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Encyclopedia > Diatom
Wikipedia:How to read a taxobox
How to read a taxobox
Diatoms
Marine diatoms
Marine diatoms
Scientific classification
Domain: Eukaryota
Kingdom: Chromalveolata
Phylum: Heterokontophyta
Class: Bacillariophyceae
Orders

Diatoms (Greek: διά (dia) = "through" + τέμνειν (temnein) = "to cut", i.e., "cut in half") are a major group of eukaryotic algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although some form chains or simple colonies. A characteristic feature of diatom cells is that they are encased within a unique cell wall made of silica (hydrated silicon dioxide). These walls show a wide diversity in form, some quite beautiful and ornate, but usually consist of two asymmetrical sides with a split between them, hence the group name. Fossil evidence suggests that they originated during, or before, the early Jurassic Period. Image File history File links Beautiful marine diatoms as seen through a microscope. ... Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista Alternative Phylogeny Unikonta    Opisthokonta    Amoebozoa Bikonta    Apusozoa    Cabozoa       Rhizaria       Excavata    Corticata       Archaeplastida       Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms with a complex cell or cells, where the genetic material is organized into a membrane-bound nucleus or nuclei. ... The chromalveolates (Chromalveolata) are a hypothetical grouping of eukaryotes, comprising the Chromista and alveolates, as suggested by Tom Cavalier-Smith. ... Typical classes Colored groups Chrysophyceae (golden algae) Synurophyceae Actinochrysophyceae (axodines) Pelagophyceae Phaeothamniophyceae Bacillariophyceae (diatoms) Bolidophyceae Raphidophyceae Eustigmatophyceae Xanthophyceae (yellow-green algae) Phaeophyceae (brown algae) Colorless groups Oomycetes (water moulds) Hypochytridiomycetes Bicosoecea Labyrinthulomycetes (slime nets) Opalinea Proteromonadea The heterokonts or stramenopiles are a major line of eukaryotes containing about 10,500... In scientific classification used in biology, the order (Latin: ordo, plural ordines) is a rank between class and family (termed a taxon at that rank). ... Order Centrales is a traditional subdivision of the heterokont algae known as diatoms[1][2]. The order is named for the shape of the cell walls (or valves or frustules) of centric diatoms, which are circular or ellipsoid in valve view. ... Order Pennales is a traditional subdivision of the heterokont algae known as diatoms[1][2]. The order is named for the shape of the cell walls (or valves or frustules) of pennate diatoms, which are elongated in valve view. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista Alternative Phylogeny Unikonta    Opisthokonta    Amoebozoa Bikonta    Apusozoa    Cabozoa       Rhizaria       Excavata    Corticata       Archaeplastida       Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms with a complex cell or cells, where the genetic material is organized into a membrane-bound nucleus or nuclei. ... A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ... Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of the plankton that drift in the water column. ... A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ... In biology, a colony (from Latin colonia) means several individual organisms of the same species living closely together, usually for mutual benefit, such as stronger defences, the ability to attack bigger prey etc. ... The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ... Three small ammonite fossils, each approximately 1. ... The Jurassic Period is a major unit of the geologic timescale that extends from about 199. ... A geologic period is a subdivision of geologic time that divides an era into smaller timeframes. ...

Contents

General biology

An assortment of Diatomea from Ernst Haeckel's 1904 Kunstformen der Natur (Artforms of Nature)
An assortment of Diatomea from Ernst Haeckel's 1904 Kunstformen der Natur (Artforms of Nature)

