Gill morphometrics of the thresher sharks (genus alopias): Correlation of gill dimensions with aerobic demand and environmental oxygen

TitleGill morphometrics of the thresher sharks (genus alopias): Correlation of gill dimensions with aerobic demand and environmental oxygen
Publication TypeJournal Article
Year of Publication2015
AuthorsWootton T.P, Sepulveda CA, Wegner NC
JournalJournal of Morphology
Volume276
Pagination589-600
Date Published2015/05
Type of ArticleArticle
ISBN Number0362-2525
Accession NumberWOS:000353234000010
Keywordsaerobic metabolism; diffusion capacity; elasmobranch; elasmobranch fishes; endothermy; fish gills; gill surface area; hypoxia; isurus-oxyrinchus; lamnid shark; minimum zone; morphology; pacific-ocean; ram; regional; shortfin mako; superciliosus; ventilation
Abstract

Gill morphometrics of the three thresher shark species (genus Alopias) were determined to examine how metabolism and habitat correlate with respiratory specialization for increased gas exchange. Thresher sharks have large gill surface areas, short water-blood barrier distances, and thin lamellae. Their large gill areas are derived from long total filament lengths and large lamellae, a morphometric configuration documented for other active elasmobranchs (i.e., lamnid sharks, Lamnidae) that augments respiratory surface area while limiting increases in branchial resistance to ventilatory flow. The bigeye thresher, Alopias superciliosus, which can experience prolonged exposure to hypoxia during diel vertical migrations, has the largest gill surface area documented for any elasmobranch species studied to date. The pelagic thresher shark, A. pelagicus, a warm-water epi-pelagic species, has a gill surface area comparable to that of the common thresher shark, A. vulpinus, despite the latter's expected higher aerobic requirements associated with regional endothermy. In addition, A. vulpinus has a significantly longer water-blood barrier distance than A. pelagicus and A. superciliosus, which likely reflects its cold, well-oxygenated habitat relative to the two other Alopias species. In fast-swimming fishes (such as A. vulpinus and A. pelagicus) cranial streamlining may impose morphological constraints on gill size. However, such constraints may be relaxed in hypoxia-dwelling species (such as A. superciliosus) that are likely less dependent on streamlining and can therefore accommodate larger branchial chambers and gills. J. Morphol. 276:589-600, 2015. (c) 2015 Wiley Periodicals, Inc.

DOI10.1002/jmor.20369
Short TitleJ. Morphol.
Student Publication: 
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