Journal of Ornithology

, Volume 155, Issue 2, pp 323–336 | Cite as

Feather structure, biomechanics and biomimetics: the incredible lightness of being

Review

Abstract

Millions of years of biological evolution have produced efficient materials and structures that are a source of inspiration to engineers. The paper reviews the overall design principles in the feather rachis and elaborates upon recent functional interpretations. It concentrates on recent findings that shed new light on feather microstructure and on how keratin fibres in a protein matrix are arranged in intricate ways to achieve specific combinations of stiffness and strength on the one hand and flexibility and elasticity on the other. This includes the syncitial barbule cells of the rachis and barb cortex, the crossed-fibre architecture of the epicortex (lateral walls of the cortex), and the foam-like structure of the medullary pith. Discussion of the biomechanics of feather microstructure uses engineering principles for a better understanding of the functional ramifications. Further research is proposed with respect to feather micro- and macrostructure in trying to expand our knowledge on bird flight, behaviour and ecology in different species. The discussion also considers the validity of a study purporting to use quantitative methods and engineering principles to show that the iconic fossil bird Archaeopteryx was incapable of flapping flight.

Keywords

Feather microstructure Biomechanics  Biomimetics Avian β-keratin Archaeopteryx flapping flight? 

Zusammenfassung

Federstruktur, Biomechanik und Bionik: die unglaubliche Leichtigkeit des Seins

Im Laufe von Jahrmillionen sind durch biologische Evolution leistungsfähige Materialien und Strukturen entstanden, die für Ingenieure eine Quelle der Inspiration darstellen. Diese Arbeit fasst die allgemeinen mikrostrukturellen Bauprinzipien des Federschaftes zusammen und geht ausführlicher auf neuere funktionelle Deutungen ein. Der Schwerpunkt liegt dabei auf jüngeren Erkenntnissen, die ein neues Licht auf die Mikrostruktur der Feder werfen und darauf, wie Keratinfasern in einer Proteinmatrix auf komplexe Art angeordnet sind, um bestimmte Konstellationen von Starrheit und Festigkeit einerseits und Biegsamkeit und Elastizität andererseits zu erreichen. Dies umfasst auch die synzytialen Strahlzellen des Cortex von Federschaft und Federästen und die aus überkreuzten Fasern bestehende Bauweise des Epicortex (die seitlichen Wände des Cortex) sowie die schaumstoffähnliche Struktur des Marks. Für ein besseres Verständnis der funktionalen Verzweigungen diskutieren wir die Biomechanik der Federmikrostruktur anhand von bautechnischen Prinzipien. Wir empfehlen weitere Forschung bezüglich der Mikro- und Makrostruktur von Federn, um unser Wissen über den Vogelflug, das Verhalten und die Ökologie verschiedener Arten zu erweitern. In der Diskussion prüfen wir ebenfalls die Aussagekraft einer Studie, welche angibt, mittels quantitativer Methoden und Prinzipien aus der Bautechnik zeigen zu können, dass der legendäre fossile Vogel Archaeopteryx nicht zum Schlagflug befähigt war.

Supplementary material

10336_2013_1038_MOESM1_ESM.jpg (37 kb)
SI Figure 1. Unstressed rachis. The section shows varying diameters of the syncitial barbule cells depending on whether they are transected closer to the nodes or further away because of staggering of the syncitial barbule cells along the rachis length. At least two syncitial barbule cells can be seen (white arrows), the lower one given its size is probably transected at its widest point. Scale bar = 1 μm. (JPEG 37 kb)

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Copyright information

© Dt. Ornithologen-Gesellschaft e.V. 2013

Authors and Affiliations

  1. 1.Life SciencesUniversity of KwaZulu-NatalDurbanSouth Africa
  2. 2.Biological SciencesNelson Mandela Metropolitan UniversityPort ElizabethSouth Africa

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