How body torque and Strouhal number change with swimming speed and developmental stage in larval zebrafish

Small undulatory swimmers such as larval zebrafish experience both inertial and viscous forces, the relative importance of which is indicated by the Reynolds number (Re). Re is proportional to swimming speed (vswim) and body length; faster swimming reduces the relative effect of viscous forces. Comp...

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Bibliographic Details
Published inJournal of the Royal Society interface Vol. 12; no. 110; p. 0479
Main Authors van Leeuwen, Johan L., Voesenek, Cees J., Müller, Ulrike K.
Format Journal Article
LanguageEnglish
Published England The Royal Society 06.09.2015
Subjects
Animals
Biomechanical Phenomena
Biomechanics
Body Torque
Danio rerio
Development
Experimental Zoology
Experimentele Zoologie
Larval Zebrafish
Leerstoelgroep Experimentele zoölogie
Models, Biological
Swimming
Swimming - physiology
WIAS
Zebrafish - physiology
body torque
swimming
development
biomechanics
larval zebrafish
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Summary:Small undulatory swimmers such as larval zebrafish experience both inertial and viscous forces, the relative importance of which is indicated by the Reynolds number (Re). Re is proportional to swimming speed (vswim) and body length; faster swimming reduces the relative effect of viscous forces. Compared with adults, larval fish experience relatively high (mainly viscous) drag during cyclic swimming. To enhance thrust to an equally high level, they must employ a high product of tail-beat frequency and (peak-to-peak) amplitude fAtail, resulting in a relatively high fAtail/vswim ratio (Strouhal number, St), and implying relatively high lateral momentum shedding and low propulsive efficiency. Using kinematic and inverse-dynamics analyses, we studied cyclic swimming of larval zebrafish aged 2–5 days post-fertilization (dpf). Larvae at 4–5 dpf reach higher f (95 Hz) and Atail (2.4 mm) than at 2 dpf (80 Hz, 1.8 mm), increasing swimming speed and Re, indicating increasing muscle powers. As Re increases (60 → 1400), St (2.5 → 0.72) decreases nonlinearly towards values of large swimmers (0.2–0.6), indicating increased propulsive efficiency with vswim and age. Swimming at high St is associated with high-amplitude body torques and rotations. Low propulsive efficiencies and large yawing amplitudes are unavoidable physical constraints for small undulatory swimmers.
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ISSN:1742-5689
1742-5662
DOI:10.1098/rsif.2015.0479