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Acantharian
The Acantharea (Acantharia) are a group of radiolarian protozoa, distinguished mainly by their strontium sulfate skeletons. Acantharians are heterotrophic marine microplankton that range in size from about 200 microns in diameter up to several millimeters. Some acantharians have photosynthetic endosymbionts and hence are considered mixotrophs. Morphology Acantharian skeletons are composed of strontium sulfate, SrSO4, in the form of mineral celestine crystal. Celestine is named for the delicate blue colour of its crystals, and is the heaviest mineral in the ocean. The denseness of their celestite ensures acantharian shells function as mineral ballast, resulting in fast sedimentation to bathypelagic depths. High settling fluxes of acantharian cysts have been observed at times in the Iceland Basin and the Southern Ocean, as much as half of the total gravitational organic carbon flux. Material was copied from this source, which is available under Creative Commons Attribution 4 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phaeocystis
''Phaeocystis'' is a genus of algae belonging to the Prymnesiophyte class and to the larger division of Haptophyta. It is a widespread marine phytoplankton and can function at a wide range of temperatures (eurythermal) and salinities (euryhaline). Members of this genus live in the open ocean, as well as in sea ice. It has a polymorphic life cycle, ranging from free-living cells to large colonies. The ability to form a floating colony is one of the unique attributes of ''Phaeocystis'' – hundreds of cells are embedded in a polysaccharide gel matrix, which can increase massively in size during blooms. The largest ''Phaeocystis'' blooms form in the polar seas: ''P. pouchetii'' in the north and ''P. antarctica'' in the south. This intense ''Phaeocystis'' productivity generally persists for about a three-month period, spanning most of the summer in the Southern Hemisphere. ''Phaeocystis''-abundant ecosystems are generally associated with commercially important stocks of crustac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mixotroph
A mixotroph is an organism that can use a mix of different sources of energy and carbon, instead of having a single trophic mode on the continuum from complete autotrophy at one end to heterotrophy at the other. It is estimated that mixotrophs comprise more than half of all microscopic plankton. There are two types of eukaryotic mixotrophs: those with their own chloroplasts, and those with endosymbionts—and those that acquire them through kleptoplasty or by enslaving the entire phototrophic cell. Possible combinations are photo- and chemotrophy, litho- and organotrophy (osmotrophy, phagotrophy and myzocytosis), auto- and heterotrophy or other combinations of these. Mixotrophs can be either eukaryotic or prokaryotic. They can take advantage of different environmental conditions. If a trophic mode is obligate, then it is always necessary for sustaining growth and maintenance; if facultative, it can be used as a supplemental source. Some organisms have incomplete Calvin cycles, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiolaria
The Radiolaria, also called Radiozoa, are protozoa of diameter 0.1–0.2 mm that produce intricate mineral skeletons, typically with a central capsule dividing the cell (biology), cell into the inner and outer portions of endoplasm and Ectoplasm (cell biology), ectoplasm. The elaborate mineral skeleton is usually made of Silicon dioxide, silica. They are found as zooplankton throughout the global ocean. As zooplankton, radiolarians are primarily heterotrophic, but many have photosynthetic endosymbionts and are, therefore, considered mixotrophs. The skeletal remains of some types of radiolarians make up a large part of the cover of the ocean floor as siliceous ooze. Due to their rapid change as species and intricate skeletons, radiolarians represent an important diagnostic fossil found from the Cambrian onwards. Description Radiolarians have many needle-like pseudopods supported by bundles of microtubules, which aid in the radiolarian's buoyancy. The cell nucleus and most oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microfibril
A microfibril is a very fine fibril, or fiber-like strand, consisting of glycoproteins and cellulose. It is usually, but not always, used as a general term in describing the structure of protein fiber, e.g. hair and sperm tail. Its most frequently observed structural pattern is the 9+2 pattern in which two central protofibrils are surrounded by nine other pairs. Cellulose inside plants is one of the examples of non-protein compounds that are using this term with the same purpose. Cellulose microfibrils are laid down in the inner surface of the primary cell wall. As the cell absorbs water, its volume increases and the existing microfibrils separate and new ones are formed to help increase cell strength. Synthesis and function Cellulose is synthesized by cellulose synthase or Rosette terminal complexes which reside on a cells membrane. As cellulose fibrils are synthesized and grow extracellularly they push up against neighboring cells. Since the neighboring cell can not move easily t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chrysochromulina
''Chrysochromulina'' is a genus of haptophytes. This phytoplankton is distributed globally in brackish and marine waters across approximately 60 known species. All ''Chrysochromulina'' species are phototrophic, however some have been shown to be mixotrophic, including exhibiting phagotrophy under certain environmental conditions. The cells are small, characterized by having scales, and typically observed using electron microscopy. Some species, under certain environmental conditions have been shown to produce toxic compounds that are harmful to larger marine life including fish. Morphology Individuals of the genus are known to grow between 3.0 and 13.0 µm in length, with the largest being those of the ''Chrysochromulina polylepis'' species. The cell surface is covered with plate-like scales, with additional layers of different scale types often overlaid. As is characteristic of all haptophytes, members of the genus ''Chrysochromulina'' possess two flagella and a unique ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haptophyte
