Editing Scute

{{Short description|Type of scale}}
{{for|the watercraft known as a scute|Galiot}}
[[File:Alligator foot detail.jpg|thumb|right|Scutes on an [[alligator]] foot]]
A '''scute''' ({{IPAc-en|audio=en-us-scute.oga|s|k|j|uː|t|}}) or '''scutum''' ([[Latin]]: ''scutum''; plural: ''scuta'' "[[Scutum (shield)|shield]]") is a bony external plate or scale overlaid with horn, as on the shell of a [[turtle]], the skin of [[crocodilia]]ns, and the feet of [[Bird anatomy#Scales|birds]]. The term is also used to describe the anterior portion of the [[mesothorax]] in [[insect]]s as well as some arachnids (e.g., the family [[Ixodidae]], the scale ticks).

==Properties==
[[File:Scute of the carapace of a Texas tortoise Gopherus berlandieri.jpg|thumb|303x303px|'''Scute of the [[carapace]] of a [[Texas tortoise]]''']]
[[File:The Childrens Museum of Indianapolis - Glyptodon scute - detail.jpg|alt=|thumb|This detail of a ''[[Glyptodon]]'' displays its scutes. From the collection of the [[Children's Museum of Indianapolis]].]]
Scutes are similar to [[scale (zoology)|scales]] and serve the same function. Unlike the scales of lizards and snakes, which are formed from the [[Epidermis (skin)|epidermis]], scutes are formed in the lower vascular layer of the skin and the epidermal element is only the top surface {{Citation needed|date=August 2015}}. Forming in the living [[dermis]], the scutes produce a [[Horn (anatomy)|horny]] outer layer that is superficially similar to that of scales. Scutes will usually not overlap as [[snake scales]] (but see the [[pangolin]]). The outer [[keratin]] layer is shed piecemeal, and not in one continuous layer of skin as seen in snakes or lizards. The dermal base may contain [[bone]] and produce [[Armour (zoology)|dermal armour]]. Scutes with a bony base are properly called ''[[osteoderm]]s''. Dermal scutes are also found in the feet of [[birds]] and tails of some [[mammals]], and are believed to be the primitive form of dermal armour in reptiles.

The term is also used to describe the heavy armour of the [[armadillo]] and the extinct ''[[Glyptodon]]'', and is occasionally used as an alternative to scales in describing [[snake scales|snakes]] or certain fishes, such as [[sturgeon]]s, shad, herring, and menhaden.

==Mammals==
Prehistoric ancestors of mammals, the [[synapsids]], are thought to have scutes which were later reduced and replaced by hair. Excluding the attachment surface of [[fingernail]]s, armoured scutes or scales are almost never seen in modern [[mammals]]. The [[Horn (anatomy)|horny]] scales of [[pangolin]]s are only rarely called scutes, but "scute" is used to describe the heavy armour of the [[armadillo]].

==Turtles==
{{main|Turtle shell}}

The [[Turtle shell|turtle's shell]] is covered by scutes formed mostly of [[keratin]]. They are built similarly to horn, beak, or nail in other species.