There are more than 200 genera of living diatoms, and it is estimated that there are approximately 100,000 extant species[1]. Diatoms are a widespread group and can be found in the oceans, in freshwater, in soils and on damp surfaces. Most live pelagically in open water, although some live as surface films at the water-sediment interface (benthic), or even under damp atmospheric conditions. They are especially important in oceans, where they are estimated to contribute up to 45% of the total oceanic primary production[2]. Although usually microscopic, some species of diatoms can reach up to 2 millimetres in length. Image File history File links Download high resolution version (2327x3276, 2086 KB) Summary The 84th plate from Ernst Haeckels Kunstformen der Natur (1904), depicting diatoms (Diatomea). ... Image File history File links Download high resolution version (2327x3276, 2086 KB) Summary The 84th plate from Ernst Haeckels Kunstformen der Natur (1904), depicting diatoms (Diatomea). ... Ernst Haeckel. ... For other uses of the word, please see Genus (disambiguation). ... Extant means still existing. It is the opposite of extinct, and can be applied to species, cultures and works of culture (e. ... In biology, a species is one of the basic units of biodiversity. ... Animated map exhibiting the worlds oceanic waters. ... For the village on the Isle of Wight, see Freshwater, Isle of Wight. ... Loess field in Germany Surface-water-gley developed in glacial till, Northern Ireland Soil comprising the pedosphere is positioned at the interface of the lithosphere and biosphere with the atmosphere and hydrosphere. ... The pelagic zone is the part of the open sea or ocean comprising the water column, i. ... 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. ... To meet Wikipedias quality standards and make it easier to understand, this article or section may require cleanup. ... Robert Hookes microscope (1665) - an engineered device used to study living systems. ... A millimetre (American spelling: millimeter, symbol mm) is an SI unit of length that is equal to one thousandth of a metre. ...


Diatoms belong to a large group called the heterokonts, including both autotrophs (e.g. golden algae, kelp) and heterotrophs (e.g. water moulds). Their yellowish-brown chloroplasts are typical of heterokonts, with four membranes and containing pigments such as fucoxanthin. Individuals usually lack flagella, but they are present in gametes and have the usual heterokont structure, except they lack the hairs (mastigonemes) characteristic in other groups. Typical classes Colored groups Chrysophyceae (golden algae) Synurophyceae Actinochrysophyceae (axodines) Pelagophyceae Phaeothamniophyceae Bacillariophyceae (diatoms) Bolidophyceae Raphidophyceae Eustigmatophyceae Xanthophyceae (yellow-green algae) Phaeophyceae (brown algae) Colorless groups Oomycetes (water moulds) Hypochytridiomycetes Bicosoecea Labyrinthulomycetes (slime nets) Opalinea Proteromonadea The heterokonts or stramenopiles are a major line of eukaryotes containing about 10,500... This article or section does not adequately cite its references or sources. ... The golden algae or chrysophytes are a large group of heterokont algae, found mostly in freshwater. ... Families Alariaceae Chordaceae Laminariaceae Lessoniaceae Phyllariaceae Pseudochordaceae Kelp are large seaweeds (algae), belonging to the brown algae and classified in the order Laminariales. ... Flowchart to determine if a species is autotroph, heterotroph, or a subtype A heterotroph (Greek heterone = (an)other and trophe = nutrition) is an organism that requires organic substrates to get its carbon for growth and development. ... Orders Lagenidiales Leptomitales Peronosporales Pythiales Rhipidiales Saprolegniales Sclerosporales Water moulds or Oomycetes are a group of filamentous protists, physically resembling fungi. ... Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ... The monarch butterflys distinctive pigmentation reminds potential predators that it is poisonous. ... Fucoxanthin Fucoxanthin is a carotenoid, with formula C40H60O6. ... // A Flagellum (plural: flagella) is a long, slender projection from the cell body, composed of microtubules and surrounded by the plasma membrane. ... A gamete is a specialized germ cell that fuses with another gamete during fertilization (conception) in organisms that reproduce sexually. ...


Most diatom species are non-motile but some are capable of an oozing motion. As their relatively dense cell walls cause them to readily sink, planktonic forms in open water usually rely on turbulent mixing of the upper layers by the wind to keep them suspended in sunlit surface waters. Some species actively regulate their buoyancy with intracellular lipids to counter sinking. Motility is a biological term which refers to the ability to move spontaneously and independently. ... In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by chaotic, stochastic property changes. ... This article or section does not adequately cite its references or sources. ... A polyunsaturated triglyceride. ...


