Structural adaptations for ram ventilation: Gill fusions in scombrids and billfishes

TitleStructural adaptations for ram ventilation: Gill fusions in scombrids and billfishes
Publication TypeJournal Article
Year of Publication2013
AuthorsWegner NC, Sepulveda CA, Aalbers SA, Graham JB
JournalJournal of Morphology
Date Published2013/01
Type of ArticleArticle
ISBN Number0362-2525
Accession NumberWOS:000312249300009
Keywordsage; bass; bluefish pomatomus-saltatrix; growth; morone-saxatilis; oceanic fishes; performance; pherson gr, 1992, australian journal of marine and freshwater research, v43, p1269; scomberomorus; skipjack tuna; swimming energetics; tuna katsuwonus-pelamis; tuna, mackerel, marlin, swordfish, gill filament, gill lamellae

For ram-gill ventilators such as tunas and mackerels (family Scombridae) and billfishes (families Istiophoridae, Xiphiidae), fusions binding the gill lamellae and filaments prevent gill deformation by a fast and continuous ventilatory stream. This study examines the gills from 28 scombrid and seven billfish species in order to determine how factors such as body size, swimming speed, and the degree of dependence upon ram ventilation influence the site of occurrence and type of fusions. In the family Scombridae there is a progressive increase in the reliance on ram ventilation that correlates with the elaboration of gill fusions. This ranges from mackerels (tribe Scombrini), which only utilize ram ventilation at fast cruising speeds and lack gill fusions, to tunas (tribe Thunnini) of the genus Thunnus, which are obligate ram ventilators and have two distinct fusion types (one binding the gill lamellae and a second connecting the gill filaments). The billfishes appear to have independently evolved gill fusions that rival those of tunas in terms of structural complexity. Examination of a wide range of body sizes for some scombrids and billfishes shows that gill fusions begin to develop at lengths as small as 2.0 cm fork length. In addition to securing the spatial configuration of the gill sieve, gill fusions also appear to increase branchial resistance to slow the high-speed current produced by ram ventilation to distribute flow evenly and optimally to the respiratory exchange surfaces. J. Morphol. 2013. (c) 2012 Wiley Periodicals, Inc.

Short TitleJ. Morphol.
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