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Curvature-induced stiffening of a fish fin

How fish modulate their fin stiffness during locomotive manoeuvres remains unknown. We show that changing the fin's curvature modulates its stiffness. Modelling the fin as bendable bony rays held together by a membrane, we deduce that fin curvature is manifested as a misalignment of the princip...

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Autores principales: Nguyen, Khoi, Yu, Ning, Bandi, Mahesh M., Venkadesan, Madhusudhan, Mandre, Shreyas
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5454310/
https://www.ncbi.nlm.nih.gov/pubmed/28566508
http://dx.doi.org/10.1098/rsif.2017.0247
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author Nguyen, Khoi
Yu, Ning
Bandi, Mahesh M.
Venkadesan, Madhusudhan
Mandre, Shreyas
author_facet Nguyen, Khoi
Yu, Ning
Bandi, Mahesh M.
Venkadesan, Madhusudhan
Mandre, Shreyas
author_sort Nguyen, Khoi
collection PubMed
description How fish modulate their fin stiffness during locomotive manoeuvres remains unknown. We show that changing the fin's curvature modulates its stiffness. Modelling the fin as bendable bony rays held together by a membrane, we deduce that fin curvature is manifested as a misalignment of the principal bending axes between neighbouring rays. An external force causes neighbouring rays to bend and splay apart, and thus stretches the membrane. This coupling between bending the rays and stretching the membrane underlies the increase in stiffness. Using three-dimensional reconstruction of a mackerel (Scomber japonicus) pectoral fin for illustration, we calculate the range of stiffnesses this fin is expected to span by changing curvature. The three-dimensional reconstruction shows that, even in its geometrically flat state, a functional curvature is embedded within the fin microstructure owing to the morphology of individual rays. As the ability of a propulsive surface to transmit force to the surrounding fluid is limited by its stiffness, the fin curvature controls the coupling between the fish and its surrounding fluid. Thereby, our results provide mechanical underpinnings and morphological predictions for the hypothesis that the spanned range of fin stiffnesses correlates with the behaviour and the ecological niche of the fish.
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spelling pubmed-54543102017-06-05 Curvature-induced stiffening of a fish fin Nguyen, Khoi Yu, Ning Bandi, Mahesh M. Venkadesan, Madhusudhan Mandre, Shreyas J R Soc Interface Life Sciences–Engineering interface How fish modulate their fin stiffness during locomotive manoeuvres remains unknown. We show that changing the fin's curvature modulates its stiffness. Modelling the fin as bendable bony rays held together by a membrane, we deduce that fin curvature is manifested as a misalignment of the principal bending axes between neighbouring rays. An external force causes neighbouring rays to bend and splay apart, and thus stretches the membrane. This coupling between bending the rays and stretching the membrane underlies the increase in stiffness. Using three-dimensional reconstruction of a mackerel (Scomber japonicus) pectoral fin for illustration, we calculate the range of stiffnesses this fin is expected to span by changing curvature. The three-dimensional reconstruction shows that, even in its geometrically flat state, a functional curvature is embedded within the fin microstructure owing to the morphology of individual rays. As the ability of a propulsive surface to transmit force to the surrounding fluid is limited by its stiffness, the fin curvature controls the coupling between the fish and its surrounding fluid. Thereby, our results provide mechanical underpinnings and morphological predictions for the hypothesis that the spanned range of fin stiffnesses correlates with the behaviour and the ecological niche of the fish. The Royal Society 2017-05 2017-05-31 /pmc/articles/PMC5454310/ /pubmed/28566508 http://dx.doi.org/10.1098/rsif.2017.0247 Text en © 2017 The Author(s). http://creativecommons.org/licenses/by/4.0/ Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.
spellingShingle Life Sciences–Engineering interface
Nguyen, Khoi
Yu, Ning
Bandi, Mahesh M.
Venkadesan, Madhusudhan
Mandre, Shreyas
Curvature-induced stiffening of a fish fin
title Curvature-induced stiffening of a fish fin
title_full Curvature-induced stiffening of a fish fin
title_fullStr Curvature-induced stiffening of a fish fin
title_full_unstemmed Curvature-induced stiffening of a fish fin
title_short Curvature-induced stiffening of a fish fin
title_sort curvature-induced stiffening of a fish fin
topic Life Sciences–Engineering interface
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5454310/
https://www.ncbi.nlm.nih.gov/pubmed/28566508
http://dx.doi.org/10.1098/rsif.2017.0247
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