Wikipedia

Fur

(Redirected fromPelt)
"Furs" and "Pelt" redirect here. For other uses, seeFur (disambiguation),Furs (disambiguation),andPelt (disambiguation).

Furis a thick growth ofhairthat covers the skin of almost allmammals.It consists of a combination of oilyguard hairon top and thickunderfurbeneath. The guard hair keeps moisture from reaching the skin; the underfur acts as aninsulatingblanket that keeps the animal warm.[1]

Like many mammals,grizzly bearsare covered in thick fur.

The fur of mammals has many uses: protection, sensory purposes, waterproofing, and camouflaging, with the primary usage being thermoregulation.[2]The types of hair include[3]: 99 

  • definitive,which may beshedafter reaching a certain length;
  • vibrissae,which are sensory hairs and are most commonly whiskers;
  • pelage,which consists of guard hairs, under-fur, andawn hair;
  • spines,which are a type of stiff guard hair used for defense in, for example,porcupines;
  • bristles,which are long hairs usually used in visual signals, such as themaneof a lion;
  • velli,often called "down fur", which insulates newborn mammals; and
  • wool,which is long, soft, and often curly.

Hair length is negligible in thermoregulation, as some tropical mammals, such as sloths, have the same fur length as some arctic mammals but with less insulation; and, conversely, other tropical mammals with short hair have the same insulating value as arctic mammals. The denseness of fur can increase an animal's insulation value, and arctic mammals especially have dense fur; for example, themuskoxhas guard hairs measuring 30 cm (12 in) as well as a dense underfur, which forms an airtight coat, allowing them to survive in temperatures of −40 °C (−40 °F).[3]: 162–163 Some desert mammals, such as camels, use dense fur to prevent solar heat from reaching their skin, allowing the animal to stay cool; a camel's fur may reach 70 °C (158 °F) in the summer, but the skin stays at 40 °C (104 °F).[3]: 188 Aquatic mammals,conversely, trap air in their fur to conserve heat by keeping the skin dry.[3]: 162–163 

Aleopard'sdisruptively coloredcoat providescamouflagefor thisambush predator.

Mammalian coats are colored for a variety of reasons, the major selective pressures includingcamouflage,sexual selection,communication, and physiological processes such as temperature regulation. Camouflage is a powerful influence in many mammals, as it helps to conceal individuals from predators or prey.[4]Aposematism,warning off possible predators, is the most likely explanation of the black-and-white pelage of many mammals which are able to defend themselves, such as in the foul-smellingskunkand the powerful and aggressivehoney badger.[5]In arctic and subarctic mammals such as thearctic fox(Vulpes lagopus),collared lemming(Dicrostonyx groenlandicus),stoat(Mustela erminea), andsnowshoe hare(Lepus americanus),seasonal color changebetween brown in summer and white in winter is driven largely by camouflage.[6]Differences in female and male coat color may indicate nutrition and hormone levels, important in mate selection.[7]Some arboreal mammals, notably primates and marsupials, have shades of violet, green, or blue skin on parts of their bodies, indicating some distinct advantage in their largelyarborealhabitat due toconvergent evolution.[8]The green coloration of sloths, however, is the result of asymbioticrelationship with algae.[9]Coat color is sometimessexually dimorphic,as inmany primate species.[10]Coat color may influence the ability to retain heat, depending on how much light is reflected. Mammals with darker colored coats can absorb more heat from solar radiation and stay warmer; some smaller mammals, such asvoles,have darker fur in the winter. The white, pigmentless fur of arctic mammals, such as the polar bear, may reflect more solar radiation directly onto the skin.[3]: 166–167 [2]

Opossumfur

The termpelage– first known use in Englishc. 1828(French, from Middle French, frompoilfor 'hair', fromOld Frenchpeilss,fromLatinpilus[11]) – is sometimes used to refer to an animal's completecoat.The term fur is also used to refer to animal pelts that have been processed into leather with their hair still attached. The wordsfurorfurryare 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". If layered, rather than grown as a singlecoat,it may consist of short down hairs, longguard hairs,and in some cases, mediumawn hairs.Mammals with reduced amounts of fur are often called "naked", as with thenaked mole-rat,or "hairless", as withhairless dogs.

An animal with commercially valuable fur is known within thefur industryas afurbearer.[12]The use offur as clothingor decoration is controversial;animal welfareadvocates object to the trapping and killing of wildlife, and the confinement and killing of animals onfur farms.

Composition

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Down, awn and guard hairs of a domestic tabby cat

The modern mammalian fur arrangement is known to have occurred as far back asdocodonts,haramiyidansandeutriconodonts,with specimens ofCastorocauda,MegaconusandSpinolestespreserving compound follicles with both guard hair and underfur.

Fur may consist of three layers, each with a different type of hair.