Diatoms cells are contained within a unique silicate (silicic acid) cell wall comprised of two separate valves (or shells). The biogenic silica that the cell wall is composed of is synthesised intracellularly by the polymerisation of silicic acid monomers. This material is then extruded to the cell exterior and added to the wall. Diatom cell walls are also called frustules or tests, and their two valves typically overlap one other like the two halves of a petri dish. In most species, when a diatom divides to produce two daughter cells, each cell keeps one of the two valves and grows a smaller valve within it. As a result, after each division cycle the average size of diatom cells in the population gets smaller. Once such cells reach a certain minimum size, rather than simply divide vegetatively, they reverse this decline by forming an auxospore. This expands in size to give rise to a much larger cell, which then returns to size-diminishing divisions. Auxospore production is almost always linked to meiosis and sexual reproduction. Silicic acid is a general name for a family of chemical compounds of silicon, hydrogen, and oxygen, with the general formula [SiOx(OH)4-2x]n. ... A cell wall is a fairly rigid layer surrounding a cell, located external to the cell membrane, that provides the cell with structural support, protection, and a filtering mechanism. ... In cell biology, molecular biology and related fields, the word intracellular means inside the cell. It is used in contrast to extracellular (outside the cell). ... Polymerization is the formation of long, repeating organic polymer chains. ... In chemistry, a monomer (from Greek mono one and meros part) is a small molecule that may become chemically bonded to other monomers to form a polymer. ... Man looking at fungus inside of petri dishes A Petri dish is a shallow glass or plastic cylindrical dish that biologists use to culture microbes. ... Production of new individuals along a leaf margin of the air plant, Kalanchoë pinnata. ... In phycology, auxospores are special cells produced by diatoms that expand cell size back to that which is normal for vegetative cells[1]. They are necessary because successive mitotic cell divisions in diatoms leads to a diminuation in cell size. ... Not to be confused with miosis. ...


Decomposition and decay of diatoms leads to organic and inorganic (in the form of silicates) sediment, the inorganic component of which can lead to a method of analyzing past marine environments by corings of ocean floors or bay muds, since the inorganic matter is embedded in deposition of clays and silts and forms a permanent geological record of such marine strata. Organic has several meanings and related topics. ... Inorganic chemistry is the branch of chemistry concerned with the properties and reactions of inorganic compounds. ... In chemistry, a silicate is a compound containing an anion in which one or more central silicon atoms are surrounded by electronegative ligands. ... Richardson Bay mudflats of are exposed layers of bay mud Bay mud consists of thick deposits of soft, unconsolidated silty clay, which is saturated with water; these soil layers are situated at the bottom of certain estuaries, which are normally in temperate regions that have experienced cyclical glacial cycles. ... The Gay Head cliffs in Marthas Vineyard are made almost entirely of clay. ... Silt is soil or rock derived granular material of a specific grain size. ... Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. ...


Classification

The classification of heterokonts is still unsettled, and they may be treated as a division (or phylum), kingdom, or something in-between. Accordingly, groups like the diatoms may be ranked anywhere from class (usually called Bacillariophyceae) to division (usually called Bacillariophyta), with corresponding changes in the ranks of their subgroups. The diatoms are also sometimes referred to as Class Diatomophyceae. In biology, the equivalent of a phylum in the plant or fungi kingdom is called a division. ... Phylum (plural: phyla) is a taxon used in the classification of animals, adopted from the Greek phylai the clan-based voting groups in Greek city-states. ... Ernst Haeckels presentation of a three-kingdom system (Plantae, Protista, Animalia) in his 1866 Generelle Morphologie der Organismen). ...


Diatoms are traditionally divided into two orders: centric diatoms (Centrales), which are radially symmetric, and pennate diatoms (Pennales), which are bilaterally symmetric. The former are paraphyletic to the latter. A more recent classification[1] divides the diatoms into three classes: centric diatoms (Coscinodiscophyceae), pennate diatoms without a raphe (Fragilariophyceae), and pennate diatoms with a raphe (Bacillariophyceae). It is probable there will be further revisions as understanding of their relationships increases. In scientific classification used in biology, the order (Latin: ordo, plural ordines) is a rank between class and family (termed a taxon at that rank). ... Order Centrales is a traditional subdivision of the heterokont algae known as diatoms[1][2]. The order is named for the shape of the cell walls (or valves or frustules) of centric diatoms, which are circular or ellipsoid in valve view. ... Sphere symmetry group o. ... Order Pennales is a traditional subdivision of the heterokont algae known as diatoms[1][2]. The order is named for the shape of the cell walls (or valves or frustules) of pennate diatoms, which are elongated in valve view. ... Paraphyletic - Wikipedia /**/ @import /skins-1. ... Order Centrales is a traditional subdivision of the heterokont algae known as diatoms[1][2]. The order is named for the shape of the cell walls (or valves or frustules) of centric diatoms, which are circular or ellipsoid in valve view. ... This page is a candidate for speedy deletion, because: it is patent nonsense. ... Order Pennales is a traditional subdivision of the heterokont algae known as diatoms[1][2]. The order is named for the shape of the cell walls (or valves or frustules) of pennate diatoms, which are elongated in valve view. ... Diatoms are the most common of the eukaryotic algae. ...