==Fish==
[[File:Monocentris japonica 001.jpg|thumb|The [[pineconefish]]]]
Some fish, such as [[pineconefish]], are completely or partially covered in large armored scales commonly termed scutes.<ref>{{cite web|url=https://blogs.ifas.ufl.edu/santarosaco/2012/12/19/seasons-greetings/|title=“Sea”sons Greetings!|website=University of Florida Institute of Food and Agricultural Sciences|date=19 December 2012|access-date=8 January 2025|author=((User chrismv))}}</ref> Many [[Clupeomorpha]] have an abdominal row of scutes, which are scales with raised, sharp points that are used for protection, and in some cases they also possess dorsal scutes anterior to the dorsal fin, as in ''[[Knightia]]'' spp., ''[[Diplomystus]]'' spp. and certain extant taxa.<ref>{{cite book|last1=Lecointre|first1=G.|last2=Nelson|first2=G.|chapter=Chapter 10 - Clupeomorpha, Sister-Group of Ostariophysi|title=Interrelationships of Fishes|year=1996|pages=193-207|publisher=Academic Press|doi=10.1016/B978-012670950-6/50011-4|editor-last1=Stiassny|editor-first1=M.L.J.|editor-last2=Parenti|editor-first2=L.R.|editor-last3=Johnson|editor-first3=G.D.|isbn=978-0-12-670950-6}}</ref>  Jacks of family [[Carangidae]] often have a row of scutes following the [[lateral line]] on either side.<ref>{{cite web|url=https://biogeodb.stri.si.edu/sftep/en/thefishes/taxon/1240|title=Family: CARANGIDAE, Jacks, Amberjacks, Crevalles, Jack-Mackerels, Leatherjackets, Lookdowns, Pilot-Fishes, Pompanos, Scads, Trevallies|website=Shorefishes of the Eastern Pacific online information system|publisher=Smithsonian Tropical Research Institute|year=2023|access-date=8 January 2025}}</ref>  ''[[Coelorinchus]]'' spp. have scutes suborbitally from their [[preoperculum]] extending anteriorly onto a triangular snout.<ref>{{cite book|last1=Marshall|first1=N.B.|last2=Iwamoto|first2=T.|chapter=Genus ''Coelorhynchus'' Giorna 1809|publisher=Yale University Press|pages=538-564|title=Fishes of the Western North Atlantic Part 6: Orders Heteromi (Notacanthiformes), Berycomorphi (Beryciformes), Xenoberyces (Stephanoberyciformes), Anacanthini (Gadiformes)|editor-last1=Cohen|editor-first1=D.M.|editor-last2=Ebeling|editor-first2=A.W.|editor-last3=Iwamoto|editor-first3=T.|editor-last4=McDowell|editor-first4=S.B.|editor-last5=Marshall|editor-first5=N.B.|editor-last6=Rosen|editor-first6=D.E.|editor-last7=Sonoda|editor-first7=P.|editor-last8=Weed III|editor-first8=W.H.|editor-last9=Woods|editor-first9=L.P.|series=Memoir 1, Sears Foundation for Marine Research|isbn=978-1-933789-16-3|doi=10.2307/j.ctvbcd0bn.11|year=1973}}</ref>  [[Sturgeon]] have five rows of scutes—modified [[ganoid scale]]s—and are otherwise scaleless.<ref>{{cite web|url=https://www.fisheries.noaa.gov/new-england-mid-atlantic/endangered-species-conservation/scutes-student-resources|title=Endangered Species Conservation: SCUTES Student Resources|website=NOAA Fisheries|author=Greater Atlantic Regional Fisheries Office|date=26 April 2022|access-date=8 January 2025}}</ref><ref>{{cite web|url=https://www.dfw.state.or.us/fish/license_permits_apps/docs/Sturgeon%20Manual.pdf|title=Manual on Sturgeon Reproduction|publisher=Coppens International bv|access-date=8 January 2025|via=Oregon Department of Fish and Wildlife}}</ref>

==Birds==

The [[tarsometatarsus]] and toes of most birds are covered in two types of scales. Large scutes run along the dorsal side of the tarsometatarsus and toes, whereas smaller scutellae run along the sides. Both structures share histochemical homology with reptilian scales; however, work on their evolutionary development has revealed that the scales in bird feet have secondarily evolved via suppression of the feather-building genetic program.<ref name="SawKnap2003">Sawyer, R.H., Knapp, L.W. 2003. Avian Skin Development and the Evolutionary Origin of Feathers. J. Exp. Zool (Mol Dev Evol) 298B:57–72.</ref><ref name="Sawyeretal05">{{cite journal | last1 = Sawyer | first1 = R.H. | last2 = Rogers | first2 = L. | last3 = Washington | first3 = L. | last4 = Glenn | first4 = T.C. | last5 = Knapp | first5 = L.W. | year = 2005 | title = Evolutionary Origin of the Feather Epidermis | journal = Dev. Dyn. | volume = 232 | issue = 2| pages = 256–267 | doi=10.1002/dvdy.20291| pmid = 15637693 | s2cid = 44477271 | doi-access = free }}</ref><ref name="Dhouailly09">{{cite journal | last1 = Dhouailly | first1 = D | year = 2009 | title = A new scenario for the evolutionary origin of hair, feather, and avian scales | url =http://www.hal.inserm.fr/docs/00/38/16/27/PDF/inserm-00381627_edited.pdf | journal = Journal of Anatomy | volume = 214 | issue = 4| pages = 587–606 | doi=10.1111/j.1469-7580.2008.01041.x | pmid=19422430 | pmc=2736124}}</ref> Unblocking the feather suppression program results in feathers growing in place of scales along the tarsometatarsus and toes.<ref name="SawKnap2003" /><ref name="Sawyeretal05" /><ref name="Dhouailly09" /> Dinosaur species very close to the origin of birds have been shown to have had "hind wings" made of feathers growing from these areas, suggesting that the acquisition of feathers in dinosaurs was a whole-body event.<ref name="Dhouailly09" /> The bottoms of bird feet are covered in small, keeled scale-like structures known as reticulae. Evolutionary developmental studies on these scale-like structures have revealed that they are composed entirely of alpha keratin (true epidermal scales are composed of a mix of alpha and beta keratin).<ref name="Dhouailly09" /> These data have led some researchers to suggest that reticulae are in fact highly truncated feathers.<ref name="Dhouailly09" /><ref>{{cite journal | last1 = Zheng | first1 = X. | last2 = Zhou | first2 = Z. | last3 = Wang | first3 = X. | last4 = Zhang | first4 = F. | last5 = Zhang | first5 = X. | last6 = Wang | first6 = Y. | last7 = Xu | first7 = X. | year = 2013 | title = Hind wings in basal birds and the evolution of leg feathers | journal = Science | volume = 339 | issue = 6125| pages = 1309–1312 | doi=10.1126/science.1228753 | pmid=23493711| bibcode = 2013Sci...339.1309Z | citeseerx = 10.1.1.1031.5732 | s2cid = 206544531 }}</ref>