Down hair

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Down hair(also known asunderfur,undercoat,underhairorground hair) is the bottom – or inner – layer, composed of wavy or curly hairs with no straight portions or sharp points. Down hairs, which are also flat, tend to be the shortest and most numerous in the coat.Thermoregulationis the principal function of the down hair, which insulates a layer of dry air next to the skin.

Awn hair

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Main article:Awn hair

Theawn haircan be thought of as a hybrid, bridging the gap between the distinctly different characteristics of down and guard hairs. Awn hairs begin their growth much like guard hairs, but less than halfway to their full length, awn hairs start to grow thin and wavy like down hair. Theproximalpart of the awn hair assists in thermoregulation (like the down hair), whereas thedistalpart can shed water (like the guard hair). The awn hair's thin basal portion does not allow the amount ofpiloerectionthat the stiffer guard hairs are capable of. Mammals with well-developed down and guard hairs also usually have large numbers of awn hairs, which may even sometimes be the bulk of the visible coat.

Guard hair

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Main article:Guard hair

Guard hair(overhair[13]) is the top—or outer—layer of the coat. Guard hairs are longer, generally coarser, and have nearly straight shafts that protrude through the layer of softer down hair. Thedistalend of the guard hair is the visible layer of most mammal coats. This layer has the most markedpigmentationandgloss,manifesting as coat markings that are adapted forcamouflageor display. Guard hair repels water and blocks sunlight, protecting the undercoat and skin in wet or aquatic habitats, and from the sun'sultravioletradiation. Guard hairs can also reduce the severity ofcuts or scratchesto the skin. Many mammals, such as the domestic dog and cat, have apilomotor reflexthat raises their guard hairs as part of athreat displaywhen agitated.

Mammals with reduced fur

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Computer generated image of wet fur

Hair is one of the defining characteristics of mammals; however, several species or breeds have considerably reduced amounts of fur. These are often called "naked"[citation needed]or "hairless".[14]

Natural selection

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Some mammals naturally have reduced amounts of fur. Somesemiaquaticoraquaticmammals such ascetaceans,pinnipedsandhippopotamuseshave evolved hairlessness, presumably to reduce resistance through water. Thenaked mole-rathas evolved hairlessness, perhaps as an adaptation to their subterranean lifestyle. Two of the largest extant terrestrial mammals, theelephantand therhinoceros,are largely hairless. Thehairless batis mostly hairless but does have short bristly hairs around its neck, on its front toes, and around the throat sac, along with fine hairs on the head and tail membrane. Most hairless animals cannot go in the sun for long periods of time, or stay in the cold for too long.[15]Marsupialsare born hairless and grow out fur later in development.

Humansare the onlyprimatespecies that have undergone significant hair loss. The hairlessness of humans compared to related species may be due to loss of functionality in thepseudogeneKRTHAP1 (which helps producekeratin)[16]Although the researchers dated the mutation to 240 000 ya, both theAltaiNeandertalandDenisovanpeoples possessed the loss-of-function mutation, indicating it is much older. Mutations in the gene HR can lead tocomplete hair loss,though this is not typical in humans.[17]

Artificial selection

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At times, when a hairless domesticated animal is discovered, usually owing to a naturally occurring genetic mutation, humans may intentionally inbreed those hairless individuals and, after multiple generations, artificially create hairless breeds. There are several breeds of hairless cats, perhaps the most commonly known being theSphynx cat.Similarly, there are some breeds ofhairless dogs.Other examples of artificially selected hairless animals include thehairless guinea-pig,nude mouse,and thehairless rat.

Use in clothing

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Main article:Fur clothing
See also:Fur trade

Fur has long served as a source of clothing for humans, includingNeanderthals.Historically, it was worn for its insulating quality, with aesthetics becoming a factor over time. Pelts were worn in or out, depending on their characteristics and desired use. Today fur and trim used in garments may be dyed bright colors or to mimic exotic animal patterns, or shorn close likevelvet.The term "a fur" may connote a coat, wrap, or shawl.

The manufacturing of fur clothing involves obtaining animal pelts where the hair is left on the animal's processed skin. In contrast, makingleatherinvolves removing the hair from the hide or pelt and using only the skin.

Fur is also used to makefelt.A common felt is made from beaver fur and is used inbowler hats,top hats,and high-endcowboy hats.[18]

Common furbearersused includefox,rabbit,mink,muskrat,leopard,beaver,ermine,otter,sable,jaguar,seal,coyote,chinchilla,raccoon,lemur,andpossum.

