Maneuverability is one of the most important and least understood aspects of animal locomotion. The hydrofoil-like flippers of cetaceans are thought to function as control surfaces that effect maneuvers, but quantitative tests of this hypothesis have been lacking. Here, we constructed a simple hydrodynamic model to predict the longitudinal-axis roll performance of fin whales, and we tested its predictions against kinematic data recorded by on-board movement sensors from 27 free-swimming fin whales. We found that for a given swimming speed and roll excursion, the roll velocity of fin whales calculated from our field data agrees well with that predicted by our hydrodynamic model. Although fluke and body torsion may further influence performance, our results indicate that lift generated by the flippers is sufficient to drive most of the longitudinal-axis rolls used by fin whales for feeding and maneuvering.
The authors declare no competing or financial interests.
P.S.S. refined the model, analyzed the data, and wrote the manuscript. D.E.C. devised the procedures used to prepare the whale tag data for analysis, calculated swimming speeds, contributed to the data collection and assisted with the manuscript preparation. F.E.F. and J.P. designed the hydrodynamic model, conceived the study and assisted with the manuscript preparation. J.A.G. oversaw the whale tag data collection, conceived the study and assisted with the manuscript preparation. A.S.F. and J.A.G. conceived the camera-movement tag design built by CATS. Tagging and fieldwork operations were performed by A.N.A., A.S.F., J.A.G. and J.C.
Funding for the tagging operations in this study was provided by the US Office of Naval Research (ONR) Marine Mammal Program (B. Southall and J.C.). The project used ship time funded largely by the US Navy M45 (Environmental Readiness Division) Living Marine Resources Program (NMFS permit no. 16111). Additional support was provided by the ONR Young Investigator Program (N00014-16-1-2477) awarded to J.A.G. Hydrodynamic characteristics of the flippers were determined in a study funded originally by a grant from the National Science Foundation (IOS-0640185) to F.E.F.
Supplementary information available online at http://jeb.biologists.org/lookup/doi/10.1242/jeb.137091.supplemental
- Received January 10, 2016.
- Accepted August 24, 2016.
- © 2016. Published by The Company of Biologists Ltd