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Trichromat
Trichromacy or trichromatism is the possession of three independent channels for conveying color information, derived from the three different types of cone cells in the eye. Organisms with trichromacy are called trichromats. The normal explanation of trichromacy is that the organism's retina contains three types of color receptors (called cone cells in vertebrates) with different absorption spectra. In actuality, the number of such receptor types may be greater than three, since different types may be active at different light intensities. In vertebrates with three types of cone cells, at low light intensities the rod cells may contribute to color vision. Humans and other animals that are trichromats Humans and some other mammals have evolved trichromacy based partly on pigments inherited from early vertebrates. In fish and birds, for example, four pigments are used for vision. These extra cone receptor visual pigments detect energy of other wavelengths, sometimes includi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New World Monkey
New World monkeys are the five families of primates that are found in the tropical regions of Mexico, Central and South America: Callitrichidae, Cebidae, Aotidae, Pitheciidae, and Atelidae. The five families are ranked together as the Ceboidea (), the only extant superfamily in the parvorder Platyrrhini (). Platyrrhini is derived from the Greek for "broad nosed", and their noses are flatter than those of other simians, with sideways-facing nostrils. Monkeys in the family Atelidae, such as the spider monkey, are the only primates to have prehensile tails. New World monkeys' closest relatives are the other simians, the Catarrhini ("down-nosed"), comprising Old World monkeys and apes. New World monkeys descend from African simians that colonized South America, a line that split off about 40 million years ago. Evolutionary history About 40 million years ago, the Simiiformes infraorder split into the parvorders Platyrrhini (New World monkeys) and Catarrhini (apes and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Howler Monkey
Howler monkeys (genus ''Alouatta'', monotypic in subfamily Alouattinae) are the most widespread primate genus in the Neotropical realm, Neotropics and are among the largest of the New World monkey, platyrrhines along with the muriquis (''Brachyteles''), the spider monkeys (''Ateles'') and woolly monkeys (''Lagotrix''). The monkeys are native to South America, South and Central American forests. They are famous for their Howling, howls, which can be heard from a distance through dense rain forest. Fifteen species are recognized. Previously classified in the Family (biology), family Cebidae, they are now placed in the family Atelidae. They are primarily folivores but also significant frugivores, acting as seed dispersal agents through their digestive system and their Animal locomotion, locomotion. Threats include human predation, habitat destruction, Wildlife trade, illegal wildlife trade, and Captivity (animal), capture for pets or zoo animals. Classification Anatomy and physiol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Color
Color (or colour in English in the Commonwealth of Nations, Commonwealth English; American and British English spelling differences#-our, -or, see spelling differences) is the visual perception based on the electromagnetic spectrum. Though color is not an inherent property of matter, color perception is related to an object's light absorption, emission spectra, emission, Reflection (physics), reflection and Transmittance, transmission. For most humans, colors are perceived in the visible light spectrum with three types of cone cells (trichromacy). Other animals may have a different number of cone cell types or have eyes sensitive to different wavelengths, such as bees that can distinguish ultraviolet, and thus have a different color sensitivity range. Animal perception of color originates from different light wavelength or spectral sensitivity in cone cell types, which is then processed by the brain. Colors have perceived properties such as hue, colorfulness (saturation), and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Color Vision
Color vision, a feature of visual perception, is an ability to perceive differences between light composed of different frequencies independently of light intensity. Color perception is a part of the larger visual system and is mediated by a complex process between neurons that begins with differential stimulation of different types of photoreceptors by light entering the eye. Those photoreceptors then emit outputs that are propagated through many layers of neurons ultimately leading to higher cognitive functions in the brain. Color vision is found in many animals and is mediated by similar underlying mechanisms with common types of biological molecules and a complex history of the evolution of color vision within different animal taxa. In primates, color vision may have evolved under selective pressure for a variety of visual tasks including the foraging for nutritious young leaves, ripe fruit, and flowers, as well as detecting predator camouflage and emotional states in othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrachromacy
Tetrachromacy (from Ancient Greek ''tetra'', meaning "four" and ''chroma'', meaning "color") is the condition of possessing four independent channels for conveying color information, or possessing four types of cone cell in the eye. Organisms with tetrachromacy are called tetrachromats. In tetrachromatic organisms, the sensory color space is four-dimensional, meaning that matching the sensory effect of arbitrarily chosen spectra of light within their visible spectrum requires mixtures of at least four primary colors. Tetrachromacy is demonstrated among several species of birds, fishes, and reptiles. The common ancestor of all vertebrates was a tetrachromat, but a common ancestor of mammals lost two of its four kinds of cone cell, evolving dichromacy, a loss ascribed to the conjectured nocturnal bottleneck. Some primates then later evolved a third cone. Physiology The normal explanation of tetrachromacy is that the organism's retina contains four types of higher-intensity lig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marsupial