See also

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References

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  1. ^"Fur | animal skin".Encyclopedia Britannica.Retrieved2018-10-30.
  2. ^abDawson, T. J.; Webster, K. N.; Maloney, S. K. (2014). "The fur of mammals in exposed environments; do crypsis and thermal needs necessarily conflict? The polar bear and marsupial koala compared".Journal of Comparative Physiology B.184(2): 273–284.doi:10.1007/s00360-013-0794-8.PMID24366474.S2CID9481486.
  3. ^abcdeFeldhamer, George A.; Drickamer, Lee C.; Vessey, Stephen H.; Merritt, Joseph H.; Krajewski, Carey (2007).Mammalogy: Adaptation, Diversity, Ecology(3 ed.). Baltimore: Johns Hopkins University Press.ISBN978-0-8018-8695-9.OCLC124031907.
  4. ^Caro, Tim (2005)."The Adaptive Significance of Coloration in Mammals".BioScience.55(2): 125–136.doi:10.1641/0006-3568(2005)055[0125:tasoci]2.0.co;2.
  5. ^Caro, Tim (February 2009)."Contrasting coloration in terrestrial mammals".Philos Trans R Soc B.364(1516): 537–548.doi:10.1098/rstb.2008.0221.PMC2674080.PMID18990666.
  6. ^Mills, L. Scott; Zimova, Marketa; Oyler, Jared; Running, Steven; Abatzoglou, John T.; Lukacs, Paul M. (April 2013)."Camouflage mismatch in seasonal coat color due to decreased snow duration".PNAS.110(8): 7360–7365.Bibcode:2013PNAS..110.7360M.doi:10.1073/pnas.1222724110.PMC3645584.PMID23589881.
  7. ^Bradley, Brenda; et al. (2012)."Coat Color Variation and Pigmentation Gene Expression in Rhesus Macaques (Macaca Mulatta)"(PDF).Journal of Mammalian Evolution.20(3): 263–70.doi:10.1007/s10914-012-9212-3.S2CID13916535.Archived fromthe original(PDF)on 2015-09-24.
  8. ^Prum, Richard O.; Torres, Rodolfo H. (2004)."Structural colouration of mammalian skin: convergent evolution of coherently scattering dermal collagen arrays"(PDF).Journal of Experimental Biology.207(12): 2157–72.doi:10.1242/jeb.00989.hdl:1808/1599.PMID15143148.S2CID8268610.
  9. ^Suutari, Milla; Majaneva, Markus; Fewer, David P.; Voirin, Bryson;Aiello, Annette;Friedl, Thomas; Chiarello, Adriano G.; Blomster, Jaanika (2010)."Molecular evidence for a diverse green algal community growing in the hair of sloths and a specific association withTrichophilus welckeri(Chlorophyta, Ulvophyceae) ".Evolutionary Biology.10(86): 86.Bibcode:2010BMCEE..10...86S.doi:10.1186/1471-2148-10-86.PMC2858742.PMID20353556.
  10. ^Plavcan, J. M. (2001)."Sexual dimorphism in primate evolution".American Journal of Physical Anthropology.116(33): 25–53.doi:10.1002/ajpa.10011.PMID11786990.S2CID31722173.
  11. ^"Pelage".Merriam-Webster.RetrievedJanuary 9,2013.
  12. ^Peterson, Judy Monroe (2011-01-15).Varmint Hunting.The Rosen Publishing Group.ISBN9781448823666.
  13. ^B. J. Teerink.Hair of West European mammals: atlas and identification key.Cambridge: Cambridge University Press, 2003.
  14. ^Dean, Matthew D (30 December 2022)."Evolution: How (some) mammals lost their hair".eLife.11:e84865.doi:10.7554/eLife.84865.PMC9803347.Retrieved22 July2023.
  15. ^Thomson, Paul (2002)."Cheiromeles torquatus".Animal Diversity Web.Retrieved29 October2013.
  16. ^Winter, H.; Langbein, L.; Krawczak, M.; Cooper, D. N.; Jave-Suarez, L. F.; Rogers, M. A.; Praetzel, S.; Heidt, P. J.; Schweizer, J. (2001). "Human type I hair keratin pseudogene phihHaA has functional orthologs in the chimpanzee and gorilla: Evidence for recent inactivation of the human gene after the Pan-Homo divergence".Human Genetics.108(1): 37–42.doi:10.1007/s004390000439.PMID11214905.S2CID21545865.
  17. ^Abbasi, Amir Ali (2011)."Molecular evolution of HR, a gene that regulates the postnatal cycle of the hair follicle".Scientific Reports.1:32.Bibcode:2011NatSR...1E..32A.doi:10.1038/srep00032.PMC3216519.PMID22355551.
  18. ^Chamber's journal, Published by Orr and Smith, 1952, p. 200, Original from the University of Michigan.
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Wikimedia Commons has media related toFurs.
"Fur-Bearing Animals".Encyclopedia Americana.1920.

"Fur-Bearing Animals".New International Encyclopedia.1905.

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