"Melanism Melanism is a development of the dark-colored pigment melanin in the skin or its appendages and is the opposite of albinism. The word ""melanism"" is derived from the (""black pigment""). Pseudo-melanism, also called abundism, is another variant of pigmentation, characterized by dark spots or enlarged stripes, which cover a large part of the body of the animal, making it appear melanistic. 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 and"
"Albinism Albinism is the ""congenital absence of any pigmentation or coloration in a person, animal or plant, resulting in white hair, feathers, scales and skin and pink eyes in mammals, birds, reptiles, amphibians and fish and other small invertebrates as well."" Varied use and interpretation of the terms mean that written reports of albinistic animals can be difficult to verify. Albinism can reduce the survivability of an animal; for example, it has been suggested that albino alligators have an average survival span of only 24 hours due to the lack of protection from UV and their lack of camouflage to"
"invertebrates, nor does it include plants. Furthermore, it could be interpreted that ""...absence of pigment..."" does not include an absence of structural colours. The lack of clarity about the term is furthered when the name of an animal includes the term ""albino"" although the animals (clearly) do not have the condition. For example, the albino gaur has this name because it is ash-grey whereas other gaur are almost black, and the American albino horse is a chestnut with a dilution gene. A clear definition appears to be – ""Congenital absence of any pigmentation or coloration in a person, animal, or"
"Hypopigmentation Hypopigmentation is characterized specifically as an area of skin becoming lighter than the baseline skin color, but not completely devoid of pigment. This is not to be confused with depigmentation, which is characterized as the absence of all pigment. It is caused by melanocyte or melanin depletion, or a decrease in the amino acid tyrosine, which is used by melanocytes to make melanin. Some common genetic causes include mutations in the tyrosinase gene or OCA2 gene. As melanin pigments tend to be in the skin, eye, and hair, these are the commonly affected areas in those with hypopigmentation. Hypopigmentation"
"Amelanism Amelanism (also known as amelanosis) is a pigmentation abnormality characterized by the lack of pigments called melanins, commonly associated with a genetic loss of tyrosinase function. Amelanism can affect fish, amphibians, reptiles, birds, and mammals including humans. The appearance of an amelanistic animal depends on the remaining non-melanin pigments. The opposite of amelanism is melanism, a higher percentage of melanin. A similar condition, albinism, is a hereditary condition characterised in animals by the absence of pigment in the eyes, skin, hair, scales, feathers or cuticle. This results in an all white animal, usually with pink or red eyes. Melanin"
"or no pigment in the stroma, but retain pigment in the iris pigment epithelium. If pigment is missing from both the stroma and the iris pigment epithelium, the only pigment in the eye is the hemoglobin in blood vessels. This accounts for the reddish appearance of eyes in some types of albinism. In research mammals, such as mice, albinism is more strictly defined. Albino mice occur due to a recessive mutation of the ""C"" gene. No such mutation exists in horses. Albino mice lack pigment, but ""...the inability of albino animals to produce pigment stems not from an absence of"
"Leucism Leucism () is a condition in which there is partial loss of pigmentation in an animal resulting in white, pale, or patchy coloration of the skin, hair, feathers, scales or cuticle, but not the eyes. It is occasionally spelled ""leukism"". Unlike albinism, it is caused by a reduction in multiple types of pigment, not just melanin. Leucism is a general term for the phenotype resulting from defects in pigment cell differentiation and/or migration from the neural crest to skin, hair, or feathers during development. This results in either the entire surface (if all pigment cells fail to develop) or"
"Light skin Light skin is a naturally occurring human skin color, which has little eumelanin pigmentation and which has been adapted to environments of low UV radiation. Light skin is most commonly found amongst the native populations of Europe and Northeast Asia as measured through skin reflectance. People with light skin pigmentation are often referred to as ""white"" or ""fair"", although these usages can be ambiguous in some countries where they are used to refer specifically to certain ethnic groups or populations. As populations migrated away from the tropics between 125,000 and 65,000 years ago into areas of low UV"
"pigmentation"" Other definitions of albinism encompass most of the major animal taxa, but ignore the several other pigments that non-mammalian animals have and also structural colouration. For example, ""Absence of the pigment melanin in the eyes, skin, hair, scales, or feathers."" refers only to the pigment melanin. Because of the various uses of different terms applied to colouration, some authors have indicated that the colour of the eyes is the defining characteristic of albinism, e.g. ""This leads to a good diagnostic feature with which to distinguish leucistic and albino individuals – the colour of the eye."" The term ""partial albino"""
