Abstract
Drag forces acting on Steller sea lions (Eumetopias jubatus) were investigated from 'deceleration during glide' measurements. A total of 66 glides from six juvenile sea lions yielded a mean drag coefficient (referenced to total wetted surface area) of 0.0056 at a mean Reynolds number of 5.5x10(6). The drag values indicate that the boundary layer is largely turbulent for Steller sea lions swimming at these Reynolds numbers, which are past the point of expected transition from laminar to turbulent flow. The position of maximum thickness (at 34 % of the body length measured from the tip of the nose) was more anterior than for a 'laminar' profile, supporting the idea that there is little laminar flow. The Steller sea lions in our study were characterized by a mean fineness ratio of 5.55. Their streamlined shape helps to delay flow separation, reducing total drag. In addition, turbulent boundary layers are more stable than laminar ones. Thus, separation should occur further back on the animal. Steller sea lions are the largest of the otariids and swam faster than the smaller California sea lions (Zalophus californianus). The mean glide velocity of the individual Steller sea lions ranged from 2.9 to 3.4 m s(-)(1) or 1.2-1.5 body lengths s(-)(1). These length-specific speeds are close to the optimum swim velocity of 1.4 body lengths s(-)(1) based on the minimum cost of transport for California sea lions.
Publication Date
6-15-2000
Document Type
Article
Department, Program, or Center
Thomas H. Gosnell School of Life Sciences (COS)
Recommended Citation
The Journal of Experimental Biology 203N12 (2000) 1915-1923
Campus
RIT – Main Campus
Comments
Article may be found at: http://jeb.biologists.org/cgi/reprint/203/12/1915 This work was funded by grants to the North Pacific Universities Marine Mammal Research Consortium from the North Pacific Marine Science Foundation (A.W.T.) and a grant from the Natural Science and Engineering Research Council of Canada (R.W.B.).ISSN:1477-9145 Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.