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Tilapia Guinasana
The Otjikoto tilapia (''Tilapia guinasana'') is a critically endangered species of cichlid fish endemic to Namibia where it was originally only found in Lake Guinas. This very small sinkhole lake contains quite clear water that generally ranges between depending on season,van Jaarsveld, E. (December 2013)Otjikoto Tilapia. South African National Biodiversity Institute. Retrieved 18 April 2017. and the Otjikoto tilapia has been seen down to depths of . Despite deriving its common name from the nearby Lake Otjikoto, it in not native to that lake, rather being an introduced species. It is rare in the aquarium tradeSeriouslyFishTilapia guinasana.Retrieved 18 April 2017. and also kept in garden ponds in southern Africa. It is shoaling, but when breeding the pairs separate out, moving to the lake's vertical cliff edges where narrow ledges are used for breeding. The eggs and young are aggressively guarded by the parents. The Otjikoto tilapia mostly feeds on algae, including diatoms, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethelwynn Trewavas
Ethelwynn Trewavas (5 November 1900 – 16 August 1993) was an ichthyologist at the British Museum of Natural History. She was known for her work on the families Cichlidae and Sciaenidae. She worked with Charles Tate Regan, another ichthyologist and taxonomist. Academic studies and career She received her bachelor's degree and Board of Education Certificate in Teaching in 1921 from Reading University, and then worked as a teacher before being employed by the King's College of Household and Social Science as a part-time demonstrator, spending most of her time on research. She was taught by Dr. Nellie B. Eales when associated with the Freshwater Biological Association. She met Charles Regan and was employed by him as his assistant until hired by the British Museum (Natural History) as Assistant Keeper in 1935. She was appointed Deputy Keeper of Zoology in 1958, and retired in 1961. She served as the senior scientist in the Fish Section of the British Museum (Natural Histo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish Measurement
Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish measured from the tip of the snout to the posterior end of the last vertebra or to the posterior end of the midlateral portion of the hypural plate. Simply put, this measurement excludes the length of the caudal (tail) fin. * Total length (TL) is the length of a fish measured from the tip of the snout to the tip of the longer lobe of the caudal fin, usually measured with the lobes compressed along the midline. It is a straight-line measure, not measured over the curve of the body. Standard length measurements are used with Teleostei (most bony fish), while total length measurements are used with Myxini (hagfish), Petromyzontiformes (lampreys), and (usually) Elasmobranchii (sharks and rays), as well as some other fishes. Total length meas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endemic Fauna Of Namibia
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 (ecology), 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, Cytisus aeolicus'' is an endemite of the Italian flora. ''Enidae, Adzharia renschi'' was once believed to be an endemite of the Caucasus, but it was later discovered to be a Invasive species, 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 specie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freshwater Fish Of Namibia
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. Fresh water is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cichlid Fish Of Africa
This is a list of African cichlid species that are commonly kept by aquarist An aquarist is a person who manages aquariums, either professionally or as a hobby. They typically care for aquatic animals, including fish and marine invertebrates. Some may care for aquatic mammals. Aquarists often work at public aquariums. They ...s. Another African cichlid is a Frontosa (Cyphotilapia frontosa) which is commonly found in Lake Tanganyika. It grows to about 10-14 inches has minimal aggression and is stripy. References {{reflist ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tilapia
Tilapia ( ) is the common name for nearly a hundred species of cichlid fish from the coelotilapine, coptodonine, heterotilapine, oreochromine, pelmatolapiine, and tilapiine tribes (formerly all were "Tilapiini"), with the economically most important species placed in the Coptodonini and Oreochromini. Tilapia are mainly freshwater fish inhabiting shallow streams, ponds, rivers, and lakes, and less commonly found living in brackish water. Historically, they have been of major importance in artisanal fishing in Africa, and they are of increasing importance in aquaculture and aquaponics. Tilapia can become a problematic invasive species in new warm-water habitats such as Australia, whether deliberately or accidentally introduced, but generally not in temperate climates due to their inability to survive in cold water. Tilapia has been the fourth-most consumed fish in the United States since 2002. The popularity of tilapia came about due to its low price, easy preparation, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interbreed
