Scaling of swimming performance in baleen whales
Abstract
The scale-dependence of locomotor factors have long been studied in comparative biomechanics, but remain 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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 01, 2019
- Source ID
- 10.1242/jeb.204172
Entities
People
- Ari S. Friedlaender
- David E. Cade
- David N Wiley
- David W Johnston
- Fleur Visser
- Frank E Fish
- Gwenith Penry
- Jacopo Di Clemente
- Jean Potvin
- Jeremy A. Goldbogen
- John H. Long
- John Kennedy
- Julian Dale
- K C Bierlich
- Machiel G. Oudejans
- Malene Simon
- Matthew Savoca
- Paolo S Segre
- Shirel R. Kahane-Rapport
- Simone K A Videsen
- William Gough
Organizations
- Aarhus University
- Duke University
- Greenland Institute of Natural Resources
- National Oceanic and Atmospheric Administration
- National Science Foundation
- Nelson Mandela University
- Office of Naval Research
- Royal Netherlands Institute of Sea Research
- Saint Louis University
- Stanford University
- Stanford University School of Humanities and Sciences
- University of Amsterdam
- University of California
- Vassar College
- West Chester University of Pennsylvania