Round & Crawford (1990)[1] and Hoek et al. (1995)[3] provide more comprehensive coverage of diatom taxonomy.


Ecology

A budget of the ocean's silicon cycle
A budget of the ocean's silicon cycle[4]

Planktonic forms in freshwater and marine environments typically exhibit a "boom and bust" (or "bloom and bust") lifestyle. When conditions in the upper mixed layer (nutrients and light) are favourable (e.g. at the start of spring) their competitive edge[5] allows them to quickly dominate phytoplankton communities ("boom" or "bloom"). As such they are often classed as opportunistic r-strategists (i.e. those organisms whose ecology is defined by a high growth rate, r). Image File history File links Oceanic_Silicon_Cycle_Budget. ... Image File history File links Oceanic_Silicon_Cycle_Budget. ... Photomontage of plankton organisms Plankton are any drifting organism that inhabits the water column of oceans, seas, and bodies of fresh water. ... In economics, the term boom and bust refers to the movement of an economy through economic cycles due to changes in aggregate demand. ... In ecology, r-selection (note: lower case r) relates to the selection of traits (in organisms) that allow success in unstable or unpredictable environments. ...


When conditions turn unfavourable, usually upon depletion of nutrients, diatom cells typically increase in sinking rate and exit the upper mixed layer ("bust"). This sinking is induced by either a loss of buoyancy control, the synthesis of mucilage that sticks diatoms cells together, or the production of heavy resting spores. Sinking out of the upper mixed layer removes diatoms from conditions inimical to growth, including grazer populations and higher temperatures (which would otherwise increase cell metabolism). Cells reaching deeper water or the shallow seafloor can then rest until conditions become more favourable again. In the open ocean, many sinking cells are lost to the deep, but refuge populations can persist near the thermocline. Mucilage is a thick gluey substance, often produced by plants. ... A few of the metabolic pathways in a cell. ... The thermocline is a layer within a body of water where the temperature changes rapidly with depth. ...


Ultimately, diatom cells in these resting populations re-enter the upper mixed layer when vertical mixing entrains them. In most circumstances, this mixing also replenishes nutrients in the upper mixed layer, setting the scene for the next round of diatom blooms. In the open ocean (away from areas of continuous upwelling[6]), this cycle of bloom, bust, then return to pre-bloom conditions typically occurs over an annual cycle, with diatoms only being prevalent during the spring and early summer. In some locations, however, an autumn bloom may occur, caused by the breakdown of summer stratification and the entrainment of nutrients while light levels are still sufficient for growth. Since vertical mixing is increasing, and light levels are falling as winter approaches, these blooms are smaller and shorter-lived than their spring equivalents. Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-deplete surface water. ...


In the open ocean, the condition that typically causes diatom (spring) blooms to end is a lack of silicon. Unlike other nutrients, this is only a major requirement of diatoms so it is not regenerated in the plankton ecosystem as efficiently as, for instance, nitrogen or phosphorus nutrients. This can be seen in maps of surface nutrient concentrations - as nutrients decline along gradients, silicon is usually the first to be exhausted (followed normally by nitrogen then phosphorus). General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... General Name, Symbol, Number phosphorus, P, 15 Chemical series nonmetals Group, Period, Block 15, 3, p Appearance waxy white/ red/ black/ colorless Standard atomic weight 30. ...


Because of this bloom-and-bust lifestyle, diatoms are believed to play a disproportionately important role in the export of carbon from oceanic surface waters[7][6] (see also the biological pump). Significantly, they also play a key role in the regulation of the biogeochemical cycle of silicon in the modern ocean[4][8]. In oceanic biogeochemistry, the biological pump is the sum of a suite of biologically-mediated processes that transport carbon from the surface euphotic zone to the oceans interior. ... It has been suggested that Silicons ranking be merged into this article or section. ...

