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Centrohelid
The centrohelids or centroheliozoa are a large group of heliozoan protists. They include both mobile and sessile forms, found in freshwater and marine environments, especially at some depth. Characteristics Individuals are unicellular and spherical, usually around 30–80 μm in diameter, and covered with long radial axopods, narrow cellular projections that capture food and allow mobile forms to move about. A few genera have no cell covering, but most have a gelatinous coat holding scales and spines, produced in special deposition vesicles. These may be organic or siliceous and come in various shapes and sizes. For instance, in '' Raphidiophrys'' the coat extends along the bases of the axopods, covering them with curved spicules that give them a pine-treeish look, and in ''Raphidiocystis'' there are both short cup-shaped spicules and long tubular spicules that are only a little shorter than the axopods. Some other common genera include '' Heterophrys'', ''Actinocystis'', and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yogsothoth (protist)
''Yogsothoth'' is a genus of centrohelid protists, distinguished by the shape and arrangement of their external scales as well as their colonial life strategy. It was described in November 2018 by Shɨshkin and Zlatogursky, and is part of a newly described clade of centrohelids, determined as such by analysis of molecular data. Etymology The genus name ''Yogsothoth'' is a reference to Yog-Sothoth, a character from H.P. Lovecraft's creative works. The genus was named as such due to its tendency to form colonies of cells with rounded plate-like outer scales and outwardly-radiating axopodia, which is visually similar to Lovecraft's description of Yog-sothoth as a conglomeration of glowing spheres. History of knowledge ''Yogsothoth'' was first described by Shɨshkin and Zlatogursky in November 2018, and was placed within the taxon Panacanthocystidia after identifying that it had too few 18S insertions to be classified under the established taxon of Acanthocystidia. Proposed t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raphidiophrys
Raphidiophrys is a genus of centrohelid The centrohelids or centroheliozoa are a large group of heliozoan protists. They include both mobile and sessile forms, found in freshwater and marine environments, especially at some depth. Characteristics Individuals are unicellular and spher ... with radiating axopodia.Zlatogursky, V. V. (2012). ''Raphidiophrys heterophryoidea'' sp. nov. (Centrohelida: Raphidiophryidae), the first heliozoan species with a combination of siliceous and organic skeletal elements. ''European Journal of Protistology, 48''(1), 9-16. doi:10.1016/j.ejop.2011.09.004 ''R. intermedia'' is found in the bottom sludge of freshwater bodies in Canada, Chile, Argentina, Australia, New Zealand, Malaysia, Russia, and central Europe. ''Raphidiophrys'' have bipartite scales are a defining characteristic among species. Differences in type and size of scales are used to differentiate amongst the members of this genus. The genus ''Raphidiophrys'' was discovered in 1867 by W. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protist
A protist ( ) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a paraphyletic grouping of all descendants of the last eukaryotic common ancestor excluding land plants, animals, and fungi. Protists were historically regarded as a separate taxonomic kingdom known as Protista or Protoctista. With the advent of phylogenetic analysis and electron microscopy studies, the use of Protista as a formal taxon was gradually abandoned. In modern classifications, protists are spread across several eukaryotic clades called supergroups, such as Archaeplastida ( photoautotrophs that includes land plants), SAR, Obazoa (which includes fungi and animals), Amoebozoa and " Excavata". Protists represent an extremely large genetic and ecological diversity in all environments, including extreme habitats. Their diversity, larger than for all other eukaryotes, has only been discovered in rece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raphidiophrys Contractilis
''Raphidiophrys contractilis'' is a species of freshwater centrohelid. Discovery This species was first isolated from a brackish pond in Shukkeien Garden, Naka-ku, Hiroshima City, Japan. Description ''Raphidiophrys contractilis'' is a spherical organism measuring between 7 and 19 μm in diameter and has several axopodia measuring between 60 and 110 μm. The axopodia are sustained by a set of microtubules arranged in a complex of hexagons and triangles. The cell body is coated by a thin layer of small scales composed of silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f .... These scales are oblong, with curved edges and with the surface always facing the cell body. Feeding behavior ''Raphidiophrys contractilis'' preys on other protists, such as flagellates and ciliat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hacrobia
