1.
Taxonomy (biology)
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Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups. The exact definition of taxonomy varies from source to source, but the core of the remains, the conception, naming. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy, the broadest meaning of taxonomy is used here. The word taxonomy was introduced in 1813 by Candolle, in his Théorie élémentaire de la botanique, the term alpha taxonomy is primarily used today to refer to the discipline of finding, describing, and naming taxa, particularly species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, ideals can, it may be said, never be completely realized. They have, however, a value of acting as permanent stimulants. Some of us please ourselves by thinking we are now groping in a beta taxonomy, turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology, genetics, and cytology. He further excludes phylogenetic reconstruction from alpha taxonomy, thus, Ernst Mayr in 1968 defined beta taxonomy as the classification of ranks higher than species. This activity is what the term denotes, it is also referred to as beta taxonomy. How species should be defined in a group of organisms gives rise to practical and theoretical problems that are referred to as the species problem. The scientific work of deciding how to define species has been called microtaxonomy, by extension, macrotaxonomy is the study of groups at higher taxonomic ranks, from subgenus and above only, than species. While some descriptions of taxonomic history attempt to date taxonomy to ancient civilizations, earlier works were primarily descriptive, and focused on plants that were useful in agriculture or medicine. There are a number of stages in scientific thinking. Early taxonomy was based on criteria, the so-called artificial systems. Later came systems based on a complete consideration of the characteristics of taxa, referred to as natural systems, such as those of de Jussieu, de Candolle and Bentham. The publication of Charles Darwins Origin of Species led to new ways of thinking about classification based on evolutionary relationships and this was the concept of phyletic systems, from 1883 onwards. This approach was typified by those of Eichler and Engler, the advent of molecular genetics and statistical methodology allowed the creation of the modern era of phylogenetic systems based on cladistics, rather than morphology alone. Taxonomy has been called the worlds oldest profession, and naming and classifying our surroundings has likely been taking place as long as mankind has been able to communicate
2.
Animal
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Animals are multicellular, eukaryotic organisms of the kingdom Animalia. The animal kingdom emerged as a clade within Apoikozoa as the group to the choanoflagellates. Animals are motile, meaning they can move spontaneously and independently at some point in their lives and their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later in their lives. All animals are heterotrophs, they must ingest other organisms or their products for sustenance, most known animal phyla appeared in the fossil record as marine species during the Cambrian explosion, about 542 million years ago. Animals can be divided broadly into vertebrates and invertebrates, vertebrates have a backbone or spine, and amount to less than five percent of all described animal species. They include fish, amphibians, reptiles, birds and mammals, the remaining animals are the invertebrates, which lack a backbone. These include molluscs, arthropods, annelids, nematodes, flatworms, cnidarians, ctenophores, the study of animals is called zoology. The word animal comes from the Latin animalis, meaning having breath, the biological definition of the word refers to all members of the kingdom Animalia, encompassing creatures as diverse as sponges, jellyfish, insects, and humans. Aristotle divided the world between animals and plants, and this was followed by Carl Linnaeus, in the first hierarchical classification. In Linnaeuss original scheme, the animals were one of three kingdoms, divided into the classes of Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. Since then the last four have all been subsumed into a single phylum, in 1874, Ernst Haeckel divided the animal kingdom into two subkingdoms, Metazoa and Protozoa. The protozoa were later moved to the kingdom Protista, leaving only the metazoa, thus Metazoa is now considered a synonym of Animalia. Animals have several characteristics that set apart from other living things. Animals are eukaryotic and multicellular, which separates them from bacteria and they are heterotrophic, generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungi by lacking cell walls. All animals are motile, if only at life stages. In most animals, embryos pass through a stage, which is a characteristic exclusive to animals. With a few exceptions, most notably the sponges and Placozoa and these include muscles, which are able to contract and control locomotion, and nerve tissues, which send and process signals
3.
