Maie Takashi, Schoenfuss Heiko L, Blob Richard W
Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA.
J Morphol. 2013 Jul;274(7):733-42. doi: 10.1002/jmor.20130. Epub 2013 Feb 28.
Gobiid fishes possess a distinctive ventral sucker, formed from fusion of the pelvic fins. This sucker is used to adhere to a wide range of substrates including, in some species, the vertical cliffs of waterfalls that are climbed during upstream migrations. Previous studies of waterfall-climbing goby species have found that pressure differentials and adhesive forces generated by the sucker increase with positive allometry as fish grow in size, despite isometry or negative allometry of sucker area. To produce such scaling patterns for pressure differential and adhesive force, waterfall-climbing gobies might exhibit allometry for other muscular or skeletal components of the pelvic sucker that contribute to its adhesive function. In this study, we used anatomical dissections and modeling to evaluate the potential for allometric growth in the cross-sectional area, effective mechanical advantage (EMA), and force generating capacity of major protractor and retractor muscles of the pelvic sucker (m. protractor ischii and m. retractor ischii) that help to expand the sealed volume of the sucker to produce pressure differentials and adhesive force. We compared patterns for three Hawaiian gobiid species: a nonclimber (Stenogobius hawaiiensis), an ontogenetically limited climber (Awaous guamensis), and a proficient climber (Sicyopterus stimpsoni). Scaling patterns were relatively similar for all three species, typically exhibiting isometric or negatively allometric scaling for the muscles and lever systems examined. Although these scaling patterns do not help to explain the positive allometry of pressure differentials and adhesive force as climbing gobies grow, the best climber among the species we compared, S. stimpsoni, does exhibit the highest calculated estimates of EMA, muscular input force, and output force for pelvic sucker retraction at any body size, potentially facilitating its adhesive ability.
虾虎鱼具有独特的腹吸盘，由腹鳍融合形成。这个吸盘用于附着在多种基质上，在某些物种中，包括在溯河洄游期间攀爬的瀑布垂直峭壁上。先前对攀爬瀑布的虾虎鱼物种的研究发现，尽管吸盘面积呈等比例或负异速生长，但随着鱼体长大，吸盘产生的压力差和粘附力会随着正异速生长而增加。为了产生这种压力差和粘附力的缩放模式，攀爬瀑布的虾虎鱼可能在腹吸盘的其他肌肉或骨骼成分上表现出异速生长，这些成分有助于其粘附功能。在本研究中，我们使用解剖学解剖和建模来评估腹吸盘主要前拉肌和后拉肌（坐骨前拉肌和坐骨后拉肌）的横截面积、有效机械优势（EMA）和力产生能力的异速生长潜力，这些肌肉有助于扩大吸盘的密封体积以产生压力差和粘附力。我们比较了三种夏威夷虾虎鱼的模式：一种非攀爬者（夏威夷窄颅虾虎鱼）、一种个体发育受限的攀爬者（关岛阿胡虾虎鱼）和一种熟练的攀爬者（斯氏弹涂鱼）。所有三个物种的缩放模式相对相似，通常在所检查的肌肉和杠杆系统中表现出等比例或负异速缩放。尽管这些缩放模式无助于解释随着攀爬虾虎鱼长大压力差和粘附力的正异速生长，但在我们比较的物种中，最佳攀爬者斯氏弹涂鱼在任何体长下，其腹吸盘后缩的EMA、肌肉输入力和输出力的计算估计值确实最高，这可能有助于其粘附能力。