==Insects and other arthropods==
The term "scutum" is also used in [[insect]] anatomy, as an alternative name for the anterior portion of the [[mesonotum]] (and, technically, the [[metanotum]], though rarely applied in that context).
[[File:Amblyomma-variegatum-female.jpg|thumb|{{center|Conspicuous '''scutum''' on a typical female hard tick before she has fed. Note the pale eye-spots near the edges of the scutum, roughly between the 2nd and 3rd legs}}]]
[[File:Amblyomma-variegatum-female-engorged.jpg|thumb|{{center|The same '''scutum''' is relatively less conspicuous after the tick has fed, because it has not changed in size, whereas the tick has swollen as it [[Wiktionary:engorge|engorge]]d}}]]
[[File:Amblyomma male dorsal.jpg|thumb|{{center|In the typical male hard tick, the '''conscutum''' covers practically the whole back}}]]
In the [[hard tick]]s, the [[Ixodidae]], the scutum is a rigid, [[Sclerotin|sclerotised]] plate on the [[Anatomical_terms_of_location#Anterior_and_posterior|anterior]] [[Anatomical_terms_of_location#Dorsal_and_ventral|dorsal]] surface, just [[Anatomical_terms_of_location#Anterior_and_posterior|posterior]] to the head. In species with eyes, the eyes are on the surface of the scutum. The flexible [[exoskeleton]] posterior to the rigid scutum of the female tick, is called the '''alloscutum''', the region that stretches to accommodate the blood with which the mature female tick becomes [[Wiktionary:engorge|engorge]]d. Males do not engorge nearly as drastically as females, so they do not need a flexible alloscutum; instead the rigid scutum covers practically the entire dorsal surface posterior to the head, and may be referred to specifically as the '''conscutum'''.<ref name="HorakHeyne2018">{{cite book|author1=Ivan G. Horak|author2=Heloise Heyne|author3=Roy Williams |author4=G. James Gallivan |author5=Arthur M. Spickett |author6=J. Dürr Bezuidenhout |author7=Agustín Estrada-Peña |title=The Ixodid Ticks (Acari: Ixodidae) of Southern Africa|url=https://books.google.com/books?id=2TtMDwAAQBAJ&pg=PA46|date=14 February 2018|publisher=Springer|isbn=978-3-319-70642-9|pages=46–}}</ref> 

In some species of [[Opiliones]], fused abdominal segments are referred to as a scutum.<ref>{{cite journal |author1=Ricardo Pinto-da-Rocha |author2=Rafael Fonseca-Ferreira |author3=Maria Bichuette |title=A new highly specialized cave harvestman from Brazil and the first blind species of the genus: ''Iandumoema smeagol'' sp. n. (Arachnida, Opiliones, Gonyleptidae) |journal=[[ZooKeys]] |date=18 November 2015 |issue=537 |pages=79–95 |doi=10.3897/zookeys.537.6073 |pmid=26798238 |pmc=4714048|doi-access=free }}</ref>

==See also==
* [[Fish scale#Scutes|Fish scutes]]
* [[Osteoderms]]
* [[Scale (zoology)]]
* [[Snake scales]]
* [[Keratin]]
* [[Skin]]
* [[Skeleton]]

==References==
{{reflist}}

[[Category:Animal anatomy]]
[[Category:Dinosaur anatomy]]

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