Chordate
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Chordates are deuterostomes, as during the embryo development stage the anus forms before the mouth. They are also bilaterally symmetric coelomates, in the case of vertebrate chordates, the notochord is usually replaced by a vertebral column during development, and they may have body plans organized via segmentation. There are also additional extinct taxa, the Vertebrata are sometimes considered as a subgroup of the clade Craniata, consisting of chordates with a skull, the Craniata and Tunicata compose the clade Olfactores. Of the more than 65,000 living species of chordates, the worlds largest and fastest animals, the blue whale and peregrine falcon respectively, are chordates, as are humans. Fossil chordates are known from at least as early as the Cambrian explosion, Hemichordata, which includes the acorn worms, has been presented as a fourth chordate subphylum, but it now is usually treated as a separate phylum. The Hemichordata, along with the Echinodermata, form the Ambulacraria, the Chordata and Ambulacraria form the superphylum Deuterostomia, composed of the deuterostomes. Attempts to work out the relationships of the chordates have produced several hypotheses. All of the earliest chordate fossils have found in the Early Cambrian Chengjiang fauna. Because the fossil record of early chordates is poor, only molecular phylogenetics offers a prospect of dating their emergence. However, the use of molecular phylogenetics for dating evolutionary transitions is controversial and it has also proved difficult to produce a detailed classification within the living chordates. Attempts to produce family trees shows that many of the traditional classes are paraphyletic. While this has been known since the 19th century, an insistence on only monophyletic taxa has resulted in vertebrate classification being in a state of flux. Although the name Chordata is attributed to William Bateson, it was already in prevalent use by 1880, ernst Haeckel described a taxon comprising tunicates, cephalochordates, and vertebrates in 1866. Though he used the German vernacular form, it is allowed under the ICZN code because of its subsequent latinization, among the vertebrate sub-group of chordates the notochord develops into the spine, and in wholly aquatic species this helps the animal to swim by flexing its tail. In fish and other vertebrates, this develops into the spinal cord, the pharynx is the part of the throat immediately behind the mouth. In fish, the slits are modified to form gills, a muscular tail that extends backwards behind the anus. This is a groove in the wall of the pharynx. In filter-feeding species it produces mucus to gather food particles, which helps in transporting food to the esophagus and it also stores iodine, and may be a precursor of the vertebrate thyroid gland
4.
Actinopterygii
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Actinopterygii /ˌæktᵻnˌɒptəˈrɪdʒi. aɪ/, or the ray-finned fishes, constitute a class or subclass of the bony fishes. These actinopterygian fin rays attach directly to the proximal or basal skeletal elements, the radials, numerically, actinopterygians are the dominant class of vertebrates, comprising nearly 99% of the over 30,000 species of fish. They are ubiquitous throughout freshwater and marine environments from the sea to the highest mountain streams. Extant species can range in size from Paedocypris, at 8 mm, to the ocean sunfish, at 2,300 kg. Ray-finned fishes occur in variant forms. The main features of a typical ray-finned fish are shown in the diagram at the left. In nearly all ray-finned fish, the sexes are separate, development then proceeds with a free-swimming larval stage. However other patterns of ontogeny exist, with one of the commonest being sequential hermaphroditism, in most cases this involves protogyny, fish starting life as females and converting to males at some stage, triggered by some internal or external factor. This may be advantageous as females become less prolific as they age while male fecundity increases with age, protandry, where a fish converts from male to female, is much less common than protogyny. Most families use external rather than internal fertilization, of the oviparous teleosts, most do not provide parental care. Viviparity is relatively rare and is found in about 6% of teleost species, male territoriality preadapts a species for evolving male parental care. There are a few examples of fish that self-fertilise, the mangrove rivulus is an amphibious, simultaneous hermaphrodite, producing both eggs and spawn and having internal fertilisation. This mode of reproduction may be related to the habit of spending long periods out of water in the mangrove forests it inhabits. Males are occasionally produced at temperatures below 19 °C and can fertilise eggs that are spawned by the female. This maintains genetic variability in a species that is otherwise highly inbred, the earliest known fossil actinopterygiian is Andreolepis hedei, dating back 420 million years. Remains have been found in Russia, Sweden, and Estonia, actinopterygians are divided into the subclasses Chondrostei and Neopterygii. The Neopterygii, in turn, are divided into the infraclasses Holostei and Teleostei, during the Mesozoic and Cenozoic the teleosts in particular diversified widely, and as a result, 96% of all known fish species are teleosts. The cladogram shows the groups of actinopterygians and their relationship to the terrestrial vertebrates that evolved from a related group of fish
5.
