Orbit orientation and eye morphometrics in giraffes (Giraffa camelopardalis)

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dc.contributor.author Mitchell, Graham
dc.contributor.author Roberts, D.G.
dc.contributor.author Van Sittert, Sybrand J.
dc.contributor.author Skinner, J.D. (John Dawson), 1932-
dc.date.accessioned 2014-03-10T10:27:19Z
dc.date.available 2014-10-30T00:20:05Z
dc.date.issued 2013-10
dc.description.abstract Giraffe are thought to have excellent vision.We measured eye size, orbit orientation and retina surface area in 27 giraffes of both sexes ranging in age from neonates to mature adults (>10 yrs), to assess how it changes with growth, whether their eye anatomy correlates with their apparently excellent vision and lifestyle, and we have compared our findings with those for other large mammals to assess whether giraffe eye anatomy is unique.We found that giraffe eye volume increases from 33 cm3 at birth to approximately 65 cm3 in adults. The focal (axial) length increases from c. 40 to 48 mm in adults and retina surface area from c. 3000 mm2 at birth to 4320 mm2 in adults. The orbital axis angle at birth is c. 73° and the horizontal visual field mainly monocular and panoramic.With age the axis angle becomes more acute to c. 50° in adults and the visual field more binocular, changes that occur concurrently with increasing neck length. These results show that the giraffe eye and retinal surface area are larger than in all other ungulates, and their visual fields more binocular, attributes which are consistent with the idea that they have excellent vision. en
dc.description.librarian am2014 en
dc.description.librarian mn2014
dc.description.sponsorship The Don Craib Trust (J.D.S.), from a personal research grant (J.D.S.) and the University of Wyoming (G.M.). S.J.v.S. is in receipt of the Maberly Memorial Scholarship and a University of Pretoria study bursary. en
dc.description.uri http://africanzoology.journals.ac.za/ en
dc.identifier.citation Mitchell, G, Roberts, DG, Van Sittert, SJ & Skinner, JD 2013, 'Orbit orientation and eye morphometrics in giraffes (Giraffa camelopardalis)', African Zoology, vol. 48, no. 2, pp. 333-339. en
dc.identifier.issn 1562-7020 (print)
dc.identifier.issn 2224-073X (online)
dc.identifier.uri http://hdl.handle.net/2263/37109
dc.language.iso en en
dc.publisher Zoological Society of Southern Africa en
dc.rights SU LIS en
dc.subject Giraffe en
dc.subject Eye size en
dc.subject Orbit orientation en
dc.subject Visual acuity en
dc.subject.lcsh Giraffe en
dc.title Orbit orientation and eye morphometrics in giraffes (Giraffa camelopardalis) en
dc.type Article en


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