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Flow patterns generated by oblate medusan jellyfish: field measurements and laboratory analyses

Dabiri, John O. and Colin, Sean P. and Costello, John H. and Gharib, Morteza (2005) Flow patterns generated by oblate medusan jellyfish: field measurements and laboratory analyses. Journal of Experimental Biology, 208 (7). pp. 1257-1265. ISSN 0022-0949. http://resolver.caltech.edu/CaltechAUTHORS:20110725-140550989

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Abstract

Flow patterns generated by medusan swimmers such as jellyfish are known to differ according the morphology of the various animal species. Oblate medusae have been previously observed to generate vortex ring structures during the propulsive cycle. Owing to the inherent physical coupling between locomotor and feeding structures in these animals, the dynamics of vortex ring formation must be robustly tuned to facilitate effective functioning of both systems. To understand how this is achieved, we employed dye visualization techniques on scyphomedusae (Aurelia aurita) observed swimming in their natural marine habitat. The flow created during each propulsive cycle consists of a toroidal starting vortex formed during the power swimming stroke, followed by a stopping vortex of opposite rotational sense generated during the recovery stroke. These two vortices merge in a laterally oriented vortex superstructure that induces flow both toward the subumbrellar feeding surfaces and downstream. The lateral vortex motif discovered here appears to be critical to the dual function of the medusa bell as a flow source for feeding and propulsion. Furthermore, vortices in the animal wake have a greater volume and closer spacing than predicted by prevailing models of medusan swimming. These effects are shown to be advantageous for feeding and swimming performance, and are an important consequence of vortex interactions that have been previously neglected.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1242/jeb.01519 DOIUNSPECIFIED
http://jeb.biologists.org/content/208/7/1257PublisherUNSPECIFIED
Additional Information:© 2005 Published by The Company of Biologists. Accepted 31 January 2005. This research is supported by National Science Foundation Grants OCE-0116236 (to J.H.C.) and CTS-0309671 (to M.G.). We gratefully acknowledge helpful comments and suggestions from M. S. Gordon and two anonymous reviewers of this manuscript. We also acknowledge the support of the Ministry of Education, Science and Sport of the Republic of Slovenia, the Ministry of Science, Education and Sport of the Republic of Croatia and the University of Dubrovnik (Croatia).
Funders:
Funding AgencyGrant Number
NSFOCE-0116236
NSFCTS-0309671
Ministry of Education, Science and Sport of the Republic of SloveniaUNSPECIFIED
Ministry of Science, Education and Sport of the Republic of CroatiaUNSPECIFIED
University of Dubrovnik (Croatia)UNSPECIFIED
Subject Keywords:jellyfish; Aurelia aurita; flow pattern; flow patterns; vortex rings; jet propulsion
Record Number:CaltechAUTHORS:20110725-140550989
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20110725-140550989
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:24531
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:06 Oct 2011 21:20
Last Modified:26 Dec 2012 13:25

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