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Heliozoan
Heliozoa, commonly known as sun-animalcules, are microbial eukaryotes (protists) with stiff arms ( axopodia) radiating from their spherical bodies, which are responsible for their common name. The axopodia are microtubule-supported projections from the amoeboid cell body, and are variously used for capturing food, sensation, movement, and attachment. They are similar to Radiolaria, but they are distinguished from them by lacking central capsules and other complex skeletal elements, although some produce simple scales and spines. They may be found in both freshwater and marine environments. Classification Originally the heliozoa were treated together as a formal taxon Heliozoa or Heliozoea, with the rank of class or phylum, but it has been realised that they are polyphyletic, as the various orders show notable differences and are no longer believed to be descended from a single common ancestor. Instead, "heliozoa" is regarded as a descriptive term applying to various lines of proti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinophryida
The actinophryids are an order of heliozoa, a polyphyletic array of stramenopiles, having a close relationship with pedinellids and ''Ciliophrys''. They are common in fresh water and occasionally found in marine and soil habitats. Actinophryids are unicellular and roughly spherical in shape, with many axopodia that radiate outward from the cell body. Axopodia are a type of pseudopodia that are supported by hundreds of microtubules arranged in interlocking spirals and forming a needle-like internal structure or axoneme. Small granules, extrusomes, that lie under the membrane of the body and axopodia capture flagellates, ciliates and small metazoa that make contact with the arms. Description Actinophryids are largely aquatic protozoa with a spherical cell body and many needle-like axopodia. They resemble the shape of a sun due to this structure, which is the inspiration for their common name: heliozoa, or "sun-animalcules". Their bodies, without arms, range in size from a few tens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pedinellid
Pedinellales is a group of single-celled algae found in both marine environments and freshwater. These are found in both freshwater and marine environments, and most genera are sessile, attached by posterior stalks. The flagellum is at the anterior of the cell, and the tentacles surround it, often capturing small prey drawn in by its current. The colored genera are ''Pedinella'', '' Apedinella'', '' Pseudopedinella'', and '' Mesopedinella''. Several more genera have lost their chloroplasts and feed entirely by phagocytosis. These are ''Parapedinella'', '' Actinomonas'', and '' Pteridomonas''. It also appears that certain heliozoa are actually derived pedinellids. ''Ciliophrys'' alternates between a mobile flagellate stage and a heliozoan feeding stage, where the body is contracted with extended axopods all over its surface, and the flagellum is curled up into a tight figure eight. The actinophryids, ''Actinophrys'' and ''Actinosphaerium'', exist only in a heliozoan form wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protists
A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exclusion of other eukaryotes means that protists do not form a natural group, or clade. Therefore, some protists may be more closely related to animals, plants, or fungi than they are to other protists. However, like the groups ''algae'', ''invertebrates'', and ''protozoans'', the biological category ''protist'' is used for convenience. Others classify any unicellular eukaryotic microorganism as a protist. The study of protists is termed protistology. History The classification of a third kingdom separate from animals and plants was first proposed by John Hogg in 1860 as the kingdom Protoctista; in 1866 Ernst Haeckel also proposed a third kingdom Protista as "the kingdom of primitive forms". Originally these also included prokaryotes, but ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Louis Joblot
Louis Joblot (9 August 1645 – 27 April 1723) was a French naturalist. He was born in Bar-le-Duc and died, aged 57, in Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S .... Publications * Louis Joblot, ''Descriptions et usages de plusiers nouveaux microscopes tant simples que composez ; avec de nouvelles observations faites sur de multitude innombrable d'insectes, & d'autres animaux de diverses especes, qui naissent dans des liqueurs préparées, & dans celles qui ne le sont point'', J. Collombat, printer, Paris, 1718. Sources * Hubert Lechevalier, "Louis Joblot and His Microscopes", ''Bacteriological Reviews'', Vol.40, No.1, March 1976, p. 241-258PDF* P.W. van der Pas ''Complete Dictionary of Scientific Biography'', 2008. References External links ''Observer au ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hacrobia
The cryptomonads-haptophytes assemblage is a proposed 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" group). A 2009 pape ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleariid
Nucleariida is a group of amoebae with filose pseudopods, known mostly from soils and freshwater. They are distinguished from the superficially similar vampyrellids mainly by having mitochondria with discoid cristae, in the absence of superficial granules, and in the way they consume food. Classification Molecular studies indicate that nucleariids are closely related to fungi. and more distantly to the lineage that gave rise to choanoflagellates and metazoa opisthokonts, the group which includes animals, fungi. Some use a broad definition of Opisthokonta to include all of these organisms with flattened mitochondrial cristae. The genera ''Rabdiophrys'', ''Pinaciophora'', and ''Pompholyxophrys'', freshwater forms with hollow siliceous scales or spines, were included in Nucleariida by some. This was disputed by Smith and Chao who placed them in the Rhizaria. Their affinity with the nucleariids has been confirmed. Historically, nucleariids were included among the heliozoa as the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleariida
Nucleariida is a group of amoebae with filose pseudopods, known mostly from soils and freshwater. They are distinguished from the superficially similar vampyrellids mainly by having mitochondria with discoid cristae, in the absence of superficial granules, and in the way they consume food. Classification Molecular studies indicate that nucleariids are closely related to fungi. and more distantly to the lineage that gave rise to choanoflagellates and metazoa opisthokonts, the group which includes animals, fungi. Some use a broad definition of Opisthokonta to include all of these organisms with flattened mitochondrial cristae. The genera '' Rabdiophrys'', ''Pinaciophora'', and ''Pompholyxophrys'', freshwater forms with hollow siliceous scales or spines, were included in Nucleariida by some. This was disputed by Smith and Chao who placed them in the Rhizaria. Their affinity with the nucleariids has been confirmed. Historically, nucleariids were included among the heliozoa as th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sticholonche
''Sticholonche'' is a genus of radiolarians with a single species, ''Sticholonche zanclea'', found in open oceans at depths of 99–510 metres. It is generally considered a heliozoan, placed in its own order, called the Taxopodida. However it has also been classified as an unusual radiolarian, and this has gained support from genetic studies, which place it near the Acantharea. ''Sticholonche'' are usually around 200 μm, though this varies considerably, and have a bilaterally symmetric shape, somewhat flattened and widened at the front. The axopods are arranged into distinct rows, six of which lie in a dorsal groove and are rigid, and the rest of which are mobile. These are used primarily for buoyancy, rather than feeding. They also have fourteen groups of prominent spines, and many smaller spicule Spicules are any of various small needle-like anatomical structures occurring in organisms Spicule may also refer to: *Spicule (sponge), small skeletal elements of sea sponges ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxopodida
''Sticholonche'' is a genus of radiolarians with a single species, ''Sticholonche zanclea'', found in open oceans at depths of 99–510 metres. It is generally considered a heliozoan, placed in its own order, called the Taxopodida. However it has also been classified as an unusual radiolarian, and this has gained support from genetic studies, which place it near the Acantharea. ''Sticholonche'' are usually around 200 μm, though this varies considerably, and have a bilaterally symmetric shape, somewhat flattened and widened at the front. The axopods are arranged into distinct rows, six of which lie in a dorsal groove and are rigid, and the rest of which are mobile. These are used primarily for buoyancy, rather than feeding. They also have fourteen groups of prominent spines, and many smaller spicule Spicules are any of various small needle-like anatomical structures occurring in organisms Spicule may also refer to: *Spicule (sponge), small skeletal elements of sea sponges ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cercozoa
Cercozoa is a phylum of diverse single-celled eukaryotes. They lack shared morphological characteristics at the microscopic level, and are instead defined by molecular phylogenies of rRNA and actin or polyubiquitin. They were the first major eukaryotic group to be recognized mainly through molecular phylogenies. They are the natural predators of many species of microbacteria and Archea. They are closely related to the phylum Retaria, comprising amoeboids that usually have complex shells, and together form a supergroup called Rhizaria. Characteristics The group includes most amoeboids and flagellates that feed by means of filose pseudopods. These may be restricted to part of the cell surface, but there is never a true cytostome or mouth as found in many other protozoa. They show a variety of forms and have proven difficult to define in terms of structural characteristics, although their unity is strongly supported by phylogenetic studies. Diversity Some cercozoans are grouped ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
