Buoyancy and maximal diving depth in penguins

• Published in: Journal of Experimental Biology
• Main Authors: Sato, Katsufumi, Naito, Y., Kato, A., Niizuma, Y., Watanuki, Y., Charrassin, Jean-Benoit, Bost, Charles-André, Handrich, Y., Le Maho, Y.
• Other Authors: National Institute of Polar Research Tokyo (NiPR), Hokkaido Information University, Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Centre d'écologie et physiologie énergétiques (CEPE), Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2002
• Subjects: [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph]; King Penguins
• Online Access: https://hal.science/hal-03692397; https://doi.org/10.1242/jeb.205.9.1189

International audience SUMMARY Using a newly developed data logger to measure acceleration, we demonstrate that free-ranging king and Adélie penguins only beat their flippers substantially during the first part of descent or when they were presumed to be chasing prey at the bottom of dives. Flipper beating stopped during the latter part of ascent: at 29±9 % (mean ± S.D.) of dive depth(mean dive depth=136.8±145.1 m, N=425 dives) in king penguins,and at 52±20 % of dive depth (mean dive depth=72.9±70.5 m, N=664 dives) in Adélie penguins. Propulsive swim speeds of both species were approximately 2 m s-1 during dives; however, a marked increase in speed, up to approximately 2.9 m s-1, sometimes occurred in king penguins during the passive ascending periods. During the prolonged ascending, oblique ascent angle and slowdown near the surface may represent one way to avoid the potential risk of decompression sickness. Biomechanical calculations for data from free-ranging king and Adélie penguins indicate that the air volume of the birds (respiratory system and plumage) can provide enough buoyancy for the passive ascent. When comparing the passive ascents for shallow and deep dives, there is a positive correlation between air volume and the depth of the dive. This suggests that penguins regulate their air volume to optimize the costs and benefits of buoyancy.