WordNet
- scalelike structure between the base of the wing and the halter of a two-winged fly (同)calypter
- pertaining to alulae
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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/12/16 02:12:16」(JST)
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This article is about the anatomy of a bird's wing. For other uses, see Alula (disambiguation).
Location of the alula on a bird's wing
The alula, or bastard wing, (plural alulae) is a small projection on the anterior edge of the wing of modern birds and a few non-avian dinosaurs. The word is Latin and means "winglet"; it is the diminutive of ala, meaning "wing". The alula is the freely moving first digit, a bird's "thumb", and typically bears three to five small flight feathers, with the exact number depending on the species. There also are minor covert feathers overlying the flight feathers. Like the larger flight feathers found on the wing's trailing edge, these alula feathers are asymmetrical, with the shaft running closer to anterior edge.
Contents
- 1 Function
- 2 Alula in ancient birds
- 3 See also
- 4 Citations
- 5 References
Function
Adult bald eagle landing, showing the alula in action
In most situations, the alula is held flush against the wing; however, it can be manipulated. When flying at slow speeds or landing, the bird moves its alula slightly upwards and forward, which creates a small slot on the wing's leading edge. This functions in the same way as the slats on the wing of an aircraft, allowing the wing to achieve a higher than normal angle of attack – and thus lift – without resulting in a stall.[1] The tip of the alula forms a tiny vortex that forces the airflow over the wing to better bind to it. [2][3] During stretching of the wing down toward the ground, the alula is abducted from the wing and can be clearly viewed.
Alula in ancient birds
The presence of an alula has been confirmed in several now-extinct ancient relatives of modern birds, including Eoalulavis hoyasi (an enantiornithine from the mid-Cretaceous, 115[4] mya) and the earlier Protopteryx fengningensis.[5] Since these species are not closely related to modern birds, either the alula evolved twice, or it did so more than 130 million years ago.
See also
- Bird flight
- Alular digit homology
- Leading edge slot, the man-made equivalent on fixed-wing aircraft
Citations
- ^ Ehrlich et al. 1994, p. 219
- ^ "Small vortex on wing makes the elegance of birds' flight". Retrieved 5 June 2015.
- ^ "A small vortex on the wing makes the elegance of birds' flight".
- ^ Sanz et al. 1996
- ^ Zhang, Zhou & 8 December 2000
References
- Ehrlich, Paul R; Dobkin, David S.; Wheye, Darryl; Pimms, Stuart L. (1994), The Birdwatcher's Handbook, Oxford University Press, ISBN 0-19-858407-5
- Sanz, J. L.; Chiappe, L. M.; Pérez-Moreno, B. P.; Buscalioni, A. D.; Moratalla, J. J.; Ortega, F.; Poyato-Ariza, F. J. (1996-08-01), "An Early Cretaceous bird from Spain and its implications for the evolution of avian flight", Nature, 382 (6590): 442–445, doi:10.1038/382442a0
- Zhang, Fucheng; Zhou, Zhonghe (8 December 2000), "A Primitive Enantiornithine Bird and the Origin of Feathers", Science, 290 (5498): 1955–1959, doi:10.1126/science.290.5498.1955, PMID 11110660
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Feather tracts
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- alula
- coverts
- crown
- eye-ring
- flight feathers
- mantle
- nape
- scapulars
- speculum
- supercilium
|
English Journal
- The function of the alula in avian flight.
- Lee SI1, Kim J2, Park H3, Jabłoński PG4, Choi H3.
- Scientific reports.Sci Rep.2015 May 7;5:9914. doi: 10.1038/srep09914.
- The alula is a small structure located at the joint between the hand-wing and arm-wing of birds and is known to be used in slow flight with high angles of attack such as landing. It is assumed to function similarly to a leading-edge slat that increases lift and delays stall. However, in spite of its
- PMID 25951056
- Morphological properties of the last primaries, the tail feathers, and the alulae of Accipiter nisus, Columba livia, Falco peregrinus, and Falco tinnunculus.
- Schmitz A1, Ponitz B, Brücker C, Schmitz H, Herweg J, Bleckmann H.
- Journal of morphology.J Morphol.2015 Jan;276(1):33-46. doi: 10.1002/jmor.20317. Epub 2014 Aug 4.
- We investigated the mechanical properties (Young's modulus, bending stiffness, barb separation forces) of the tenth primary of the wings, of the alulae and of the middle tail feathers of Falco peregrinus. For comparison, we also investigated the corresponding feathers in pigeons (Columba livia), kes
- PMID 25130288
- Photochemical decoration of magnetic composites with silver nanostructures for determination of creatinine in urine by surface-enhanced Raman spectroscopy.
- Alula MT1, Yang J2.
- Talanta.Talanta.2014 Dec;130:55-62. doi: 10.1016/j.talanta.2014.06.047. Epub 2014 Jun 30.
- In this study, silver nanostructures decorated magnetic nanoparticles for surface-enhanced Raman scattering (SERS) measurements were prepared via photoreduction utilizing the catalytic activity of ZnO nanostructure. The ZnO/Fe3O4 composite was first prepared by dispersing pre-formed magnetic nanopar
- PMID 25159379
Japanese Journal
- SCHOLARSHIP ON ETHIOPIAN MUSIC: PAST, PRESENT AND FUTURE PROSPECTS
- African study monographs. Supplementary issue 41, 19-34, 2010-03-31
- NAID 110007523219
- SCHOLARSHIP ON ETHIOPIAN MUSIC: PAST, PRESENT AND FUTURE PROSPECTS
- 羽根の小羽枝構造によるガン類ハクチョウ類カモ類の識別について
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