"Skin with little or no melanin is almost white. Other factors influence skin color in a lesser degree, including the amount of blood in blood vessels (because of the color of blood), skin thickness and content of carotenoids in skin. Melanin in synthesized in melanosomes which are organelles produced in melanocytes. Melanocytes are cells dedicated to this function that are present in the skin, hair follicles, and other structures of the body. The synthesis of melanin (also called ""melanogenesis"" and ""melanization"") involves a chain of enzyme-catalyzed chemical reactions and non-enzyme-catalyzed reactions. The main precursor to melanin is -tyrosine. The first"
"and indigenous populations are all light-skinned. Light skin Light skin is a naturally occurring human skin color, which has little eumelanin pigmentation and which has been adapted to environments of low UV radiation. Light skin is most commonly found amongst the native populations of Europe and Northeast Asia as measured through skin reflectance. People with light skin pigmentation are often referred to as ""white"" or ""fair"", although these usages can be ambiguous in some countries where they are used to refer specifically to certain ethnic groups or populations. As populations migrated away from the tropics between 125,000 and 65,000 years"
"with abnormalities in the migration of melanoblasts are known collectively as piebaldism. Pigment cells of the iris pigment epithelium have a separate embryological origin. Piebaldism and amelanism are distinct conditions. The only pigments that mammals produce are melanins. For a mammal to be unable to chemically manufacture melanin renders it completely pigmentless. This condition is more commonly called albinism. Amelanistic mammals have white hair, pink skin, and eyes that have a pink, red, or violet appearance. Reddish eyes are due to the lack of pigment in the iris pigment epithelium. When the stroma is unpigmented but the iris pigment epithelium"
"Biological pigment Biological pigments, also known simply as pigments or biochromes, are substances produced by living organisms that have a color resulting from selective color absorption. Biological pigments include plant pigments and flower pigments. Many biological structures, such as skin, eyes, feathers, fur and hair contain pigments such as melanin in specialized cells called chromatophores. Pigment color differs from structural color in that it is the same for all viewing angles, whereas structural color is the result of selective reflection or iridescence, usually because of multilayer structures. For example, butterfly wings typically contain structural color, although many butterflies have cells"
"Nudity Nudity, or nakedness, is the state of wearing no clothing. The deliberate and conscious wearing of clothing is a behavioural adaptation, which among all known extant and extinct animals is a uniquely human characteristic arising from functional needs such as protection from the elements. Protection from the elements includes the sun (for depigmented human populations) and cold temperatures after the loss of body hair and the migration of humans to colder regions (around 100,000 years ago) in which they had not evolved and thus lacked the necessary physical adaptations. According to some researchers, wearing clothes may predate early human"
"and maps difficult to read. Less common forms of dichromacy include protoanopia (lack of L-cones), and tritanopia (lack of S-cones). If a person lacks two types of photopigments, they are considered monochromats. People lacking the three types of photopigments are said to have complete color blindness or achromatopsia. Color blindness can also result from damages to the visual cortex in the brain. Experiments using a variety of mammals (including primates) demonstrated that it is possible to confer color vision to animals by introducing an opsin gene that the animal previously lacked. Using a replication-defective recombinant adeno-associated virus (rAAV) as a"
"the difference between lack of phaeomelanin and abundance of eumelanin is one of words. Some agouti alleles in mice are associated with health defects, but this is not the case in dogs, cats, or horses. Amelanism Amelanism (also known as amelanosis) is a pigmentation abnormality characterized by the lack of pigments called melanins, commonly associated with a genetic loss of tyrosinase function. Amelanism can affect fish, amphibians, reptiles, birds, and mammals including humans. The appearance of an amelanistic animal depends on the remaining non-melanin pigments. The opposite of amelanism is melanism, a higher percentage of melanin. A similar condition, albinism,"
"their albino squirrel as the university's secondary mascot. The University of Louisville in Kentucky also has a documented population of albino squirrels. Albino animals are often kept as pets, for example, African clawed frog, guinea pigs and peacocks. Albinism Albinism is the ""congenital absence of any pigmentation or coloration in a person, animal or plant, resulting in white hair, feathers, scales and skin and pink eyes in mammals, birds, reptiles, amphibians and fish and other small invertebrates as well."" Varied use and interpretation of the terms mean that written reports of albinistic animals can be difficult to verify. Albinism can"
