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Revisi per 13 Mei 2012 03.36

Penglihatan adalah indra yang paling penting untuk burung, karena penglihatan yang baik sangat penting bagi penerbangan aman, dan kelompok burung memiliki sejumlah adaptasi yang memberikan ketajaman visual dari kelompok vertebrata lainnya; merpati dideskribsikan sebagai "dua mata dengan sayap".^[1] Mata burung mirip dengan reptil, dengan otot silia yang dapat mengubah bentuk lensa mata dengan cepat dan bertaraf lebih tinggi daripada mamalia. Burung memiliki mata relatif besar untuk seukuran mereka dalam kerajaaan animalia, dan akibatnya gerakannya terbatasa tulang rongga mata.^[1] Selain kedua kelopak mata yang biasanya ditemukan pada vertebrata, itu dilindungi oleh membran transparan yang dapat bergerak ketiga. Anatomi internal mata burung sama dengan vertebrata lain, tapi memiliki struktur, dan pekten okuli, adalah barang unik dalam penglihatan burung.

Anatomi ekstraokular

Referensi

^ ^a ^b Güntürkün, Onur, "Structure and functions of the eye" in Sturkie (1998) 1–18

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[Sturkie-1] Güntürkün, Onur, "Structure and functions of the eye" in Sturkie (1998) 1–18

[1]