Cypriniformes
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Cypriniformes is an order of ray-finned fish, including the carps, minnows, loaches and relatives. This order contains 11-12 families, over 400 genera, and more than 4,250 species, with new species being described every few months or so and they are most diverse in southeastern Asia, and are entirely absent from Australia and South America. Their closest living relatives are the Characiformes, the Gymnotiformes and the Siluriformes, like other orders of the Ostariophysi, fishes of cypriniformes possess a Weberian apparatus. They differ from most of their relatives in having only a dorsal fin on their back, further differences are the Cypriniformes unique kinethmoid, a small median bone in the snout, and the lack of teeth in the mouth. Instead, they have convergent structures called pharyngeal teeth in the throat, while other groups of fish, such as cichlids, also possess pharyngeal teeth, the cypriniformes teeth grind against a chewing pad on the base of the skull, instead of an upper pharyngeal jaw. The most notable family placed here is Cyprinidae which make up two-thirds of the orders diversity and this is one of the largest families of fish, and is widely distributed across Africa, Eurasia, and North America. Most species are freshwater inhabitants, but a considerable number are found in brackish water, such as roach. At least one species is found in saltwater, the Pacific redfin, brackish water and marine cyprinids are invariably anadromous, swimming upstream into rivers to spawn. Sometimes separated as family Psilorhynchidae, they seem to be specially-adapted fishes of Cyprinidae, Balitoridae and Gyrinocheilidae are families of mountain stream fishes feeding on algae and small invertebrates. They are found only in tropical and subtropical Asia, while the former are a speciose group, the latter contain only a handful of species. The suckers are found in temperate North America and eastern Asia and these large fishes are similar to carps in appearance and ecology. Members of Cobitidae common across Eurasia and parts of North Africa, historically these included all the forms now placed in the superorder Ostariophysi except the catfish, which were placed in the order Siluriformes. By this definition, the Cypriniformes were paraphyletic, so recently the orders Gonorhynchiformes, Characiformes, the families of Cypriniformes are traditionally divided into two superfamilies. Superfamily Cyprinioidea contains the carps and minnows and, according to some, Catostomoidea is usually treated as a junior synonym of Cobitioidea. But it seems that it could be split off the Catostomidae and Gyrinocheilidae in a distinct superfamily, while the Cyprinioidea seem more primitive than the loach-like forms, they were apparently successful enough never to shift from the original ecological niche of the basal Ostariophysi. Yet, from the ecomorphologically conservative main lineage apparently at least two major radiations branched off and these diversified from the lowlands into torrential river habitats, acquiring similar habitus and adaptations in the process. The mountain carps are highly apomorphic Cyprinidae, perhaps close to true carps, a systematic list, from the most ancient to the most modern lineages, can thus be given as, Superfamily Cyprinoidei Family Cyprinidae Bonaparte,1840 and minnows incl. This is evidenced not only by physiological details, but their great distribution, the earliest that Cypriniformes might have diverged from Characiphysi is thought to be about the Early Triassic, about 250 million years ago
6.
