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Fur is used in reference to the hair of animals, usually mammals, particularly those with extensive body hair coverage. The term "pelage" (French, from Middle French, from ''poil'' hair, from Old French ''peilss'', from Latin ''pilus''; first known use in English c. 1828.〔(【引用サイトリンク】title=Pelage )〕) is sometimes used to refer to the body hair of an animal as a complete coat. ''Fur'' is also used to refer to animal pelts which have been processed into leather with the hair still attached. The words ''fur'' or ''furry'' are also used, more casually, to refer to hair-like growths or formations, particularly when the subject being referred to exhibits a dense coat of fine, soft "hairs." Animal ''fur'', if layered, rather than grown as a single coat, may consist of short down hairs, long guard hairs, and, in some cases, medium awn hairs. Mammals with reduced amounts of fur are often called "naked", such as naked mole-rat and naked dogs. An animal with commercially valuable fur is known within the fur industry as a furbearer. The use of fur as clothing and/or decoration is considered controversial by some people: most animal welfare advocates object to the trapping and killing of wildlife, and to the confinement and killing of animals on fur farms. Fur has been a major challenge for 3D computer graphics artists due to its visual complexity and physical properties. The first movie which made extensive use of CGI fur was Pixar's 2001 film ''Monsters, Inc.'' ==Composition== Fur usually consists of two main layers: *Down hair (known also as undercoat or ground hair) — the bottom layer consisting of wool hairs, usually wavy or curly without straight portions or sharp points; down hairs tend to be shorter, flat, curly, and more numerous than the top layer. Its principal function is thermoregulation; it maintains a layer of dry air next to the skin and repels water, thus providing thermal insulation. *Guard hair — the top layer consisting of longer, generally coarser, nearly straight shafts of hair that protrude through the down hair layer. The distal ends of the guard hairs provide the externally visible layer of the coat of most mammals with well-developed fur. This layer of the coat displays the most marked pigmentation and gloss, including coat patterns adapted to display or camouflage. It is also adapted to shedding water and blocking sunlight, protecting the undercoat and skin from external factors such as rain and ultraviolet radiation. Many animals, such as domestic cats, erect their guard hairs as part of their threat display when agitated. Mammals with well-developed down and guard hairs also usually have large numbers of awn hairs. These begin their growth much as guard hairs do, but change their mode of growth, usually when less than half the length of the hair has emerged. This portion of the hair is called awn. The rest of the growth is thin and wavy, much like down hair. In many species of mammals, the awn hairs comprise the bulk of the visible coat. The proximal part of the awn hair shares the function of the down hairs, whereas the distal part aids the water-shedding function of the guard hairs, though their thin basal portion prevents their being erected like true guard hairs. The modern fur arrangement is known to have occurred as far back as docodonts and eutriconodonts, with ''Castorocauda'' and ''Spinolestes'' preserving compound follicles with guard hair and underfur. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「fur」の詳細全文を読む スポンサード リンク
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