@@ Baris 2: / Baris 2: @@
 [[File:Bald Eagle at The National Zoo.jpg|thumb|Dengan mata yang menghadap ke depan, [[elang botak]] memiliki [[penglihatan binokular]] yang luas.]]
 '''Penglihatan''' adalah indra yang paling penting untuk [[burung]], karena penglihatan yang baik sangat penting bagi penerbangan aman, dan kelompok burung memiliki sejumlah adaptasi yang memberikan ketajaman [[visual]] dari kelompok [[vertebrata]] lainnya; [[merpati]] dideskribsikan sebagai "dua mata dengan sayap".<ref name= "Sturkie">Güntürkün, Onur, "Structure and functions of the eye" in Sturkie (1998) 1&ndash;18</ref> Mata burung mirip dengan [[reptil]], dengan otot silia yang dapat mengubah bentuk [[lensa mata]] dengan cepat dan bertaraf lebih tinggi daripada [[mamalia]]. Burung memiliki mata relatif besar untuk seukuran mereka dalam kerajaaan [[animalia]], dan akibatnya gerakannya terbatasa [[tulang]] rongga mata.<ref name= "Sturkie"/> Selain kedua [[kelopak mata]] yang biasanya ditemukan pada vertebrata, itu dilindungi oleh [[membran]] transparan yang dapat bergerak ketiga. Anatomi internal mata burung sama dengan vertebrata lain, tapi memiliki struktur, dan [[pekten okuli]], adalah barang unik dalam penglihatan burung.
+==Anatomi ekstraokular==
+<!--The [[eye]] of a bird most closely resembles that of the reptiles. Unlike the [[mammal]]ian eye, it is not spherical, and the flatter shape enables more of its visual field to be in focus. A circle of bony plates, the [[sclerotic ring]], surrounds the eye and holds it rigid, but an improvement over the reptilian eye, also found in mammals, is that the lens is pushed further forward, increasing the size of the image on the retina.<ref name= "Sinclair">Sinclair (1985) 88&ndash;100</ref>
+[[File:Fieldofview01.png|thumb|left|Fields of view for a pigeon and an owl]]
+Most birds cannot move their eyes, although there are exceptions, such as the [[Great Cormorant]].<ref>{{cite journal |last=White |first=Craig R. |month=July |year=2007 |title=Vision and Foraging in Cormorants: More like Herons than Hawks? |journal=PLoS ONE |volume=2 |issue=7 |pages=e639 |url=http://eprints.bham.ac.uk/55/1/martin.pdf |format=PDF|doi=10.1371/journal.pone.0000639 |pmid=17653266 |last2=Day |first2=N |last3=Butler |first3=PJ |last4=Martin |first4=GR |pmc=1919429 |last5=Bennett |first5=Peter |editor1-last=Bennett |editor1-first=Peter}}</ref> Birds with eyes on the sides of their heads have a wide [[visual field]], useful for detecting predators, while those with eyes on the front of their heads, such as owls, have [[binocular vision]] and can estimate distances when hunting.<ref>{{cite journal |last=Martin |first=Graham R. |year=1999 |title=Visual fields in short-toed eagles, ''Circaetus gallicus'' (Accipitridae), and the function of binocularity in birds |journal=Brain, Behaviour and Evolution |volume=53 |issue=2 |pages=55–66 |doi=10.1159/000006582 |pmid= 9933782 |last2=Katzir |first2=G}}</ref> The [[American Woodcock]] probably has the largest visual field of any bird, 360° in the horizontal plane, and 180° in the vertical plane.<ref name = "Jones"/>
+[[File:Bird blink-edit.jpg|thumb|upright=2.0|The nictitating membrane of a [[Masked Lapwing]]]]
+The eyelids of a bird are not used in blinking. Instead the eye is lubricated by the [[nictitating membrane]], a third concealed eyelid that sweeps horizontally across the eye like a windscreen wiper.<ref>{{cite journal |last=Williams |first=David L.  |month=March |year=2003 |title=Symblepharon with aberrant protrusion of the nictitating membrane in the snowy owl (''Nyctea scandiaca'') |journal=Veterinary Ophthalmology | url = http://www.davidlwilliams.org.uk/resources/file0016.pdf |format=PDF|volume=6 |issue=1 |pages=11&ndash;13 |doi=10.1046/j.1463-5224.2003.00250.x |pmid=12641836 |last2=Flach |first2=E}}</ref> The nictitating membrane also covers the eye and acts as a [[contact lens]] in many aquatic birds when they are under water.<ref name = "Gill">{{cite book |last=Gill |first=Frank |year=1995 |title=Ornithology |publisher=WH Freeman and Co |location=New York |isbn=0-7167-2415-4 |pages= |oclc=30354617}}</ref> When sleeping, the lower eyelid rises to cover the eye in most birds, with the exception of the [[horned owl]]s where the upper eyelid is mobile.<ref>{{cite book|publisher=Henry Holt & Co, New York|year=1906|title=The bird: its form and function|pages=214|url=http://www.archive.org/details/birditsformfunct00beeb|unused_data=Beebe, C. William}}</ref>
+The eye is also cleaned by tear secretions from the [[lachrymal gland]] and protected by an oily substance from the [[Harderian gland]]s which coats the cornea and prevents dryness. The eye of a bird is larger compared to the size of the animal than for any other group of animals, although much of it is concealed in its skull. The [[Ostrich]] has the largest eye of any land vertebrate, with an axial length of 50&nbsp;mm (2&nbsp;in), twice that of the human eye.<ref name= "Sturkie"/>
+Bird eye size is broadly related to body mass. A study of five orders (parrots, pigeons, petrels, raptors and owls) showed that eye mass is proportional to body mass, but as expected from their habits and visual ecology, raptors and owls have relatively large eyes for their body mass.<ref name= "brooke">{{cite journal|last=Brooke |first=M. de L.|month=February |year=1999 |title=The scaling of eye size with body mass in birds |journal=Proceeding of the Royal Society Biological  Sciences |volume=266 |issue= 1417|pages=405&ndash;412 |doi=10.1098/rspb.1999.0652|last2=Hanley|first2=S.|last3=Laughlin|first3=S. B. |pmc=1689681|pmid=}}</ref>
+Behavioural studies show that many avian species focus on distant objects preferentially with their lateral and monocular ﬁeld of vision, and birds will orientate themselves sideways to maximise visual resolution. For a pigeon, resolution is twice as good with sideways monocular vision than forward binocular vision, whereas for humans the converse is true.<ref name= "Sturkie"/>
+[[File:Erithacus-OhWeh-006.jpg|thumb|left|The [[European Robin]] has relatively large eyes, and starts to sing early in the morning.]]
+The performance of the eye in low light levels depends on the distance between the lens and the retina, and small birds are effectively forced to be diurnal because their eyes are not large enough to give adequate night vision. Although many species [[bird migration|migrate]] at night, they often collide with even brightly lit objects like lighthouses or oil platforms. Birds of prey are diurnal because, although their eyes are large, they are optimised to give maximum spatial resolution rather than light gathering, so they also do not function well in poor light.<ref name= "martin">Martin, Graham. "Producing the image" in Ziegler & Bischof (1993) 5&ndash;24</ref> Many birds have an asymmetry in the eye's structure which enables them to keep the horizon and a significant part of the ground in focus simultaneously. The cost of this adaptation is that they have [[myopia]] in the lower part of their field of view.<ref name= "Sturkie"/>
+Birds with relatively large eyes compared to their body mass, such as [[Common Redstart]]s and [[European Robin]]s sing earlier at dawn than birds of the same size and smaller body mass. However, if birds have the same eye size but different body masses, the larger species sings later than the smaller. This may be because the smaller bird has to start the day earlier because of weight loss overnight.<ref name="dawn" >{{cite journal|last=Thomas |first=Robert J. |month= |year=2002 |title=Eye size in birds and the timing of song at dawn|journal=Proceedings  of the Royal society of London |volume=269 |issue=1493 |pages=831&ndash;837 |doi=10.1098/rspb.2001.1941 | pmid = 11958715|last2=Suzuki|first2=M|last3=Saito|first3=S|last4=Tanda|first4=S|last5=Newson|first5=Stuart E.|last6=Frayling|first6=Tim D.|last7=Wallis|first7=Paul D. |pmc=1690967}}</ref>
+Nocturnal birds have eyes optimised for visual sensitivity, with large corneas relative to the eye’s length, whereas diurnal birds have longer eyes relative to the corneal diameter to give greater visual acuity. Information about the activities of extinct species can be deduced from measurements of the sclerotic ring and orbit depth. For the latter measurement to be made, the fossil must have retained its three-dimensional shape, so activity pattern cannot be determined with confidence from flattened specimens like ''[[Archaeopteryx]]'', which has a complete sclerotic ring but no orbit depth measurement.<ref name= "Hall">{{cite journal|last=Hall |first=Margaret I. |coauthors= |month=June |year=2008 |title=The anatomical relationships between the avian eye, orbit and sclerotic ring: implications for inferring activity patterns in extinct birds
+ |journal=Journal of Anatomy |volume=212 |issue=6|pages=781&ndash;794 |url= |format= |doi=10.1111/j.1469-7580.2008.00897.x|pmid=18510506|pmc=2423400 }}</ref>-->
 == Referensi ==