Cyprinidae
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The Cyprinidae are the family of freshwater fishes, collectively called cyprinids, that includes the carps, the true minnows, and their relatives. The family belongs to the ostariophysian order Cypriniformes, of whose genera, the family name is derived from the Ancient Greek kyprînos. Cyprinids are stomachless fish with toothless jaws, even so, food can be effectively chewed by the gill rakers of the specialized last gill bow. These pharyngeal teeth allow the fish to make chewing motions against a chewing plate formed by a process of the skull. The pharyngeal teeth are species-specific and are used by specialists to determine species, strong pharyngeal teeth allow fish such as the common carp and ide to eat hard baits such as snails and bivalves. Hearing is a sense in the cyprinids since they have the Weberian organ. The vertebral processes of the Weberian organ also permit a cyprinid to detect changes in motion of the gas due to atmospheric conditions or depth changes. The cyprinids are considered physostomes because the pneumatic duct is retained in adult stages, Cyprinids are native to North America, Africa, and Eurasia. The largest known cyprinid is the giant barb, which may grow up to 3 m in length and 300 kg in weight, other very large species that can surpass 2 m are the golden mahseer and mangar. The largest North American species is the Colorado pikeminnow, which can reach up to 1.8 m in length, conversely, many species are smaller than 5 cm. The smallest known fish is Paedocypris progenetica, reaching 10.3 mm at the longest, all fish in this family are egg-layers and most do not guard their eggs, however, a few species build nests and/or guard the eggs. The bitterlings of subfamily Acheilognathinae are notable for depositing their eggs in bivalve molluscs, most cyprinids feed mainly on invertebrates and vegetation, probably due to the lack of teeth and stomach, but some species, like the asp, are predators that specialize in fish. Many species, such as the ide, and the common rudd, even small species, such as the moderlieschen, are opportunistic predators that will eat larvae of the common frog in artificial circumstances. For this reason, cyprinids are often introduced as a management tool to control various factors in the environment, such as aquatic vegetation. Cyprinids are highly important food fish, they are fished and farmed across Eurasia, in land-locked countries in particular, cyprinids are often the major species of fish eaten because they make the largest part of biomass in most water types except for fast-flowing rivers. In Eastern Europe, they are prepared with traditional methods. The prevalence of inexpensive frozen fish products made this less important now than it was in earlier times, nonetheless, in certain places, they remain popular for food, as well as recreational fishing, and have been deliberately stocked in ponds and lakes for centuries for this reason. Cyprinids are popular for angling especially for fishing and fishing for common carp because of its size
7.
Borneo
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Borneo is the third-largest island in the world and the largest island in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, the island is politically divided among three countries, Malaysia and Brunei in the north, and Indonesia to the south. Approximately 73% of the island is Indonesian territory, in the north, the East Malaysian states of Sabah and Sarawak make up about 26% of the island. Additionally, the Malaysian federal territory of Labuan is situated on an island just off the coast of Borneo. The sovereign state of Brunei, located on the north coast, antipodal to an area of Amazon rainforest, Borneo is itself home to one of the oldest rainforests in the world, and to Bornean orangutans. The island is known by names, internationally it is known as Borneo, after Brunei. The name Brunei possibly was derived from the Sanskrit word váruṇa, meaning either ocean or the mythological Varuna. Indonesian natives called it Kalimantan, which was derived from the Sanskrit word Kalamanthana, prior to that the island was also known by other names. In 977 Chinese records began to use the term Po-ni to refer to Borneo or Brunei, in 1225 it was also mentioned by the Chinese official Chau Ju-Kua. The Javanese manuscript Nagarakretagama, written by Majapahit court poet Mpu Prapanca in 1365, mentioned the island as Nusa Tanjungnagara, to the west of Borneo are the Malay Peninsula and Sumatra. To the south and east are islands of Indonesia, Java and Sulawesi, to the northeast are the Philippine Islands. With an area of 743,330 square kilometres, it is the third-largest island in the world and its highest point is Mount Kinabalu in Sabah, Malaysia, with an elevation of 4,095 m. The largest river system is the Kapuas in West Kalimantan, with a length of 1,143 km, other major rivers include the Mahakam in East Kalimantan, the Barito in South Kalimantan, and Rajang in Sarawak. Clearwater Cave, for example, has one of the worlds longest underground rivers, deer Cave is home to over three million bats, with guano accumulated to over 100 metres deep. The South China Sea and Gulf of Thailand now submerge the former low-lying areas of the peninsula, the Borneo rainforest is 140 million years old, making it one of the oldest rainforests in the world. There are about 15,000 species of flowering plants with 3,000 species of trees,221 species of mammals and 420 species of resident birds in Borneo. There are about 440 freshwater fish species in Borneo and it is the centre of the evolution and distribution of many endemic species of plants and animals. The Borneo rainforest is one of the few remaining habitats for the endangered Bornean orangutan
8.
