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Xiphophorus Cortezi
''Xiphophorus cortezi'', the delicate swordtail, is a species of poeciliid fish from Mexico. Named after the Spanish ''conquistador'' Hernán Cortés, ''Xiphophorus cortezi'' was originally described in 1960 by Donn Eric Rosen as a subspecies of '' X. montezumae''. It was well known in literature prior to the formal scientific description. The smaller males of ''X. cortezi'' are similar to the larger males of '' X. nigrensis'', pointing to a close evolutionary relationship with this species too. Adult size is variable and averages about 30 mm in standard length. The color of the male, especially the midlateral stripe, depends on the excitement of the fish and background shade of its environment. Some specimens kept in the laboratory for years have shown such silvery coloring that black markings became absent. Different patterns of black spots on the tail exist. ''Xiphophorus cortezi'' is found in the upper Rio Panuco system in northeastern Mexico. Two congeners, '' X. pygmaeus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Donn Eric Rosen
Donn Eric Rosen (1929-1986) was a member of the staff of the American Museum of Natural History. He was a Distinguished Fellow of the American Society of Ichthyologists and Herpetologists. Family Born to immigrants Irwin Rosen (b. 1885) and Anita Gerber Rosen (b. 1906), Rosen has an older brother : Charles Welles. Both his parents were born in Russia. Irwin came to the United States in 1889 and had a career in architecture. Anita arrived in the United States prior to 1920. Works Rosen has written over twenty eight scientific papers. Rosen has described twenty three species. Selected publications *Rosen, Donn Eric, P. Humphry Greenwood 1970. Origin of the Weberian Apparatus and the Relationships of the Ostariophysan and Gonorynchiform Fishes, American Museum Novitates, American Museum of Natural History,New York, New York, USA, 2428 *Rosen, Donn Eric, Bailey, Reeve M. The Poeciliid Fishes (Cyprinodontiformes), Their Structure, Zoogeography, and Systematics. Bulletin of the A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Congener (biology)
Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organisms or constituents of living organisms of being special or doing something special. Each animal or plant species is special. It differs in some way from all other species...biological specificity is the major problem about understanding life." Biological specificity within ''Homo sapiens'' ''Homo sapiens'' has many characteristics that show the biological specificity in the form of behavior and morphological traits. Morphologically, humans have an enlarged cranial capacity and more gracile features in comparison to other hominins. The reduction of dentition is a feature that allows for the advantage of adaptability in diet and survival. As a species, humans are culture dependent and much of human survival relies on the culture and so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endemic Fish Of Mexico
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, the Cape sugarbird is found exclusively in southwestern South Africa and is therefore said to be ''endemic'' to that particular part of the world. An endemic species can be also be referred to as an ''endemism'' or in scientific literature as an ''endemite''. For example '' Cytisus aeolicus'' is an endemite of the Italian flora. '' Adzharia renschi'' was once believed to be an endemite of the Caucasus, but it was later discovered to be a non-indigenous species from South America belonging to a different genus. The extreme opposite of an endemic species is one with a cosmopolitan distribution, having a global or widespread range. A rare alternative term for a species that is endemic is "precinctive", which applies to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freshwater Fish Of Mexico
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include non- salty mineral-rich waters such as chalybeate springs. Fresh water may encompass frozen and meltwater in ice sheets, ice caps, glaciers, snowfields and icebergs, natural precipitations such as rainfall, snowfall, hail/ sleet and graupel, and surface runoffs that form inland bodies of water such as wetlands, ponds, lakes, rivers, streams, as well as groundwater contained in aquifers, subterranean rivers and lakes. Fresh water is the water resource that is of the most and immediate use to humans. Water is critical to the survival of all living organisms. Many organisms can thrive on salt water, but the great majority of higher plants and most insects, amphibians, reptiles, mammals and birds need fresh water to survive. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xiphophorus
''Xiphophorus'' is a genus of euryhaline and freshwater fishes in the family Poeciliidae of order Cyprinodontiformes, native to Mexico and northern Central America. The many ''Xiphophorus'' species are all known as platyfish (or platies) and swordtails. Platyfish formerly were classified in another genus, ''Platypoecilia'', which is now obsolete. The type species is ''X. hellerii,'' the green swordtail. Like most other new world Poeciliids, platies and swordtails are live-bearers that use internal fertilization and give birth to live young instead of laying eggs like the bulk of the world's fishes. The name ''Xiphophorus'' derives from the Greek words ξίφος (dagger) and φόρος (bearer), referring to the gonopodium on the males. All are relatively small fishes, which reach a maximum length of depending on the exact species involved. Distribution and conservation status The various ''Xiphophorus'' species range from the southern Rio Grande basin in Mexico, through ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecological Niche
In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (for example, by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (for example, limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey). "The type and number of variables comprising the dimensions of an environmental niche vary from one species to another ndthe relative importance of particular environmental variables for a species may vary according to the geographic and biotic contexts". See also Chapter 2: Concepts of niches, pp. 7 ''ff'' A Grinnellian niche is determined by the habitat in which a species lives and its accompanying behavioral adaptations. An Eltonian niche emphasizes that a spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rio Axtla
