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Choanoflagellates
Choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of animals. The name refers to the characteristic funnel-shaped "collar" of interconnected microvilli and the presence of a flagellum. Choanoflagellates are found globally in aquatic environments, and they are of particular interest to evolutionary biologists studying the origins of multicellularity in animals. The flagellum of choanoflagellates is surrounded by microvilli at its base. Movement of the flagellum creates water currents that can propel free-swimming choanoflagellates through the water column and trap bacteria and detritus against the microvilli, where these foodstuffs are engulfed. This feeding plays an ecological role in the carbon cycle by linking different trophic levels. Choanoflagellates bear morphological similarities to the choanocyte, a type of cell in sponges. As the proposed sister group to Animalia, choanoflagellates s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Choanocyte
Choanocytes (also known as "collar cells") are cells that line the interior of asconoid, syconoid and leuconoid body types of sponges that contain a central flagellum, or ''cilium,'' surrounded by a collar of microvilli which are connected by a thin membrane. They make up the choanoderm, a type of cell layer found in sponges Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and ar .... The cell has the closest resemblance to the choanoflagellates which are the closest related single celled protists to the animal kingdom (metazoans). The flagellae beat regularly, creating a water flow across the microvilli which can then filter nutrients from the water taken from the collar of the sponge. Food particles are then phagocytosed by the cell.Anderson, D. (2001) ''Invertebrate Zoology'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Craspedida
Craspedida is an order of choanoflagellate Choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of animals. The name refers to the characteristic funnel-shaped "collar" of interconnected microvilli and ..., with members with an exclusively organic covering. Crown group craspedids (and perhaps crown group choanoflagellates if Acanthoecida arose within Craspedida) appeared 422.78 million years ago. Although a previous study from 2017 recovered the divergence of the crown group choanoflagellates (craspedids) at 786.62 million years. Craspedid genera ''Codonosiga'' ''Proterospongia'' ''Salpingoeca'' '' Salpingoeca rosetta'' has been named for the rosette-shaped colonies formed by its cells. Recent studies show a bacterial sulfonolipid, called rosette inducing factor (RIF-1) produced by '' Algoriphagus machipongonensis'' triggers colony formation in ''S. rosetta''. References * Extende ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acanthoecida
Acanthoecida is an order of Choanoflagellates Choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of animals. The name refers to the characteristic funnel-shaped "collar" of interconnected microvilli and t ... belonging to the class Choanoflagellatea.. It is a type of heterotrophic nanoflagellate that feeds on suspended particles. Families: * Acanthoecidae Norris, 1965 * Stephanoecidae Leadbeater in Nitsche et al., 2011 References External links * https://doi.org/10.1017/CBO9781139051125.011 Choanoflagellate orders Opisthokont orders {{holozoa-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flagellate
A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and their means of motion. The term presently does not imply any specific relationship or classification of the organisms that possess flagella. However, several derivations of the term "flagellate" (such as " dinoflagellate" and " choanoflagellate") are more formally characterized. Form and behavior Flagella in eukaryotes are supported by microtubules in a characteristic arrangement, with nine fused pairs surrounding two central singlets. These arise from a basal body. In some flagellates, flagella direct food into a cytostome or mouth, where food is ingested. Flagella role in classifying eukaryotes. Among protoctists and microscopic animals, a flagellate is an organism with one or more flagella. Some cells in other animals may be flage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multicellularity
A multicellular organism is an organism that consists of more than one cell, unlike unicellular organisms. All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- and partially multicellular, like slime molds and social amoebae such as the genus '' Dictyostelium''. Multicellular organisms arise in various ways, for example by cell division or by aggregation of many single cells. Colonial organisms are the result of many identical individuals joining together to form a colony. However, it can often be hard to separate colonial protists from true multicellular organisms, because the two concepts are not distinct; colonial protists have been dubbed "pluricellular" rather than "multicellular". There are also macroscopic organisms that are multinucleate though technically unicellular, such as the Xenophyophorea that can reach 20 cm. Evolutionary history Occurrence Multicellularity has evolved ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sponge
Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and are one of the most ancient members of macrobenthos, with many historical species being important reef-building organisms. Sponges are multicellular organisms consisting of jelly-like mesohyl sandwiched between two thin layers of cells, and usually have tube-like bodies full of pores and channels that allow water to circulate through them. They have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process. They do not have complex nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes, usually via flagella movements of the so-called " collar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Codonosigidae
Codonosigidae were a choanoflagellate Choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of animals. The name refers to the characteristic funnel-shaped "collar" of interconnected microvilli and ... family. In the newest taxonomy the family Codonsigidae is replaced by the Salpingoecidae. References Opisthokont families Choanoflagellate families {{Holozoa-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salpingoecidae
Salpingoecidae is a family of Choanoflagellate Choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of animals. The name refers to the characteristic funnel-shaped "collar" of interconnected microvilli and ...s. References External links * * Choanoflagellate families Opisthokont families {{Holozoa-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acanthoecidae
Acanthoecidae is a family of choanoflagellates. Its subgroups Diaphanoeca and Stephanoeca bear lorica composed of silica which possibly originate from diatoms via horizontal gene transfer Horizontal gene transfer (HGT) or lateral gene transfer (LGT) is the movement of genetic material between organisms other than by the ("vertical") transmission of DNA from parent to offspring (reproduction). HGT is an important factor in the e .... Genera '' Acanthocorbis'' - '' Acanthoeca'' - '' Amoenoscopa'' - '' Apheloecion'' - '' Bicosta'' - '' Calliacantha'' - '' Calotheca'' - '' Campyloacantha'' - '' Conion'' - '' Cosmoeca'' - '' Crinolina'' - '' Crucispina'' - '' Diaphanoeca'' - '' Diplotheca'' - '' Kakoeca'' - '' Monocosta'' - '' Nannoeca'' - '' Parvicorbicula'' - '' Platypleura'' - '' Pleurasiga'' - '' Polyfibula'' - '' Polyoeca'' - '' Saepicula'' - '' Saroeca'' - '' Savillea'' - '' Spiraloecion'' - '' Stephanacantha'' - '' Stephanoeca'' - '' Syndetophyllum'' References Ext ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sister Group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and taxon B are sister groups to each other. Taxa A and B, together with any other extant or extinct descendants of their most recent common ancestor (MRCA), form a monophyletic group, the clade AB. Clade AB and taxon C are also sister groups. Taxa A, B, and C, together with all other descendants of their MRCA form the clade ABC. The whole clade ABC is itself a subtree of a larger tree which offers yet more sister group relationships, both among the leaves and among larger, more deeply rooted clades. The tree structure shown connects through its root to the rest of the universal tree of life. In cladistic standards, taxa A, B, and C may represent specimens, species, genera, or any other taxonomic units. If A and B are at the same taxono ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hybrid Word
A hybrid word or hybridism is a word that etymologically derives from at least two languages. Such words are a type of macaronic language. Common hybrids The most common form of hybrid word in English combines Latin and Greek parts. Since many prefixes and suffixes in English are of Latin or Greek etymology, it is straightforward to add a prefix or suffix from one language to an English word that comes from a different language, thus creating a hybrid word. Hybridisms were formerly often considered to be barbarisms., ''s.v.'' 'barbarism' English examples * Antacid – from Greek () 'against' and Latin acidus 'acid'; this term dates back to 1732. * Aquaphobia – from Latin 'water' and Greek () 'fear'; this term is distinguished from the non-hybrid word '' hydrophobia'', a historical term for rabies and one of its main symptoms. * Asexual – from Greek prefix 'without' and the Latin ' sex' * Automobile – a wheeled passenger vehicle, from Greek () 'self' and Lat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