Indonesia
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Indonesia, officially the Republic of Indonesia, is a unitary sovereign state and transcontinental country located mainly in Southeast Asia with some territories in Oceania. Situated between the Indian and Pacific oceans, it is the worlds largest island country, with more than seventeen thousand islands. At 1,904,569 square kilometres, Indonesia is the worlds 14th-largest country in terms of area and worlds 7th-largest country in terms of combined sea. It has an population of over 260 million people and is the worlds fourth most populous country. The worlds most populous island, Java, contains more than half of the countrys population, Indonesias republican form of government includes an elected legislature and president. Indonesia has 34 provinces, of which five have Special Administrative status and its capital and countrys most populous city is Jakarta, which is also the most populous city in Southeast Asia and the second in Asia. The country shares land borders with Papua New Guinea, East Timor, other neighbouring countries include Singapore, Vietnam, the Philippines, Australia, Palau, and the Indian territory of the Andaman and Nicobar Islands. Despite its large population and densely populated regions, Indonesia has vast areas of wilderness that support the second highest level of biodiversity. The country has abundant natural resources like oil and natural gas, tin, copper, agriculture mainly produces rice, palm oil, tea, coffee, cacao, medicinal plants, spices and rubber. Indonesias major trading partners are Japan, United States, China, the Indonesian archipelago has been an important region for trade since at least the 7th century, when Srivijaya and then later Majapahit traded with China and India. Local rulers gradually absorbed foreign cultural, religious and political models from the early centuries CE, Indonesian history has been influenced by foreign powers drawn to its natural resources. Indonesia consists of hundreds of native ethnic and linguistic groups. The largest – and politically dominant – ethnic group are the Javanese, a shared identity has developed, defined by a national language, ethnic diversity, religious pluralism within a Muslim-majority population, and a history of colonialism and rebellion against it. Indonesias national motto, Bhinneka Tunggal Ika, articulates the diversity that shapes the country, Indonesias economy is the worlds 16th largest by nominal GDP and the 8th largest by GDP at PPP, the largest in Southeast Asia, and is considered an emerging market and newly industrialised country. Indonesia has been a member of the United Nations since 1950, Indonesia is a member of the G20 major economies and World Trade Organization. The name Indonesia derives from the Greek name of the Indós, the name dates to the 18th century, far predating the formation of independent Indonesia. In 1850, George Windsor Earl, an English ethnologist, proposed the terms Indunesians—and, his preference, in the same publication, one of his students, James Richardson Logan, used Indonesia as a synonym for Indian Archipelago. However, Dutch academics writing in East Indies publications were reluctant to use Indonesia, they preferred Malay Archipelago, the Netherlands East Indies, popularly Indië, the East, and Insulinde
9.
Cambodia
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Cambodia, officially known as the Kingdom of Cambodia, is a country located in the southern portion of the Indochina Peninsula in Southeast Asia. It is 181,035 square kilometres in area, bordered by Thailand to the northwest, Laos to the northeast, Vietnam to the east, Cambodia has a population of over 15 million. The official religion is Theravada Buddhism, practiced by approximately 95 percent of the population, the countrys minority groups include Vietnamese, Chinese, Chams, and 30 hill tribes. The capital and largest city is Phnom Penh, the political, economic, the kingdom is a constitutional monarchy with Norodom Sihamoni, a monarch chosen by the Royal Throne Council, as head of state. The head of government is Hun Sen, who is currently the longest serving leader in South East Asia and has ruled Cambodia for over 25 years. In 802 AD, Jayavarman II declared himself king, uniting the warring Khmer princes of Chenla under the name Kambuja. The Indianized kingdom built monumental temples including Angkor Wat, now a World Heritage Site, after the fall of Angkor to Ayutthaya in the 15th century, a reduced and weakened Cambodia was then ruled as a vassal state by its neighbours. In 1863 Cambodia became a protectorate of France which doubled the size