Egge & Aksnes (1992)[9] figure

The use of silicon by diatoms is believed by many researchers to be the key to their ecological success. In a now classic study, Egge & Aksnes (1992)[9] found that diatom dominance of mesocosm communities was directly related to the availability of silicate. When silicon content approaches a concentration of 2 mmol m-3, diatoms typically represent more than 70% of the phytoplankton community. Raven (1983)[10] noted that, relative to organic cell walls, silica frustules require less energy to synthesize (approximately 8%), potentially a significant saving on the overall cell energy budget. Other researchers[11] have suggested that the biogenic silica in diatom cell walls acts as an effective pH buffering agent, facilitating the conversion of bicarbonate to dissolved CO2 (which is more readily assimilated). Notwithstanding the possible advantages conferred by silicon, diatoms typically have higher growth rates than other algae of a corresponding size[5]. Image File history File links Download high resolution version (994x615, 21 KB)Diatom fraction of algal population as a function of ambient silicic acid. ... Image File history File links Download high resolution version (994x615, 21 KB)Diatom fraction of algal population as a function of ambient silicic acid. ... Milli (symbol m) is an SI prefix in the SI system of units denoting a factor of 10-3, or 1/1,000. ... The mole (symbol: mol) is the SI base unit that measures an amount of substance. ... The metre (or meter, see spelling differences) is a measure of length. ... The correct title of this article is . ... A buffering agent adjusts the pH of a solution. ... In inorganic chemistry, a bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. ...


Evolutionary history

Heterokont chloroplasts appear to be derived from those of red algae, rather than directly from prokaryotes as occurs in plants. This suggests they had a more recent origin than many other algae. However, fossil evidence is scant, and it is really only with the evolution of the diatoms themselves that the heterokonts make a serious impression on the fossil record. Possible classes Florideophyceae Bangiophyceae Cyanidiophyceae Red algae (Rhodophyta, pronounced /ˈrəʊdə(ʊ)ˌfʌɪtə/) are a large group of mostly multicellular, marine algae, including many notable seaweeds. ... Prokaryotes (pro-KAR-ee-oht) (from Old Greek pro- before + karyon nut or kernel, referring to the cell nucleus, + suffix -otos, pl. ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta—liverworts Anthocerotophyta—hornworts Bryophyta—mosses Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta—ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta—seed ferns Pinophyta—conifers Cycadophyta—cycads Ginkgophyta—ginkgo Gnetophyta—gnetae Magnoliophyta—flowering plants...


The earliest known fossil diatoms date from the early Jurassic (~185 Ma)[12], although recent molecular clock[12] and sedimentary[13] evidence suggests an earlier origin. It has been suggested that their origin may be related to the end-Permian mass extinction (~250 Ma), after which many marine niches were opened[14]. The gap between this event and the time that fossil diatoms first appear may indicate a period when diatoms were unsilicified and their evolution was cryptic[15]. Since the advent of silicification, diatoms have made a significant impression on the fossil record, with major deposits of fossil diatoms found as far back as the early Cretaceous, and some rocks (diatomaceous earth, diatomite, kieselguhr) being composed almost entirely of them. Mega-annum, usually abbreviated as Ma, is a unit of time equal to one million years. ... The molecular clock (based on the molecular clock hypothesis (MCH)) is a technique in genetics, which researchers use to date when two species diverged. ... This article does not cite its references or sources. ... The Permian is a geologic period that extends from about 299. ... An extinction event (also extinction-level event, ELE) is a period in time when a large number of species die out. ... Two lichenes species on a rock, in two different ecological niches In ecology, a niche is a term describing the relational position of a species or population in an ecosystem. ... (this page is about animals that hide or use camouflage. ... The Cretaceous Period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic Period (i. ... A sample of diatomaceous earth Diatomaceous earth (IPA: , also known as DE, diatomite, diahydro, kieselguhr, kieselgur and Celite) is a naturally occurring, soft, chalk-like sedimentary rock that is easily crumbled into a fine white to off-white powder. ...


