeks. ... Pseudopods or pseudopodia (false feet) are temporary projections of eukaryotic cells. ...

Their glue-like secretions cause silt and strings of their own fecal matter, called stercomes, to build up into masses (called stercomares) on their exteriors. In this way, the organisms form structures which project from the sea floor; this characteristic also explains their name, which may be translated from the Greek to mean "bearer of foreign bodies". A protective, shell-like test is thereby agglutinated around the granellare, which is composed of scavenged minerals and the microscopic skeletal remains of other organisms, such as sponges, radiolarians, and other foraminiferans. Minerals are natural compounds formed through geological processes. ... Classes Polycystinea Acantharea Sticholonchea Radiolarians (also radiolaria) are amoeboid protozoa that produce intricate mineral skeletons, typically with a central capsule dividing the cell into inner and outer portions, called endoplasm and ectoplasm. ...

Xenophyophores may be an important part of the benthic ecosystem by virtue of their constant bioturbation of the sediments, providing a habitat for other organisms such as isopods. Research has shown that areas dominated by xenophyophores have 3-4 times the number of benthic crustaceans, echinoderms, and molluscs than equivalent areas which lack xenophyophores. The xenophyophores themselves also play commensal host to a number of organisms—such as isopods (e.g., genus Hebefustis), sipunculan and polychaete worms, nematodes, and harpacticoid copepods—some of which may take up semi-permanent residence within a xenophyophore's test. Brittle stars (Ophiuroidea) also appear to have some sort of relationship with xenophyophores, as they are consistently found directly underneath or on top of the protozoans. In oceanography and limnology, the displacement and mixing of sediment particles by benthic fauna (animals) or flora (plants) is termed bioturbation. ... SubOrders Anthuridea Asellota Calabozoida Epicaridea Flabellifera Microcerberidea Oniscidea Phreatoicidea Valvifera Isopods are one of the most diverse orders of Crustaceans, with many species living in all environments, and are common in shallow marine waters. ... Classes Remipedia Cephalocarida Branchiopoda Ostracoda Maxillopoda Malacostraca The crustaceans (Crustacea) are a large group of arthropods (55,000 species), usually treated as a subphylum. ... Classes Asteroidea Blastoidea (extinct) Concentricycloidea Crinoidea Echinoidea Holothuroidea Ophiuroidea Echinoderms (Phylum Echinodermata, from the Greek for spiny skin) are a phylum of marine animals found at all depths. ... Classes Caudofoveata Aplacophora Polyplacophora - Chitons Monoplacophora Bivalvia - Bivalves Scaphopoda - Tusk shells Gastropoda - Snails and Slugs Cephalopoda - Squids, Octopuses, etc. ... Commensalism is an interaction between two living organisms, where one organism benefits and the other is neither harmed nor helped. ... The Sipuncula, sipunculid worms or peanut worms, are a phylum of marine worms with a tentacle surrounded mouth on a completely invertible head end. ... Orders Amphinomida Capitellida Chaetopterida Cirratulida Cossurida Ctenodrillidae Eunicida Flabelligerida Magelonida Myzostomida Nerillida Opheliida Orbiniida Orweniida Phyllodocida Pisionidae Polygordiida Protodrilida Psammodrilidae Sabellida Spionida Spintheridae Sternaspida Terebellida Tomopteris from plankton The Polychaeta or Polychaetes are a class of annelid worms, generally marine, with a pair of fleshy protrusions on each body segment... Classes Adenophorea    Subclass Enoplia    Subclass Chromadoria Secernentea    Subclass Rhabditia    Subclass Spiruria    Subclass Diplogasteria The nematodes or roundworms (Phylum Nematoda from Greek νῆμα (nema): thread + ode like) are one of the most common phyla of animals, with over 20,000 different described species (over 15,000 are parasitic). ... Families There are 54 families: Adenopleurellidae Aegisthidae Ambunguipedidae Ameiridae Ancorabolidae Argestidae Balaenophilidae Cancrincolidae Canthocamptidae Canuellidae Cerviniidae Chappuisiidae Cletodidae Cletopsyllidae Clytemnestridae Cristacoxidae Cylindropsyllidae Darcythompsoniidae Diosaccidae Ectinosomatidae Euterpinidae Hamondiidae Harpacticidae Huntemanniidae Laophontidae Laophontopsidae Latiremidae Leptastacidae Leptopontiidae Longipediidae Louriniidae Metidae Miraciidae Neobradyidae Normanellidae Novocriniidae Orthopsyllidae Paramesochridae Parastenheliidae Parastenocarididae Peltidiidae Phyllognathopodidae Porcellidiidae Pseudotachidiidae Rhizothricidae... Orders Calanoida Cyclopoida Gelyelloida Harpacticoida Misophrioida Monstrilloida Mormonilloida Platycopioida Poecilostomatoida Siphonostomatoida Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. ... Orders Oegophiurida Ophiurida Phrynophiurida Brittle starfishs are echinoderms, closely related to sea stars. ...

Xenophyophores are difficult to study due to their extreme fragility. Specimens are invariably damaged during sampling, rendering them useless for captive study or cell culture. For this reason, very little is known of their life history. As they occur in all the world's oceans and in great numbers, xenophyophores could be indispensable agents in the process of sediment deposition and in maintaining biological diversity in benthic ecosystems. Epithelial cells in culture, stained for keratin (red) and DNA (green) Cell culture is the term applied when cells are grown in a synthetic environment. ... Biodiversity or biological diversity is a neologism and a portmanteau word, from bio and diversity. ...

References

• Gubbay, S., Baker, M., Bettn, B., Konnecker, G. (2002). "The offshore directory: Review of a selection of habitats, communities and species of the north-east Atlantic", pp. 74–77. Retrieved July 15, 2005.
• NOAA Ocean Explorer. "Windows to the deep exploration: Giants of the protozoa", p. 2. Retrieved July 15, 2005
• Pawlowski J, Holzmann M, Fahrni J, Richardson SL. (2003). Small subunit ribosomal DNA suggests that the xenophyophorean Syringamma corbicula is a foraminiferan. Journal of Eukaryotic Microbiology 50(6): 483-7.

The National Oceanic and Atmospheric Administration (NOAA) is a scientific agency of the United States Department of Commerce focused on the conditions of the oceans and the atmosphere. ...

External links

• Microscopy-UK: Note on Xenophyophores
• More xenophyophore photos, with a map of their habitat