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J Exp Biol. 2019 Oct 23;222(Pt 20). pii: jeb204172. doi: 10.1242/jeb.204172.

Scaling of swimming performance in baleen whales.

Author information

1
Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA wgough@stanford.edu.
2
Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA.
3
Nicholas School of the Environment, Duke University, Beaufort, NC 28516, USA.
4
Department of Physics, Saint Louis University, St Louis, MO 633103, USA.
5
Department of Biology, West Chester University, West Chester, PA 19383, USA.
6
Accademia del Leviatano, Viale dell'Astronomia, 00144 Rome, Italy.
7
Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, CA 95064, USA.
8
Departments of Biology and Cognitive Science, Vassar College, Poughkeepsie, NY 12604, USA.
9
Kelp Marine Research, 1624 CJ Hoorn, The Netherlands.
10
Department of Zoology, Institute for Coastal and Marine Research, Nelson Mandela University, Port Elizabeth, 6019, South Africa.
11
Greenland Climate Research Centre, Greenland Institute of Natural Resources, Kivioq 2, 3900 Nuuk, Greenland.
12
Zoophysiology, Department of Bioscience, Faculty of Science and Technology, Aarhus University, Aarhus 8000, Denmark.
13
Institute for Biodiversity and Ecosystem Dynamics - Freshwater and Marine Ecology, University of Amsterdam, 1090 GE Amsterdam, The Netherlands.
14
Royal Netherlands Institute for Sea Research, 1790 AB Den Burg, Texel, The Netherlands.
15
US National Oceanic and Atmospheric Administration, Office of National Marine Sanctuaries, Stellwagen Bank National Marine Sanctuary, Scituate, MA 02066, USA.

Abstract

The scale dependence of locomotor factors has long been studied in comparative biomechanics, but remains poorly understood for animals at the upper extremes of body size. Rorqual baleen whales include the largest animals, but we lack basic kinematic data about their movements and behavior below the ocean surface. Here, we combined morphometrics from aerial drone photogrammetry, whale-borne inertial sensing tag data and hydrodynamic modeling to study the locomotion of five rorqual species. We quantified changes in tail oscillatory frequency and cruising speed for individual whales spanning a threefold variation in body length, corresponding to an order of magnitude variation in estimated body mass. Our results showed that oscillatory frequency decreases with body length (∝length-0.53) while cruising speed remains roughly invariant (∝length0.08) at 2 m s-1 We compared these measured results for oscillatory frequency against simplified models of an oscillating cantilever beam (∝length-1) and an optimized oscillating Strouhal vortex generator (∝length-1). The difference between our length-scaling exponent and the simplified models suggests that animals are often swimming non-optimally in order to feed or perform other routine behaviors. Cruising speed aligned more closely with an estimate of the optimal speed required to minimize the energetic cost of swimming (∝length0.07). Our results are among the first to elucidate the relationships between both oscillatory frequency and cruising speed and body size for free-swimming animals at the largest scale.

KEYWORDS:

Frequency; Hydrodynamic modeling; Locomotion; Morphometrics; Speed; Unoccupied aerial systems

PMID:
31558588
DOI:
10.1242/jeb.204172

Conflict of interest statement

Competing interestsThe authors declare no competing or financial interests.

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