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Fur seals do, but sea lions don't — cross taxa insights into exhalation during ascent from dives
journal contribution
posted on 2021-08-02, 00:00 authored by Sascha K Hooker, Russel D Andrews, John ArnouldJohn Arnould, Marthán N Bester, Randall W Davis, Stephen J Insley, Nick J Gales, Simon D Goldsworthy, J Chris McKnightManagement of gases during diving is not well understood across marine mammal species. Prior to diving, phocid (true) seals generally exhale, a behaviour thought to assist with the prevention of decompression sickness. Otariid seals (fur seals and sea lions) have a greater reliance on their lung oxygen stores, and inhale prior to diving. One otariid, the Antarctic fur seal (Arctocephalus gazella), then exhales during the final 50–85% of the return to the surface, which may prevent another gas management issue: shallow-water blackout. Here, we compare data collected from animal-attached tags (video cameras, hydrophones and conductivity sensors) deployed on a suite of otariid seal species to examine the ubiquity of ascent exhalations for this group. We find evidence for ascent exhalations across four fur seal species, but that such exhalations are absent for three sea lion species. Fur seals and sea lions are no longer genetically separated into distinct subfamilies, but are morphologically distinguished by the thick underfur layer of fur seals. Together with their smaller size and energetic dives, we suggest their air-filled fur might underlie the need to perform these exhalations, although whether to reduce buoyancy and ascent speed, for the avoidance of shallow-water blackout or to prevent other cardiovascular management issues in their diving remains unclear. This article is part of the theme issue ‘Measuring physiology in free-living animals (Part I)’.
History
Journal
Philosophical transactions of the Royal Society B: biological sciencesVolume
376Issue
1830Article number
20200219Pagination
1 - 11Publisher
Royal SocietyLocation
London, Eng.Publisher DOI
ISSN
0962-8436eISSN
1471-2970Language
engPublication classification
C Journal article; C1 Refereed article in a scholarly journalUsage metrics
Keywords
diving physiologygas managementotariidshallow-water blackoutScience & TechnologyLife Sciences & BiomedicineBiologyLife Sciences & Biomedicine - Other TopicsALVEOLAR GAS-EXCHANGEFLIPPER STROKE RATEDIVING BEHAVIORFORAGING BEHAVIORMAMMALIAN INSULATIONTHERMAL-PROPERTIESHEART-RATENORTHERNPHYSIOLOGYLIMITEvolutionary Biology
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