of the country by reclaiming the north, the Vietnam War extended into the country with the US bombing of Cambodia from 1969 until 1973. Following the Cambodian coup of 1970, the king gave his support to his former enemies. Following the 1991 Paris Peace Accords, Cambodia was governed briefly by a United Nations mission, the UN withdrew after holding elections in which around 90 percent of the registered voters cast ballots. The 1997 coup placed power solely in the hands of Prime Minister Hun Sen and the Cambodian Peoples Party, important sociopolitical issues includes widespread poverty, pervasive corruption, lack of political freedoms, low human development, and a high rate of hunger. While per capita income remains low compared to most neighbouring countries, agriculture remains the dominant economic sector, with strong growth in textiles, construction, garments, and tourism leading to increased foreign investment and international trade. Cambodia scored dismally in an annual index ranking the rule of law in 102 countries, placing 99th overall, Cambodia also faces environmental destruction as an imminent problem. The most severe activity in this regard is considered to be the countrywide deforestation, the Kingdom of Cambodia is the official English name of the country. The English Cambodia is an anglicisation of the French Cambodge, which in turn is the French transliteration of the Khmer Kampuchea, Kampuchea is the shortened alternative to the countrys official name in Khmer, Preah Reacheanachak Kampuchea. The Khmer endonym Kampuchea derives from the Sanskrit name Kambujadeśa, composed of देश, desa and कम्बोज, Kambujas, colloquially, Cambodians refer to their country as either Srok Khmer, meaning Khmers Land, or the slightly more formal Prateh Kampuchea, literally Country of Kampuchea. The name Cambodia is used most often in the Western world while Kampuchea is more used in the East. Excavations in its lower layers produced a series of dates as of 6000 BC
10.
PH
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In chemistry, pH is a numeric scale used to specify the acidity or basicity of an aqueous solution. It is approximately the negative of the base 10 logarithm of the concentration, measured in units of moles per liter. More precisely it is the negative of the logarithm to base 10 of the activity of the hydrogen ion, solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. Pure water is neutral, at pH7, being neither an acid nor a base, contrary to popular belief, the pH value can be less than 0 or greater than 14 for very strong acids and bases respectively. The pH scale is traceable to a set of standard solutions whose pH is established by international agreement, the pH of aqueous solutions can be measured with a glass electrode and a pH meter, or an indicator. In the first papers, the notation had the H as a subscript to the p, as so. The exact meaning of the p in pH is disputed, but according to the Carlsberg Foundation and it has also been suggested that the p stands for the German Potenz, others refer to French puissance. Another suggestion is that the p stands for the Latin terms pondus hydrogenii, potentia hydrogenii and it is also suggested that Sørensen used the letters p and q simply to label the test solution and the reference solution. Currently in chemistry, the p stands for decimal cologarithm of, PH is defined as the decimal logarithm of the reciprocal of the hydrogen ion activity, aH+, in a solution. P H = − log 10 = log 10 For example and this definition was adopted because ion-selective electrodes, which are used to measure pH, respond to activity. For H+ number of electrons transferred is one and it follows that electrode potential is proportional to pH when pH is defined in terms of activity. The reference electrode may be a silver chloride electrode or a calomel electrode, the hydrogen-ion selective electrode is a standard hydrogen electrode. Reference electrode | concentrated solution of KCl || test solution | H2 | Pt Firstly, the cell is filled with a solution of hydrogen ion activity. Then the emf, EX, of the cell containing the solution of unknown pH is measured. PH = pH + E S − E X z The difference between the two measured emf values is proportional to pH and this method of calibration avoids the need to know the standard electrode potential. The proportionality constant, 1/z is ideally equal to 12.303 R T / F the Nernstian slope, to apply this process in practice, a glass electrode is used rather than the cumbersome hydrogen electrode. A combined glass electrode has a reference electrode. It is calibrated against buffer solutions of hydrogen ion activity
11.