"Leucoplast Leucoplasts (λευκός leukós ""white"", πλαστός plastós ""formed, molded"") are a category of plastid and as such are organelles found in plant cells. They are non-pigmented, in contrast to other plastids such as the chloroplast. Lacking photosynthetic pigments, leucoplasts are not green and are located in non-photosynthetic tissues of plants, such as roots, bulbs and seeds. They may be specialized for bulk storage of starch, lipid or protein and are then known as amyloplasts, elaioplasts, or proteinoplasts (also called aleuroplasts) respectively. However, in many cell types, leucoplasts do not have a major storage function and are present to provide a"
"Gelatin Gelatin or gelatine (from meaning ""stiff"" or ""frozen"") is a translucent, colorless, brittle (when dry), flavorless food ingredient that is derived from collagen obtained from various animal body parts. It is also referred to as hydrolyzed collagen, collagen hydrolysate, gelatine hydrolysate, hydrolyzed gelatine, and collagen peptides. It is commonly used as a gelling agent in food, medications, drug and vitamin capsules, photographic films and papers, and cosmetics. Substances containing gelatin or functioning in a similar way are called ""gelatinous"". Gelatin is an irreversibly hydrolyzed form of collagen, wherein the hydrolysis results in the reduction of protein fibrils into smaller"
"melanocytes...but from a deficiency and/or alteration of the structure of tyrosinase in melanocytes which are otherwise normal."" This definition of albinism in mice - the inability to make tyrosinase - is extended to other mammals. While mammals derive their pigments only from melanins, fish, reptiles and birds rely on a number of pigments apart from melanins: carotenoids, porphyrins, psittacofulvins, pterins, etc. Most commonly, reptiles with a condition homologous to human OCA1A retain their reddish and orangish hues. As a result, birds and reptiles without the ability to manufacture tyrosinase are more accurately described as ""amelanistic."" Horses do not have non-melanin"
"Nevus sebaceous Nevus sebaceus or sebaceous nevus (the first term is its Latin name, the second term is its name in English; also known as an ""organoid nevus"" and ""nevus sebaceus of Jadassohn"") is a congenital, hairless plaque that typically occurs on the face or scalp. Such nevi are present at birth, or early childhood, affecting males and females of all races equally. The condition is named for an overgrowth of sebaceous glands in the area of the nevus. Skin growths such as benign tumors and basal cell carcinoma can arise in sebaceous nevi, usually in adulthood. Rarely, sebaceous nevi"
"and ""EDNRB. The terms ""leucistic"" and ""leucism"" are derived from medical terminology (""leuc-"" + ""-ism""). The stem ""leuc-"" is the Latin variant of ""leuk-"" from the Greek ""leukos"" meaning ""white"" (see Stedman’s, Dorland’s or Taber’s medical dictionaries). Leucism has been noted in a number of animal species, including: Leucism Leucism () is a condition in which there is partial loss of pigmentation in an animal resulting in white, pale, or patchy coloration of the skin, hair, feathers, scales or cuticle, but not the eyes. It is occasionally spelled ""leukism"". Unlike albinism, it is caused by a reduction in multiple types"
"plant, resulting in white hair and pink eyes in mammals."" Whilst this does not state specifically that non-mammalian albino animals (or plants) are white, this can be inferred from ""...absence of any pigmentation or coloration..."" Due to the varied use and interpretation of the term ""albino"", written reports of albinistic organisms can often not be verified. Melanin is an organic pigment that produces most of the colour seen in mammals. Depending on how it is created, melanin comes in two colour ranges, eumelanin (producing dark browns and blacks) and pheomelanin (producing light reddish tans and blondes). The dark and light"
"(pigment organs) common to most cephalopods are poorly developed in the vampire squid. Although the animal is, therefore, incapable of changing its skin colour in the dramatic fashion of shallow-dwelling cephalopods, such ability would not be useful at the lightless depths where it lives. The vampire squid is an extreme example of a deep sea cephalopod, thought to reside at aphotic (lightless) depths from or more. Within this region of the world's oceans is a discrete habitat known as the oxygen minimum zone. Within the zone, the saturation of oxygen is too low to support aerobic metabolism in most complex"
"no visible light reaches the eye. Pigments or dyes that absorb light rather than reflect it back to the eye ""look black"". A black pigment can, however, result from a ""combination"" of several pigments that collectively absorb all colors. If appropriate proportions of three primary pigments are mixed, the result reflects so little light as to be called ""black"". This provides two superficially opposite but actually complementary descriptions of black. Black is the absorption of all colors of light, or an exhaustive combination of multiple colors of pigment. See also primary colors. In physics, a black body is a perfect"