Rio or Río is the Portuguese, Spanish, Italian, and Maltese word for "river". When spoken on its own, the word often means Rio de Janeiro, a major city in Brazil. Rio or Río may also refer to: Geography Brazil * Rio de Janeiro * Rio do Sul, a town in the state of Santa Catarina, Brazil Mexico * Río Bec, a Mayan archaeological site in Mexico * Río Bravo, Tamaulipas, a city in Mexico United States * Rio, a location in Deerpark, New York, US * Rio, Florida, a census-designated place in Martin County, US * Rio, Georgia, an unincorporated community in Spalding County, US * Rio, Illinois, a village in Knox County, US * Rio, Virginia, a community in Albemarle County, US * Rio, West Virginia, a village in Hampshire County, US * Rio, Wisconsin, a village in Columbia County, US * El Río, Las Piedras, Puerto Rico, a barrio * Río Arriba, Añasco, Puerto Rico, a barrio * Río Arriba, Arecibo, Puerto Rico, a barrio * Río Arriba, Fajardo, Puerto Rico, a barrio * Río Arriba, Vega Baja, Pu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xiphophorus Variatus
''Xiphophorus'' is a genus of euryhaline and freshwater fishes in the family Poeciliidae of order (biology), order Cyprinodontiformes, native to Mexico and northern Central America. The many ''Xiphophorus'' species are all known as platyfish (or platies) and swordtails. Platyfish formerly were classified in another genus, ''Platypoecilia'', which is now obsolete. The type species is ''X. hellerii,'' the green swordtail. Like most other new world Poeciliids, platies and swordtails are Livebearers, live-bearers that use internal fertilization and give birth to live young instead of laying eggs like the bulk of the world's fishes. The name ''Xiphophorus'' derives from the Greek language, Greek words ξίφος (dagger) and φόρος (bearer), referring to the Fish fin#Reproduction, gonopodium on the males. All are relatively small fishes, which reach a maximum length of depending on the exact species involved. Distribution and conservation status The various ''Xiphophorus'' s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xiphophorus Pygmaeus
''Xiphophorus pygmaeus'', the pygmy swordtail, is a poeciliid fish from northeastern Mexico. It is the smallest of the swordtails. The male's sword is barely visible and the species is often called the swordless swordtail. It is sometimes kept in home aquaria, but is a rather delicate species. Taxonomy and evolution ''Xiphophorus pygmaeus'' is the smallest member of the genus ''Xiphophorus''. It is most closely related to '' X. multilineatus'' and '' X. nigrensis'', and males in particular look similar to the small males of the latter two species. The three species form a clade within the larger clade of northern swordtails. ''X. pygmaeus'' lost large-sized males and male traits associated with larger size: courtship behavior, body depth, and well-developed swords. Large size eventually reappeared in ''X. pygmaeus'' but the normally accompanying traits did not. Description Females grow to , while males attain . The male's sword is only 1-2 mm long. The species was originally thou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rio Panuco
Rio or Río is the Portuguese, Spanish, Italian, and Maltese word for "river". When spoken on its own, the word often means Rio de Janeiro, a major city in Brazil. Rio or Río may also refer to: Geography Brazil * Rio de Janeiro * Rio do Sul, a town in the state of Santa Catarina, Brazil Mexico * Río Bec, a Mayan archaeological site in Mexico * Río Bravo, Tamaulipas, a city in Mexico United States * Rio, a location in Deerpark, New York, US * Rio, Florida, a census-designated place in Martin County, US * Rio, Georgia, an unincorporated community in Spalding County, US * Rio, Illinois, a village in Knox County, US * Rio, Virginia, a community in Albemarle County, US * Rio, West Virginia, a village in Hampshire County, US * Rio, Wisconsin, a village in Columbia County, US * El Río, Las Piedras, Puerto Rico, a barrio * Río Arriba, Añasco, Puerto Rico, a barrio * Río Arriba, Arecibo, Puerto Rico, a barrio * Río Arriba, Fajardo, Puerto Rico, a barrio * Río Arriba, Vega Baja ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poeciliid
The Poeciliidae are a family of freshwater fishes of the order Cyprinodontiformes, the tooth-carps, and include well-known live-bearing aquarium fish, such as the guppy, molly, platy, and swordtail. The original distribution of the family was the Southeastern United States to north of Río de la Plata, Argentina, and Africa, including Madagascar. Due to release of aquarium specimens and the widespread use of species of the genera ''Poecilia'' and ''Gambusia'' for mosquito control, though, poeciliids can today be found in all tropical and subtropical areas of the world. In addition, ''Poecilia'' and ''Gambusia'' specimens have been identified in hot springs pools as far north as Banff, Alberta. Live-bearing Although the whole family Poeciliidae is known as "live bearers" (viviparous), some species are egg-scattering with external fertilization. All African species are egg-layers, and (with the exception of the members of the genus ''Tomeurus''), all American species are live ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melanophore
Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and birds, in contrast, have a class of cells called melanocytes for coloration. Chromatophores are largely responsible for generating skin and eye colour in ectothermic animals and are generated in the neural crest during embryonic development. Mature chromatophores are grouped into subclasses based on their colour (more properly "hue") under white light: xanthophores (yellow), erythrophores (red), iridophores (reflective / iridescent), leucophores (white), melanophores (black/brown), and cyanophores (blue). While most chromatophores contain pigments that absorb specific wavelengths of light, the color of leucophores and iridophores is produced by their respective scattering and optical interference properties. Some species can rapidly change colour through ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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