Hydrodynamic role of longitudinal dorsal ridges in a leatherback turtle swimming.
Leatherback sea turtles (Dermochelys coriacea) are known to have a superior diving ability and be highly adapted to pelagic swimming. They have five longitudinal ridges on their carapace. Although it was conjectured that these ridges might be an adaptation for flow control, no rigorous study has been performed to understand their hydrodynamic roles. Here we show that these ridges are slightly misaligned to the streamlines around the body to generate streamwise vortices, and suppress or delay flow separation on the carapace, resulting in enhanced hydrodynamic performances during different modes of swimming. Our results suggest that shapes of some morphological features of living creatures, like the longitudinal ridges of the leatherback turtles, need not be streamlined for excellent hydro- or aerodynamic performances, contrary to our common physical intuition.
Department of Mechanical &Aerospace Engineering, Seoul National University, Seoul, Korea.
Kyeongtae
K
Bang
School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology, Ulsan, Korea.
Jooha
J
Kim
Institute of Advanced Machines and Design, Seoul National University, Seoul, Korea.|Laboratory of Behavioral Ecology and Evolution, School of Biological Sciences, Seoul National University, Seoul, Korea.
Sang-Im
SI
Lee
Department of Mechanical &Aerospace Engineering, Seoul National University, Seoul, Korea.|Institute of Advanced Machines and Design, Seoul National University, Seoul, Korea.
Haecheon
H
Choi
D000222:Adaptation, Physiological; D060105:Animal Shells / Q000033:anatomy & histology*; D000818:Animals; D057446:Hydrodynamics; D013550:Swimming; D014426:Turtles / Q000502:physiology*
Philos Trans R Soc Lond B Biol Sci. 2007 Nov 29;362(1487):2141-50
17472919
J Exp Biol. 2010 Dec 1;213(Pt 23):4074-83
21075949
J Exp Biol. 1976 Feb;64(1):1-12
1270983
J Exp Biol. 2003 Feb;206(Pt 4):725-44
12517990
J Exp Biol. 2002 Dec;205(Pt 23):3689-97
12409495
Sci Rep. 2015 May 07;5:9914
25951056
Integr Comp Biol. 2002 Nov;42(5):971-80
21680378
Nature. 2004 Jun 3;429(6991):522
15175742
Bioinspir Biomim. 2008 Mar;3:014001
18364559
Nature. 2011 Jun 22;475(7354):86-90
21697831
J Exp Biol. 1998 Sep;201 (Pt 17):2497-505
9698584
J Exp Biol. 2010 Dec 1;213(Pt 23):3961-71
21075937