The cryptomonads-haptophytes assemblage is a proposed but disputed monophyletic grouping of unicellular eukaryotes that are not included in the SAR supergroup. Several alternative names have been used for the group, including Hacrobia (derived from "ha-" referring to Haptophyta, "-cr-" referring to cryptomonads, and "-bia" as a general suffix referring to life); CCTH (standing for Cryptophyta, Centrohelida, Telonemia and Haptophyta); and "Eukaryomonadae". , it is unclear whether this group is monophyletic or not; results of phylogenetic studies are "often dependent on the selection of taxa and gene data set". Two 2012 studies produced opposite results. Members In the past, heterokonts, haptophytes, and cryptomonads have sometimes been grouped together in a group known as chromists. Though the heterokonts are now split out, Cryptophyta and Haptophyta are considered in some studies to be closely related (and are sometimes simply referred to as the "Cryptophyta+Haptophyta" g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhizaria
The Rhizaria are a diverse and species-rich clade of mostly unicellular eukaryotes. Except for the Chlorarachniophytes and three species in the genus '' Paulinella'' in the phylum Cercozoa, they are all non-photosynthetic, but many Foraminifera and Radiolaria have a symbiotic relationship with unicellular algae. A multicellular form, ''Guttulinopsis vulgaris'', a cellular slime mold, has been described. This group was used by Cavalier-Smith in 2002, although the term "Rhizaria" had been long used for clades within the currently recognized taxon. Being described mainly from rDNA sequences, they vary considerably in form, having no clear morphological distinctive characters ( synapomorphies), but for the most part they are amoeboids with filose, reticulose, or microtubule-supported pseudopods. In the absence of an apomorphy, the group is ill-defined, and its composition has been very fluid. Some Rhizaria possess mineral exoskeletons ( thecae or loricas), which are in diffe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gymnosphaerid
The gymnosphaerids (or Gymnosphaerida) are a small group of heliozoan protists found in marine environments. They tend to be roughly spherical with radially directed axopods, supported by microtubules in a triangular-hexagonal array arising from an amorphous central granule. Genera There are only three genera, each with a single species: ''Gymnosphaera albida'', ''Hedraiophrys hovassei'', and ''Actinocoryne contractilis''. *''Gymnosphaera albida'' is free-living, usually benthic in shallow water. The cells are round and naked, around 70-100 μm in diameter, and resemble the unrelated '' Actinosphaerium''. The outer cytoplasm, or ectoplasm, forms a distinct layer containing large vesicles. *''Hedraiophrys hovassei'' is larger and lives attached to algae and other objects. The cells have a conical base, and are covered with long siliceous spicules. The ectoplasm is distinct and frothy, and typically contains bacterial and algal endosymbionts. *''Actinocoryne contractilis'' is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxnerella
''Oxnerella'' is a genus of centrohelid The centrohelids or centroheliozoa are a large group of heliozoan protists. They include both mobile and sessile forms, found in freshwater and marine environments, especially at some depth. Characteristics Individuals are unicellular and spher .... It includes the species ''Oxnerella maritima''. References {{Taxonbar, from=Q2912108 Haptista genera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raphidiophryidae
Raphidiophryidae is a family of mostly freshwater centrohelids. It is the sister family of Acanthocystidae, sharing the trait of presenting silica scales and comprising the clade Chalarothoracina. Two genera, ''Raphidiophrys Raphidiophrys is a genus of centrohelid The centrohelids or centroheliozoa are a large group of heliozoan protists. They include both mobile and sessile forms, found in freshwater and marine environments, especially at some depth. Characteris ...'' and '' Polyplacocystis'', have been discovered so far. References {{Taxonbar, from=Q16989009 Haptista Haptista families ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