The haptophytes, classified either as the Haptophyta, Haptophytina or Prymnesiophyta (named for ''Prymnesium''), are a clade of algae. The names Haptophyceae or Prymnesiophyceae are sometimes used instead. This ending implies classification at the class rank rather than as a division. Although the phylogenetics of this group has become much better understood in recent years, there remains some dispute over which rank is most appropriate. Characteristics The chloroplasts are pigmented similarly to those of the heterokonts, but the structure of the rest of the cell is different, so it may be that they are a separate line whose chloroplasts are derived from similar red algal endosymbionts. The cells typically have two slightly unequal flagella, both of which are smooth, and a unique organelle called a ''haptonema'', which is superficially similar to a flagellum but differs in the arrangement of microtubules and in its use. The name comes from the Greek ''hapsis'', touch, and ''n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pelagodinium Béii
''Pelagodinium béii'' is a photosynthetic dinoflagellate that forms a symbiotic relationship with planktonic foraminifera. Discovery and classification ''P. béii'' was originally described as ''Gymnodinium béii'' by marine isotope geochemist Howard Spero in 1987, after being discovered in the eastern Pacific Ocean. It was redefined as ''P. béii'' in 2010 after its Ribosomal RNA was characterized, revealing it to be a relative of the genus ''Symbiodinium''. ''Symbiodinium'' is a well-studied endosymbiont of deep water invertebrates, protists and foraminifera, found especially alongside reef-dwelling organisms. Ecology The ''P. béii'' contains a single straight elongated apical vesicle with a row of small knobs, eight latitudinal series of amphiesmal vesicles, and a Type E eyespot. When not living as a symbiont the species is able to enter a motile stage. Like ''Symbiodinium'', ''P. béii'' is a member of the Suessiales order, which lack thecal armored plates. ''P. béii'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinoflagellate
The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are mostly marine plankton, but they also are common in freshwater habitats. Their populations vary with sea surface temperature, salinity, and depth. Many dinoflagellates are photosynthetic, but a large fraction of these are in fact mixotrophic, combining photosynthesis with ingestion of prey (phagotrophy and myzocytosis). In terms of number of species, dinoflagellates are one of the largest groups of marine eukaryotes, although substantially smaller than diatoms. Some species are endosymbionts of marine animals and play an important part in the biology of coral reefs. Other dinoflagellates are unpigmented predators on other protozoa, and a few forms are parasitic (for example, ''Oodinium'' and ''Pfiesteria''). Some dinoflagellates pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acantharia Confocial Micrograph 2
''Acantharia'' is a genus of fungi in the Venturiaceae family. Species * ''Acantharia aterrima'' (Cooke & G. Winter) Arx (1954) * ''Acantharia chaetomoides'' W.H. Hsieh, Chi Y. Chen & Sivan. (1995) * ''Acantharia echinata'' (Ellis & Everh.) Theiss. & Syd. (1918) * ''Acantharia elegans'' (Syd. & P. Syd.) Arx (1954) * ''Acantharia hamata'' (Penz. & Sacc.) Arx (1954) * ''Acantharia quercus-dilatatae'' S.K. Bose & E. Müll. (1965) * ''Acantharia sinensis'' (Petr.) Arx (1954) References Index Fungorum species listing External links *Acantharia' at Index Fungorum ''Index Fungorum'' is an international project to index all formal names ( scientific names) in the fungus kingdom. the project is based at the Royal Botanic Gardens, Kew, one of three partners along with Landcare Research and the Institute of M ... Venturiaceae Taxa named by Hans Sydow {{Pleosporales stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribosomal RNA
Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosomal DNA (rDNA) and then bound to ribosomal proteins to form SSU rRNA, small and LSU rRNA, large ribosome subunits. rRNA is the physical and mechanical factor of the ribosome that forces transfer RNA (tRNA) and messenger RNA (mRNA) to process and Translation (biology), translate the latter into proteins. Ribosomal RNA is the predominant form of RNA found in most cells; it makes up about 80% of cellular RNA despite never being translated into proteins itself. Ribosomes are composed of approximately 60% rRNA and 40% ribosomal proteins by mass. Structure Although the primary structure of rRNA sequences can vary across organisms, Base pair, base-pairing within these sequences commonly forms stem-loop configurations. The length and position of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylogenetic Tree
A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical or genetic characteristics. All life on Earth is part of a single phylogenetic tree, indicating common ancestry. In a ''rooted'' phylogenetic tree, each node with descendants represents the inferred most recent common ancestor of those descendants, and the edge lengths in some trees may be interpreted as time estimates. Each node is called a taxonomic unit. Internal nodes are generally called hypothetical taxonomic units, as they cannot be directly observed. Trees are useful in fields of biology such as bioinformatics, systematics, and phylogenetics. ''Unrooted'' trees illustrate only the relatedness of the leaf nodes and do not require the ancestral root to b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthracanthida
Radiolaria (Challenger) Plate. Arthracanthida, a subclass of Acantharea, is a group of marine protozoans. They consist mainly of a gelatinous sheath filled with cytoplasm and a skeleton of up to 20 radially placed spicules made of celestine (strontium sulfate). While mostly found in the upper areas of the ocean, they are able to move vertically by using microfilaments attached to the spicules to expand and contract the sheath. They are plentiful in the Gulf Stream The Gulf Stream, together with its northern extension the North Atlantic Current, North Atlantic Drift, is a warm and swift Atlantic Ocean, Atlantic ocean current that originates in the Gulf of Mexico and flows through the Straits of Florida a ... during the summer months, but little is known about their overall distribution. References *L. H. Hyman, The Invertebrates, vol. 1, McGraw-Hill, 1940 *T. Cavalier-Smith, Kingdom Protozoa and its 18 phyla, Microbiol. Rev., 57(4):953–994, 1993 *K. Hausmann and N. Hulsma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
