Neutral buoyancy is optimal to minimize the cost of transport in horizontally swimming seals

• Published in: Scientific Reports
• Main Authors: Sato, Katsufumi, Aoki, Kagari, Watanabe, Yuuki Y., Miller, Patrick J. O.
• Other Authors: NERC, University of St Andrews. School of Biology, University of St Andrews. Marine Alliance for Science & Technology Scotland, University of St Andrews. Scottish Oceans Institute, University of St Andrews. Institute of Behavioural and Neural Sciences, University of St Andrews. Centre for Social Learning & Cognitive Evolution, University of St Andrews. Bioacoustics group, University of St Andrews. Sea Mammal Research Unit
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2014
• Subjects: Energetic advantages; Stroking patterns; Elephant seals; Body density; Fish; Whales; Depth; Sink; QL Zoology; QL; Elephant Seals
• Online Access: http://hdl.handle.net/10023/5009; https://doi.org/10.1038/srep02205

This study was supported by National Environment Research Council grant NERC NE/c00311X/1, a Grant-in-Aid for Science Research from the Japan Society for the Promotion of Science (to K.S. and Y.Y.W.), a grant from Canon Foundation and program Bio-Logging Science of the University of Tokyo (UTBLS). Flying and terrestrial animals should spend energy to move while supporting their weight against gravity. On the other hand, supported by buoyancy, aquatic animals can minimize the energy cost for supporting their body weight and neutral buoyancy has been considered advantageous for aquatic animals. However, some studies suggested that aquatic animals might use non-neutral buoyancy for gliding and thereby save energy cost for locomotion. We manipulated the body density of seals using detachable weights and floats, and compared stroke efforts of horizontally swimming seals under natural conditions using animal-borne recorders. The results indicated that seals had smaller stroke efforts to swim a given speed when they were closer to neutral buoyancy. We conclude that neutral buoyancy is likely the best body density to minimize the cost of transport in horizontal swimming by seals. Publisher PDF Peer reviewed