"the hippopotamus has very little hair. The skin is thick, providing it great protection against conspecifics and predators. By contrast, its subcutaneous fat layer is thin. The animals' upper parts are purplish-gray to blue-black, while the under parts and areas around the eyes and ears can be brownish-pink. Their skin secretes a natural sunscreen substance which is red-coloured. The secretion is sometimes referred to as ""blood sweat"", but is neither blood nor sweat. This secretion is initially colourless and turns red-orange within minutes, eventually becoming brown. Two distinct pigments have been identified in the secretions, one red (hipposudoric acid) and"
"hemoglobin. Mature red blood cell without a nucleus, can properly deliver oxygen. Chromatin diminution is a process of partial elimination of chromatin genetic material from genome of prospective somatic cells. This process was found to occur during the early developmental stage in three groups: nematodes, copepods, and hagfish One of the first studies regarding somatic genome processing was observed by Boveri large-scale chromatin elimination in parasitic nematode ""Parascaris univalens"". During chromatin diminution, somatic chromosomes becomes fragmented with new telomeres added in many different places and devoid of heterochromatin so it differs from germline cell in respect of structure and genetic"
"the circulatory fluid is commonly referred to as haemolymph, rather than blood. The majority of gastropods have haemolymph containing the respiratory pigment haemocyanin. This is a copper-containing protein that helps to carry oxygen, and gives the haemolymph a pale blue colour. In the freshwater Planorbid snails, however, the haemocyanin is replaced by haemoglobin, and thus their haemolymph is red rather than blue. Some gastropods, such as the sea hare ""Aplysia"", appear to lack respiratory pigments altogether. Regardless of whether they employ haemocyanin or haemoglobin, the pigments are dissolved directly in the serum, with no equivalent of the red blood cells"
"animals have pigments other than melanin, and some also have structural colours. Some definitions of albinism, whilst taking most taxa into account, ignore others. So, ""a person or animal with very pale skin, white hair or fur, and pink eyes caused by a medical condition that they were born with"" and ""a person or animal with white skin and hair and pink eyes"" do not include feathers, scales or cuticles of birds, fish and invertebrates. Nor do they include plants. Some definitions are too broad to be of much use, e.g. ""an animal or plant with a marked deficiency in"
"Lentigo A lentigo () (plural lentigines, ) is a small pigmented spot on the skin with a clearly defined edge, surrounded by normal-appearing skin. It is a harmless (benign) hyperplasia of melanocytes which is linear in its spread. This means the hyperplasia of melanocytes is restricted to the cell layer directly above the basement membrane of the epidermis where melanocytes normally reside. This is in contrast to the ""nests"" of multi-layer melanocytes found in moles (melanocytic nevi). Because of this characteristic feature, the adjective ""lentiginous"" is used to describe other skin lesions that similarly proliferate linearly within the basal cell"
"This process, known as ""physiological colour change"", is most widely studied in melanophores, since melanin is the darkest and most visible pigment. In most species with a relatively thin dermis, the dermal melanophores tend to be flat and cover a large surface area. However, in animals with thick dermal layers, such as adult reptiles, dermal melanophores often form three-dimensional units with other chromatophores. These dermal chromatophore units (DCU) consist of an uppermost xanthophore or erythrophore layer, then an iridophore layer, and finally a basket-like melanophore layer with processes covering the iridophores. Both types of melanophore are important in physiological colour"
"pigment, giving white hair and no pigmented skin: albinism. Mutations are random changes in genes creating new alleles, which in turn produce new traits, which could help, harm, or have no new effect on the individual's likelihood of survival; thus, mutations are the basis for evolution. Genes are pieces of DNA that contain information for synthesis of ribonucleic acids (RNAs) or polypeptides. Genes are inherited as units, with two parents dividing out copies of their genes to their offspring. This process can be compared with mixing two hands of cards, shuffling them, and then dealing them out again. Humans have"
"C Ward & N H Altman, Spontaneous Animal Models of Human Disease, pp 11–16, Academic Press, New York. Piebald A piebald or pied animal is one that has a pattern of pigmented spots on an unpigmented (white) background of hair, feathers or scales. The spots are pigmented in shades of black and/or yellow as determined by the genotype controlling the color of the animal. The animal's skin underneath its coat may or may not be pigmented under the spots but the skin in the white background is not pigmented. Location of the pigmented spots is dependent on the migration of"