Although the diatoms may have existed since the Triassic, the timing of their ascendancy and "take-over" of the silicon cycle is more recent. Prior to the Phanerozoic (before 544 Ma), it is believed that microbial or inorganic processes weakly regulated the ocean's silicon cycle[16][17][18]. Subsequently, the cycle appears dominated (and more strongly regulated) by the radiolarians and siliceous sponges, the former as zooplankton, the latter as sedentary filter feeders primarily on the continental shelves[19]. Within the last 100 My, it is thought that the silicon cycle has come under even tighter control, and that this derives from the ecological ascendancy of the diatoms. The Triassic is a geologic period that extends from about 251 ± 0. ... The Phanerozoic (occasionally Phaenerozoic) Eon is the period of geologic time during which abundant animal life has existed. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Inorganic chemistry is the branch of chemistry concerned with the properties and reactions of inorganic compounds. ... Possible classes Polycystinea Acantharea Taxopodea 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. ... Classes Calcarea Hexactinellida Demospongiae The sponges or poriferans (from Latin porus pore and ferre to bear) are animals of the phylum Porifera. ... Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. ... The term sedentary in biology and anthropology applies to organisms and species that are not migratory but rather remain at a single location (permanently fixed or otherwise). ... Filter feeders (also known as suspension feeders) are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized structure, such as the baleen of baleen whales. ...  Sediment  Rock  Mantle  The global continental shelf, highlighted in cyan The continental shelf is the extended perimeter of each continent, which is covered during interglacial periods such as the current epoch by relatively shallow seas (known as shelf seas) and gulfs. ...


However, the precise timing of the "take-over" is unclear, and different authors have conflicting interpretations of the fossil record. Some evidence, such as the eviction of siliceous sponges from the shelves[20], suggests that this takeover began in the Cretaceous (146 Ma to 65 Ma), while evidence from radiolarians suggests "take-over" did not begin until the Cenozoic (65 Ma to present)[21]. Nevertheless, regardless of the details of the "take-over" timing, it is clear that this most recent revolution has installed much tighter biological control over the biogeochemical cycle of silicon. To meet Wikipedias quality standards, this article or section may require cleanup. ... The Cenozoic Era (IPA pronunciation: ); sometimes Caenozoic Era (in the United Kingdom), meaning new life (Greek (kainos), new, and (zoe), life), is the most recent of the three classic geological eras. ... The storming of the Bastille, 14 July 1789 during the French Revolution. ... In ecology, a biogeochemical cycle is a circuit where a nutrient moves back and forth between both biotic and abiotic components of ecosystems. ...


Collection

Living diatoms are often found clinging in great numbers to filamentous algae, or forming gelatinous masses on various submerged plants. Cladophora is frequently covered with Cocconeis, an elliptically shaped diatom; Vaucheria is often covered with small forms. Diatoms frequently present as a brown, slippery coating on submerged stones and sticks, and may be seen to "stream" with river current. Marimo (Japanese: 毬藻 marimo), also known as Cladophora ball in English, are a variety of algae found in some lakes of Japan, Iceland and Estonia. ...


The surface mud of a pond, ditch, or lagoon will almost always yield some diatoms. They can be made to emerge by filling a jar with water and mud, wrapping it in black black paper and letting direct sunlight fall on the surface of the water. Within a day, the diatoms will come to the top in a scum and can be isolated.


Since diatoms form an important part of the food of molluscs, tunicates, and fishes, the alimentary tracts of these animals often yield forms that are not easily secured in other ways. Marine diatoms can be collected by direct water sampling, though benthic forms can be secured by scraping barnacles, oyster shells, and other shells. Classes Caudofoveata Aplacophora Polyplacophora - Chitons Monoplacophora Bivalvia - Bivalves Scaphopoda - Tusk shells Gastropoda - Snails and Slugs Cephalopoda - Squids, Octopuses, etc. ... Classes Ascidiacea Thaliacea Appendicularia Sorberacea Urochordata (sometimes known as tunicata and commonly called urochordates, tunicates, sea squirts or cunji) is the subphylum of saclike filter feeders with incurrent and excurrent siphons. ... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... For the Physics term GUT, please refer to Grand unification theory The gastrointestinal or digestive tract, also referred to as the GI tract or the alimentary canal or the gut, is the system of organs within multicellular animals which takes in food, digests it to extract energy and nutrients, and... Superorders Acrothoracica Thoracica Rhizocephala A barnacle is a type of arthropod belonging to infraclass Cirripedia in the subphylum Crustacea and is hence distantly related to crabs and lobsters. ... Crassostrea gigas, Marennes-Oléron Crassostrea gigas, Marennes-Oléron Crassostrea gigas, Marennes-Oléron, opened The name oyster is used for a number of different groups of mollusks which grow for the most part in marine or brackish water. ...