In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents (such as in blending inheritance), but can show hybrid vigor, sometimes growing larger or taller than either parent. The concept of a hybrid is interpreted differently in animal and plant breeding, where there is interest in the individual parentage. In genetics, attention is focused on the numbers of chromosomes. In taxonomy, a key question is how closely related the parent species are. Species are reproductively isolated by strong barriers to hybridisation, which include genetic and morphological differences, differing times of fertility, mating behaviors and cues, and physiological rejection of sperm cells or the developing embryo. Some act before fertilization and others after it. Similar barriers exist in plants, with differences in flowering tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Banded Tilapia
''Tilapia sparrmanii'', the banded tilapia, or vlei kurper, is a widespread and adaptable cichlid fish that is found in warmer freshwater habitats of southern Africa. They prefer water with ample plant cover, and occur naturally as far north as DR Congo and Tanzania. They have been introduced locally in the northern hemisphere. Younger banded tilapia feed on crustaceans and insect larvae, while the adults feed on terrestrial and aquatic plants and other debris. They undertake local migrations and may shoal before and during spawning time. They guard their own eggs, and although they may move eggs or fry in the mouth, they are not known to be actual mouthbrooders like several other tilapia species. This species can reach a length of TL and is an important foodfish. The identity of the person honoured in the specific name is uncertain but it is probably the Swedish naturalist Anders Sparrman (1748-1820) who was in the Cape A cape is a clothing accessory or a sleeveless out ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nguni Cattle
The Nguni is a cattle breed indigenous to Southern Africa. A hybrid of different Indian and later European cattle breeds, they were introduced by pastoralist tribes ancestral to modern Nguni people to Southern Africa during their migration from the North of the continent. The cattle breed is medium-sized and adapted to grazing on the highveld. Characteristics Nguni cattle are known for their fertility and resistance to diseases, being the favourite breed amongst the local Bantu-speaking people of southern Africa (South Africa, Eswatini, Namibia, Zimbabwe, Botswana, and Angola). They are characterised by their multicoloured skin, which can present many different patterns, but their noses are always black-tipped. They are a principal form of Sanga cattle, which originated as hybrids of Zebu and humpless cattle in East Africa. DNA analyses have confirmed that they are a combination of '' Bos indicus'' and ''Bos taurus'', that is a combination of different Zebu and European cattle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Assortative Mating
Assortative mating (also referred to as positive assortative mating or homogamy) is a mating pattern and a form of sexual selection in which individuals with similar phenotypes or genotypes mate with one another more frequently than would be expected under a random mating pattern. A majority of the phenotypes that are subject to assortative mating are body size, visual signals (e.g. color, pattern), and sexually selected traits such as crest size. The opposite of assortative is disassortative mating. Causes Several hypotheses have been proposed to explain the phenomenon of assortative mating. Assortative mating has evolved from a combination of different factors, which vary across different species. Assortative mating with respect to body size can arise as a consequence of intrasexual competition. In some species, size is correlated with fecundity in females. Therefore, males choose to mate with larger females, with the larger males defeating the smaller males in courting the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetics
Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar working in the 19th century in Brno, was the first to study genetics scientifically. Mendel studied "trait inheritance", patterns in the way traits are handed down from parents to offspring over time. He observed that organisms (pea plants) inherit traits by way of discrete "units of inheritance". This term, still used today, is a somewhat ambiguous definition of what is referred to as a gene. Trait inheritance and molecular inheritance mechanisms of genes are still primary principles of genetics in the 21st century, but modern genetics has expanded to study the function and behavior of genes. Gene structure and function, variation, and distribution are studied within the context of the cell, the organism (e.g. dominance), and within the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Dimorphism
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most animals and some plants. Differences may include secondary sex characteristics, size, weight, colour, markings, or behavioural or cognitive traits. These differences may be subtle or exaggerated and may be subjected to sexual selection and natural selection. The opposite of dimorphism is ''monomorphism'', which is when both biological sexes are phenotypically indistinguishable from each other. Overview Ornamentation and coloration Common and easily identified types of dimorphism consist of ornamentation and coloration, though not always apparent. A difference in coloration of sexes within a given species is called sexual dichromatism, which is commonly seen in many species of birds and reptiles. Sexual selection leads to the exaggerated dim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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