Dorsal and anal fin function in bluegill sunfish Lepomis macrochirus: three-dimensional kinematics during propulsion and maneuvering
Dorsal and anal fin function in bluegill sunfish Lepomis macrochirus: three-dimensional kinematics during propulsion and maneuvering
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DOI：
10.1242/jeb.01706
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发表时间：
2005-07
影响因子：
2.8
通讯作者：
E. Standen;G. Lauder
中科院分区：
文献类型：
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作者：
E. Standen;G. Lauder
背鳍和臀鳍是位于鱼类质心上方和下方的中间鳍，每条鳍都有一个相对于纵轴的力矩臂。了解背鳍和肛鳍的运动学可能会阐明这些鳍是如何协同使用来保持和改变鱼的身体位置的，但人们对这些鳍的功能知之甚少。利用3台同步高速摄像机(500帧S-1)，研究了定常游泳(0.5~2.5TL S-1)和低速动作(0.5TL S-1)时背鳍和肛鳍的三维运动学。通过对鳍片软线部分中每隔一条鳍线上的点进行数字化处理，我们不仅能够确定鳍片表面的运动，而且还能确定单个鳍片射线的曲率和由此产生的鳍片表面形状。我们发现，背鳍和肛鳍在超过1.0TL S-1的稳定游泳速度下开始同步振荡，尾鳍的最大横向位移和鳍面积随着稳定游泳速度的增加而增加。背鳍和肛鳍在面积、侧向位移和力矩臂上的差异表明，背鳍和肛鳍在稳定的游泳过程中会产生平衡力矩。在动作过程中，鳍面积最大，两个鳍的平均横向漂移均大于稳态游时，且各动作之间的变化较大。在机动过程中，鳍面形状发生了剧烈的变化。在任何给定的时间点，沿着鳍射线的跨向(底部到尖端)的曲率在相邻的射线之间可能不同，这表明鱼对鳍面形状有很高的控制水平。此外，在演习中，背鳍和肛鳍的整个表面都可以弯曲，而不会有单独的鳍射线显示明显的曲率。
SUMMARY Dorsal and anal fins are median fins located above and below the centre of mass of fishes, each having a moment arm relative to the longitudinal axis. Understanding the kinematics of dorsal and anal fins may elucidate how these fins are used in concert to maintain and change fish body position and yet little is known about the functions of these fins. Using three synchronized high-speed cameras (500 frames s–1) we studied the three-dimensional kinematics of dorsal and anal fins during steady swimming (0.5–2.5 TL s–1, where TL=total length) and during slow speed maneuvers (0.5 TL s–1). By digitizing points along every other fin ray in the soft-rayed portion of the fins we were able to determine not only the movement of the fin surface but also the curvature of individual fin rays and the resulting fin surface shape. We found that dorsal and anal fins begin oscillating, in phase, at steady swimming speeds above 1.0 TL s–1 and that maximum lateral displacement of the trailing edge of the fins as well as fin area increase with increasing steady swimming speed. Differences in area, lateral displacement and moment arm between the dorsal and anal fin suggest that dorsal and anal fins produce balancing torques during steady swimming. During maneuvers, fin area is maximized and mean lateral excursion of both fins is greater than during steady swimming, with large variation among maneuvers. Fin surface shape changes dramatically during maneuvers. At any given point in time the spanwise (base to tip) curvature along fin rays can differ between adjacent rays, suggesting that fish have a high level of control over fin surface shape. Also, during maneuvers the whole surface of both dorsal and anal fins can be bent without individual fin rays exhibiting significant curvature.