Marsupials are a diverse group of mammals belonging to the infraclass Marsupialia. They are natively found in Australasia, Wallacea, and the Americas. One of marsupials' unique features is their reproductive strategy: the young are born in a relatively undeveloped state and then nurtured within a pouch on their mother's abdomen. Extant marsupials encompass many species, including Kangaroo, kangaroos, Koala, koalas, Opossum, opossums, Phalangeriformes, possums, Tasmanian devil, Tasmanian devils, Wombat, wombats, Wallaby, wallabies, and Bandicoot, bandicoots. Marsupials constitute a clade stemming from the last common ancestor of extant Metatheria, which encompasses all mammals more closely related to marsupials than to Placentalia, placentals. The evolutionary split between placentals and marsupials occurred 125-160 million years ago, in the Middle Jurassic-Early Cretaceous period. Presently, close to 70% of the 334 extant marsupial species are concentrated on the Australian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Australia
Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller islands. It has a total area of , making it the list of countries and dependencies by area, sixth-largest country in the world and the largest in Oceania. Australia is the world's flattest and driest inhabited continent. It is a megadiverse countries, megadiverse country, and its size gives it a wide variety of landscapes and Climate of Australia, climates including deserts of Australia, deserts in the Outback, interior and forests of Australia, tropical rainforests along the Eastern states of Australia, coast. The ancestors of Aboriginal Australians began arriving from south-east Asia 50,000 to 65,000 years ago, during the Last Glacial Period, last glacial period. By the time of British settlement, Aboriginal Australians spoke 250 distinct l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Honey Possum
The honey possum or noolbenger (''Tarsipes rostratus''), is a tiny species of marsupial that feeds on the nectar and pollen of a diverse range of flowering plants. Found only in southwest Australia, it is an important pollinator for such plants as '' Banksia attenuata'', '' Banksia coccinea'' and ''Adenanthos cuneatus''. Taxonomy The first description of the diprotodont species was published by Paul Gervais and Jules Verreaux on 3 March 1842, referring to a specimen collected by Verreaux. The lectotype nominated for this species, held in the collection at National Museum of Natural History, France, was collected the Swan River Colony. A description of a second species ''Tarsipes spenserae'', published five days later by John Edward Gray and current until the 1970s, was thought to have been published earlier by T. S. Palmer in 1904 and displaced the usage of ''T. rostratus''. A review by Mahoney in 1984 again reduced ''T. spenserae'' to a synonym for the species, as was t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fat-tailed Dunnart
The fat-tailed dunnart (''Sminthopsis crassicaudata'') is a species of mouse-like marsupial of the Dasyuridae, the family that includes the little red kaluta, quolls, and the Tasmanian devil. Description It has an average body length of with a tail of . Its ear length is . One of the smallest carnivorous marsupials, it varies in weight between . The tail becomes fat a few millimeters from the proximal end and remains so right up to the tip. The dunnart has trichromat vision, similar to that of some other marsupials as well as primates, but unlike most mammals, which have dichromat vision. Distribution and habitat The range of ''S. crassicaudata'' in Australia is in diverse habitats except for the Kimberley region of Western Australia and the northern Northern Territory like Arnhem Land and Kakadu National Park, but avoids the Wannon and Mallee scrub habitats in Victoria. In the northeast of Victoria, the species can also be found in grassy woodlands and samphire s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tricolour Television Close Up
A triband is a vexillological style which consists of three stripes arranged to form a flag. These stripes may be two or three colours, and may be charged with an emblem in the middle stripe. Not all tribands are tricolour flags, which requires three unique colours. Design Outside of the name, which requires three bands of colour, there are no other requirements for what a triband must look like, so there are many flags that look very different from each other but are all considered tribands. Some triband flags (e.g. those of Germany, Russia and the Netherlands) have their stripes positioned horizontally, while others (e.g. that of Italy) position the stripes vertically. Often the stripes on a triband are of equal length and width, though this is not always the case, as can be seen in the flags of Colombia and Canada. Symbols on tribands may be seals, such as on the Belizean flag, or any manner of emblems of significance to the area the flag represents, such as in the flags o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heredity
Heredity, also called inheritance or biological inheritance, is the passing on of traits from parents to their offspring; either through asexual reproduction or sexual reproduction, the offspring cells or organisms acquire the genetic information of their parents. Through heredity, variations between individuals can accumulate and cause species to evolve by natural selection. The study of heredity in biology is genetics. Overview In humans, eye color is an example of an inherited characteristic: an individual might inherit the "brown-eye trait" from one of the parents. Inherited traits are controlled by genes and the complete set of genes within an organism's genome is called its genotype. The complete set of observable traits of the structure and behavior of an organism is called its phenotype. These traits arise from the interaction of the organism's genotype with the environment. As a result, many aspects of an organism's phenotype are not inherited. For example, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolution
Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. The process of evolution has given rise to biodiversity at every level of biological organisation. The scientific theory of evolution by natural selection was conceived independently by two British naturalists, Charles Darwin and Alfred Russel Wallace, in the mid-19th century as an explanation for why organisms are adapted to their physical and biological environments. The theory was first set out in detail in Darwin's book ''On the Origin of Species''. Evolution by natural selection is established by observable facts about living organisms: (1) more offspring are often produced than can possibly survive; (2) phenotypic variatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