Melanism
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Melanism is a development of the dark-colored pigment melanin in the skin or its appendages and is the opposite of albinism. Historically, it was also the term for black jaundice. The word melanism is derived from the Greek, μελανός, a deficiency in or total absence of melanin pigments is called amelanism. The morbid deposition of black matter, often of a malignant character causing pigmented tumors, is called melanosis, for a description of melanin-related disorders, see melanin, melanosis coli and ocular melanosis. Melanism related to the process of adaptation is called adaptive, most commonly, dark individuals become fitter to survive and reproduce in their environment as they are better camouflaged. This makes some species less conspicuous to predators, while others, such as black panthers, typically, adaptive melanism is heritable, A dominant gene, which is entirely or nearly entirely expressed in the phenotype, is responsible for the excessive amount of melanin. Adaptive melanism has been shown to occur in a variety of animals, including such as squirrels, many felines and canids. Industrial melanism is an effect of urban pollution prominent in species of arthropods. It is the phenomenon of an organism evolving dark pigmentation when exposed to an environment polluted by dark soot deposit, in this type of industrial melanism, the darker pigmented individuals develop a higher fitness and are favored by natural selection. This change in favoritism as a result of modification in selection pressure is one of the cases of Darwinian evolution. The most common case of this adaptation is found in the arthropod order Lepidoptera and this order of insects encompasses all insects with microscopic scales on their wings, such as moths and butterflies. Originally, peppered moths lived where light-colored lichens covered the trees where they would rest, to camouflage with the tree, they originated with a light-colored pigment that helped them to avoid predators by not being a visual distraction. Lichens are great bio-indicators of air-pollution, sulfur dioxide present in the atmosphere reduces the amount of lichen covering the surrounding trees. This reversal of survivability made the gene contributing to melanic forms of the more desirable. The melanic phenotype of the Biston betularia has been calculated to give an advantage as great as 30 per cent. As generations went on, eventually the population of peppered moths transformed from the majority being light-colored moths to the majority being dark-colored moths, melanic Biston betularia have also been widely observed in North America. In 1959, 90% of the Biston betularia in Michigan and Pennsylvania had the melanic phenotype, by 2001, melanism dropped to 6% of the population, following clean air legislation. In each of these situations, the form of the organism was found in an environment in correlation to higher amounts of industrial pollution found in the area
12.
Shoaling and schooling
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In biology, any group of fish that stay together for social reasons are shoaling, and if the group is swimming in the same direction in a coordinated manner, they are schooling. In common usage, the terms are used rather loosely. About one quarter of fish species shoal all their lives, Fish derive many benefits from shoaling behaviour including defence against predators, enhanced foraging success, and higher success in finding a mate. It is also likely that fish benefit from shoal membership through increased hydrodynamic efficiency, Fish use many traits to choose shoalmates. Generally they prefer larger shoals, shoalmates of their own species, shoalmates similar in size and appearance to themselves, healthy fish, the oddity effect posits that any shoal member that stands out in appearance will be preferentially targeted by predators. This may explain why fish prefer to shoal with individuals that resemble themselves, the oddity effect would thus tend to homogenize shoals. An aggregation of fish is the term for any collection of fish that have gathered together in some locality. Fish aggregations can be structured or unstructured, an unstructured aggregation might be a group of mixed species and sizes that have gathered randomly near some local resource, such as food or nesting sites. If, in addition, the aggregation comes together in an interactive, social way, shoaling groups can include fish of disparate sizes and can including mixed-species subgroups. If the shoal becomes more organised, with the fish synchronising their swimming so they all move at the same speed and in the same direction. Schooling fish are usually of the species and the same age/size. Fish schools move with the individual members precisely spaced from each other, the schools undertake complicated manoeuvres, as though the schools have minds of their own. The intricacies of schooling are far from understood, especially the swimming and feeding energetics. Many hypotheses to explain the function of schooling have been suggested, such as orientation, synchronized hunting, predator confusion. Schooling also has disadvantages, such as excretion buildup in the media and oxygen. The way the array in the school probably gives energy saving advantages. Fish can be obligate or facultative shoalers, obligate shoalers, such as tunas, herrings and anchovy, spend all of their time shoaling or schooling, and become agitated if separated from the group. Facultative shoalers, such as Atlantic cod, saiths and some carangids, shoal only some of the time, shoaling fish can shift into a disciplined and coordinated school, then shift back to an amorphous shoal within seconds