The silicious shells of diatoms are among the most beautiful objects which can be examined with the microscope. To obtain perfectly clean mounts requires considerable time and patience, but once the material is cleaned, preparations may be made at any time with very little trouble. Robert Hookes microscope (1665) - an engineered device used to study living systems. ...


This section uses text from Methods in Plant Histology[22].


Genome sequencing

The entire genome of the centric diatom, Thalassiosira pseudonana, has been sequenced[23], and the sequencing of a second diatom genome from the pennate diatom Phaeodactylum tricornutum is in progress. The first insights into the genome properties of the P. tricornutum gene repertoire was described using 1,000 ESTs[24]. Subsequently, the number of ESTs was extended to 12,000 and the Diatom EST Database was constructed for functional analyses[25]. These sequences have been used to make a comparative analysis between P. tricornutum and the putative complete proteomes from the green alga Chlamydomonas reinhardtii, the red alga Cyanidioschyzon merolae, and the centric diatom T. pseudonana[26]. In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... Thalassiosira pseudonana is a species of marine centric diatom. ... In genetics and biochemistry, sequencing means to determine the primary structure (or primary sequence) of an unbranched biopolymer. ... There are very few or no other articles that link to this one. ... An expressed sequence tag or EST is a short sub-sequence of a transcribed spliced nucleotide sequence (either protein-coding or not). ... Divisions Chlorophyta Charophyta Green algae are microscopic protists; found in all aquatic environments, including marine, freshwater and brackish water. ... Binomial name Chlamydomonas reinhardtii P.A.Dang. ... Possible classes Florideophyceae Bangiophyceae Cyanidiophyceae The red algae (Rhodophyta, IPA: , from Greek: (rhodon) = rose + (phyton) = plant, thus red plant) are a large group, about 5000 - 6000 species [1] of mostly multicellular, marine algae, including many notable seaweeds. ...


