Wegner Nicholas C, Sepulveda Chugey A, Aalbers Scott A, Graham Jeffrey B
Center for Marine Biotechnology and Biomedicine, Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093, USA.
J Morphol. 2013 Jan;274(1):108-20. doi: 10.1002/jmor.20082. Epub 2012 Sep 29.
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.
对于金枪鱼和鲭鱼（鲭科）以及旗鱼（旗鱼科、剑鱼科）等冲压式鳃呼吸器而言，连接鳃小片和鳃丝的融合结构可防止鳃在快速持续的通气水流作用下发生变形。本研究检查了28种鲭科鱼类和7种旗鱼的鳃，以确定诸如体型、游泳速度以及对冲压式通气的依赖程度等因素如何影响融合结构的出现部位和类型。在鲭科中，对冲压式通气的依赖程度逐渐增加，这与鳃融合结构的精细程度相关。范围从鲭鱼（鲭属），它们仅在快速巡航速度时利用冲压式通气且缺乏鳃融合结构，到金枪鱼属（金枪鱼族）的金枪鱼，它们是专性冲压式呼吸器且有两种不同的融合类型（一种连接鳃小片，另一种连接鳃丝）。旗鱼似乎独立进化出了在结构复杂性上可与金枪鱼相媲美的鳃融合结构。对一些鲭科鱼类和旗鱼的多种体型进行检查表明，鳃融合结构在叉长小至2.0厘米时就开始发育。除了确保鳃筛的空间构型外，鳃融合结构似乎还会增加鳃的阻力，以减缓冲压式通气产生的高速水流，从而将水流均匀且最佳地分配到呼吸交换表面。
