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Livebearers
Livebearers are aquarium fish that retain the eggs inside the body and give birth to live, free-swimming young. Among aquarium fish, livebearers are nearly all members of the family Poeciliidae and include guppies, mollies, platies and swordtails. The advantages of livebearing to the aquarist are that the newborn juvenile fish are larger than newly-hatched fry, have a lower chance of mortality and are easier to care for. Unusual livebearers include seahorses and pipefish, where the males care for the young, and certain cichlids that are mouthbrooders, with the parent incubating the eggs in the buccal cavity. Common aquarium livebearers Species of interest to aquarists are almost always members of the family Poeciliidae, most commonly guppies, mollies, platies, swordtails, Endler's livebearer, and mosquito fish. Most of these are ovoviviparous, with the developing embryos receiving no nourishment from the parent fish, but a few are viviparous, receiving food from the maternal blo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swordtail
''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 e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poeciliidae
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 ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guppies
The guppy (), also known as millionfish and rainbow fish, is one of the world's most widely distributed tropical fish and one of the most popular freshwater aquarium fish species. It is a member of the family Poeciliidae and, like almost all American members of the family, is live-bearing. Guppies originate from northeast South America, but have been introduced to many environments and are now found all over the world. They are highly adaptable and thrive in many different environmental and ecological conditions. Male guppies, which are smaller than females, have ornamental caudal and dorsal fins. Wild guppies generally feed on a variety of food sources, including benthic algae and aquatic insect larvae. Guppies are used as a model organism in the fields of ecology, evolution, and behavioural studies. Taxonomy Guppies were first described in Venezuela as ''Poecilia reticulata'' by Wilhelm Peters in 1859 and as ''Lebistes poecilioides'' in Barbados by De Filippi in 1861. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endler's Livebearer
''Poecilia wingei'', known to aquarists as Endlers or Endler's livebearer, in the genus ''Poecilia'', is a small fish native to the Paria Peninsula in Venezuela. They are prolific breeders and often hybridize with guppies. These very colorful hybrids are the easiest to find being offered in pet-shops, typically under the name Endler's guppy. History ''Poecilia wingei'' is a very colorful guppy species, similar to the fancy guppy often found in pet shops. The species was first collected from Laguna de Patos in Venezuela by Franklyn F. Bond in 1937, and rediscovered by Dr. John Endler in 1975. The latter were the first examples of this fish to make it to the aquarium trade. More have been collected since then, notably by Armando Pou, to expand the captive breeding stock. The original Laguna de Patos population is threatened by runoff from a municipal garbage dump. Though it is rare in pet shops, this species is seen occasionally in the aquaria of enthusiasts. Although not yet t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poecilia Reticulata Fry DSC04357 Nevit
''Poecilia'' is a genus of fishes in the family Poeciliidae of the order Cyprinodontiformes. These livebearers are native to fresh, brackish and salt water in the Americas, and some species in the genus are euryhaline. A few have adapted to living in waters that contain high levels of toxic hydrogen sulfide ()Palacios, Arias-Rodriguez, Plath, Eifert, Lerp, Lamboj, Voelker, & Tobler (2013). The Rediscovery of a Long Described Species Reveals Additional Complexity in Speciation Patterns of Poeciliid Fishes in Sulfide Springs.' PLoS ONE 8(8): e71069. and a population of '' P. mexicana'' lives in caves (other populations of this species are surface-living). Some common and widespread species are often kept as aquarium fish, while other have very small ranges and are seriously threatened. All species in ''Poecilia'' are called mollies except for the Endler's livebearer (''P. wingei'') and the well-known guppy (''P. reticulata'') which have a distinctly different body shape from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placental Mammals
Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguished from monotremes and marsupials in that the fetus is carried in the uterus of its mother to a relatively late stage of development. The name is something of a misnomer considering that marsupials also nourish their fetuses via a placenta, though for a relatively briefer period, giving birth to less developed young which are then nurtured for a period inside the mother's pouch. Anatomical features Placental mammals are anatomically distinguished from other mammals by: * a sufficiently wide opening at the bottom of the pelvis to allow the birth of a large baby relative to the size of the mother. * the absence of epipubic bones extending forward from the pelvis, which are found in all other mammals. (Their function in non-placental mammals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ovoviviparous
Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop inside eggs that remain in the mother's body until they are ready to hatch. The young of some ovoviviparous amphibians, such as '' Limnonectes larvaepartus'', are born as larvae, and undergo further metamorphosis outside the body of the mother. Members of genera '' Nectophrynoides'' and '' Eleutherodactylus'' bear froglets, not only the hatching, but all the most conspicuous metamorphosis, being completed inside the body of the mother before birth. Among insects that depend on opportunistic exploitation of transient food sources, such as many Sarcophagidae and other carrion flies, and species such as many Calliphoridae, that rely on fresh dung, and parasitoids such as tachinid flies that depend on entering the host as soon as possible ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viviparous
Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the mother. The term 'viviparity' and its adjective form 'viviparous' derive from the Latin ''vivus'' meaning "living" and ''pario'' meaning "give birth to". Reproductive mode Five modes of reproduction have been differentiated in animals based on relations between zygote and parents. The five include two nonviviparous modes: ovuliparity, with external fertilisation, and oviparity, with internal fertilisation. In the latter, the female lays zygotes as eggs with a large yolk; this occurs in all birds, most reptiles, and some fishes. These modes are distinguished from viviparity, which covers all the modes that result in live birth: *Histotrophic viviparity: the zygotes develop in the female's oviducts, but find their nutrients by oopha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oviparity
Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and monotremes. In traditional usage, most insects (one being '' Culex pipiens'', or the common house mosquito), molluscs, and arachnids are also described as oviparous. Modes of reproduction The traditional modes of reproduction include oviparity, taken to be the ancestral condition, traditionally where either unfertilised oocytes or fertilised eggs are spawned, and viviparity traditionally including any mechanism where young are born live, or where the development of the young is supported by either parent in or on any part of their body. However, the biologist Thierry Lodé recently divided the traditional category of oviparous reproduction into two modes that he named ovuliparity and (true) oviparity respectively. He distinguished ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placenta
The placenta is a temporary embryonic and later fetal organ (anatomy), organ that begins embryonic development, developing from the blastocyst shortly after implantation (embryology), implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate maternal and fetal circulations, and is an important Endocrine system, endocrine organ, producing hormones that regulate both Maternal physiological changes in pregnancy, maternal and fetal physiology during pregnancy. The placenta connects to the fetus via the umbilical cord, and on the opposite aspect to the maternal uterus in a species-dependent manner. In humans, a thin layer of maternal decidual (Endometrium, endometrial) tissue comes away with the placenta when it is expelled from the uterus following birth (sometimes incorrectly referred to as the 'maternal part' of the placenta). Placentas are a defining characteristic of placental mammals, but are also found in marsupials an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analogy (biology)
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is homoplasy. The recurrent evolution of flight is a classic example, as flying insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are ''analogous'', whereas ''homologous'' structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different traits. Convergent evolution is similar to parallel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seahorse (fish)
A seahorse (also written ''sea-horse'' and ''sea horse'') is any of 46 species of small marine fish in the genus ''Hippocampus''. "Hippocampus" comes from the Ancient Greek (), itself from () meaning "horse" and () meaning "sea monster" or "sea animal". Having a head and neck suggestive of a horse, seahorses also feature segmented bony armour, an upright posture and a curled prehensile tail. Along with the pipefishes and seadragons ('' Phycodurus'' and '' Phyllopteryx'') they form the family Syngnathidae. Habitat Seahorses are mainly found in shallow tropical and temperate salt water throughout the world, from about 45°S to 45°N. They live in sheltered areas such as seagrass beds, estuaries, coral reefs, and mangroves. Four species are found in Pacific waters from North America to South America. In the Atlantic, '' Hippocampus erectus'' ranges from Nova Scotia to Uruguay. '' H. zosterae'', known as the dwarf seahorse, is found in the Bahamas. Colonies have been found in E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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