References

  1. ^ a b c Round, F. E. and Crawford, R. M. (1990). The Diatoms. Biology and Morphology of the Genera, Cambridge University Press, UK.
  2. ^ Mann, D. G. (1999). The species concept in diatoms. Phycologia 38, 437-495.
  3. ^ Hoek, C. van den, Mann, D. G. and Jahns, H. M. (1995). Algae : An introduction to phycology, Cambridge University Press, UK.
  4. ^ a b Treguer, P., Nelson, D. M., Van Bennekom, A. J., DeMaster, D. J., Leynaert, A. and Queguiner, B. (1995). The silica balance in the world ocean : A reestimate. Science 268, 375-379.
  5. ^ a b Furnas, M. J. (1990). In situ growth rates of marine phytoplankton : Approaches to measurement, community and species growth rates. J. Plankton Res. 12, 1117-1151.
  6. ^ a b Dugdale, R. C. and Wilkerson, F. P. (1998). Silicate regulation of new production in the equatorial Pacific upwelling. Nature 391, 270-273.
  7. ^ Smetacek, V. S. (1985). Role of sinking in diatom life-history cycles : Ecological, evolutionary and geological significance. Mar. Biol. 84, 239-251.
  8. ^ Yool, A. and Tyrrell, T. (2003). Role of diatoms in regulating the ocean's silicon cycle. Global Biogeochemical Cycles 17, 1103, doi:10.1029/2002GB002018.
  9. ^ a b Egge, J. K. and Aksnes, D. L. (1992). Silicate as regulating nutrient in phytoplankton competition. Mar. Ecol. Prog. Ser. 83, 281-289.
  10. ^ Raven, J. A. (1983). The transport and function of silicon in plants. Biol. Rev. 58, 179-207.
  11. ^ Milligan, A. J. and Morel, F. M. M. (2002). A proton buffering role for silica in diatoms. Science 297, 1848-1850.
  12. ^ a b Kooistra, W. H. C. F. and Medlin, L. K. (1996). Evolution of the diatoms (Bacillariophyta) : IV. A reconstruction of their age from small subunit rRNA coding regions and the fossil record. Mol. Phylogenet. Evol. 6, 391-407.
  13. ^ Schieber, J., Krinsley, D. and Riciputi, L. (2000). Diagenetic origin of quartz silt in mudstones and implications for silica cycling. Nature 406, 981-985.
  14. ^ Medlin, L. K., Kooistra, W. H. C. F., Gersonde, R., Sims, P. A. and Wellbrock, U. (1997). Is the origin of the diatoms related to the end-Permian mass extinction? Nova Hedwegia 65, 1-11.
  15. ^ Raven, J. A. and Waite, A. M. (2004). The evolution of silicification in diatoms : inescapable sinking and sinking as escape? New Phytologist 162, 45-61.
  16. ^ Siever, R. (1991). Silica in the oceans : biological-geological interplay. In : Schneider, S. H., Boston, P. H. (eds.), Scientists On Gaia, The MIT Press, Cambridge MA, USA, pp. 287-295.
  17. ^ Kidder, D. L. and Erwin, D. H. (2001). Secular distribution of biogenic silica through the Phanerozoic : Comparison of silica-replaced fossils and bedded cherts at the series level. J. Geol. 109, 509-522.
  18. ^ Grenne, T. and Slack, J. F. (2003). Paleozoic and Mesozoic silic-rich seawater : evidence from hematitic chert (jasper) deposits. Geology 31, 319-322.
  19. ^ Racki, G. and Cordey, F. (2000). Radiolarian palaeoecology and radiolarites : is the present the key to the past? Earth-Science Reviews 52, 83-120.
  20. ^ Maldonado, M., Carmona, M. C., Uriz, J. M. and Cruzado, A. (1999). Decline in Mesozoic reef-building sponges explained by silicate limitation. Nature 401, 785-788.
  21. ^ Harper, H. E. and Knoll, A. H. (1975). Silica, diatoms, and Cenozoic radiolarian evolution. Geology 3, 175-177.
  22. ^ Chamberlain, C. J. (1901) Methods in Plant Histology, University of Chicago Press, USA.
  23. ^ Armbrust et al. (2004). The genome of the diatom Thalassiosira pseudonana: ecology, evolution, and metabolism. Science 306, 79-86.
  24. ^ Scala, S., Carels, N., Falciatore, A., Chiusano, M.L. and Bowler, C. (2002). Genome properties of the diatom Phaeodactylum tricornutum. Plant Physiology 129, 993-1002.
  25. ^ Maheswari, U., Montsant, A., Goll, J., Krishnasamy, S., Rajyashri, K.R., Patell, V.M. and Bowler, C. (2005). The Diatom EST Database. Nucleic Acids Research 33, 344–347.
  26. ^ Montsant, A., Jabbari, K., Maheswari, U. and Bowler, C. (2005). Comparative Genomics of the Pennate Diatom Phaeodactylum tricornutum. Plant Physiology 137, 500-513.

See also

A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ... In oceanic biogeochemistry, the biological pump is the sum of a suite of biologically-mediated processes that transport carbon from the surface euphotic zone to the oceans interior. ... A sample of diatomaceous earth Diatomaceous earth (IPA: , also known as DE, diatomite, diahydro, kieselguhr, kieselgur and Celite) is a naturally occurring, soft, chalk-like sedimentary rock that is easily crumbled into a fine white to off-white powder. ... Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of the plankton that drift in the water column. ... Photomontage of plankton organisms Plankton are any drifting organism that inhabits the water column of oceans, seas, and bodies of fresh water. ...

External links

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Diatoms

  Results from FactBites:
 
Diatom (552 words)
Most diatoms are single cells and live between two silicate shells, one overlapping the other like the two halves of a petri dish.
The diatoms are divided into two main groups: the pennate diatoms, which are bilaterally symmetrical, and the centrate diatoms, which are radially symmetric.
Since diatoms form an important part of the food of molluscs, tunicates, and fishes, the alimentary tracts of these animals often yield deep-water forms which are not easily secured in any other way.
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