School of Earth and Environment, University of Leeds, Leeds, West Yorkshire LS2 9JT, UK
School of Biology, University of Leeds, Leeds, West Yorkshire LS2 9JT, UK.
Proc Biol Sci. 2014 Aug 7;281(1788):20140703. doi: 10.1098/rspb.2014.0703.
From their earliest origins, fishes have developed a suite of adaptations for locomotion in water, which determine performance and ultimately fitness. Even without data from behaviour, soft tissue and extant relatives, it is possible to infer a wealth of palaeobiological and palaeoecological information. As in extant species, aspects of gross morphology such as streamlining, fin position and tail type are optimized even in the earliest fishes, indicating similar life strategies have been present throughout their evolutionary history. As hydrodynamical studies become more sophisticated, increasingly complex fluid movement can be modelled, including vortex formation and boundary layer control. Drag-reducing riblets ornamenting the scales of fast-moving sharks have been subjected to particularly intense research, but this has not been extended to extinct forms. Riblets are a convergent adaptation seen in many Palaeozoic fishes, and probably served a similar hydrodynamic purpose. Conversely, structures which appear to increase skin friction may act as turbulisors, reducing overall drag while serving a protective function. Here, we examine the diverse adaptions that contribute to drag reduction in modern fishes and review the few attempts to elucidate the hydrodynamics of extinct forms.
从它们最早的起源开始，鱼类就已经发展出了一系列适应水中运动的特征，这些特征决定了它们的运动性能，最终影响它们的适应性。即使没有来自行为、软组织和现存亲属的数据，也有可能推断出大量的古生物学和古生态学信息。与现存物种一样，即使在最早的鱼类中，流线型、鳍的位置和尾巴类型等大体形态特征也得到了优化，这表明在它们的进化历史中，一直存在着类似的生活策略。随着水动力学研究变得更加复杂，可以对越来越复杂的流体运动进行建模，包括涡旋的形成和边界层的控制。快速游动的鲨鱼鳞片上的减阻脊纹受到了特别强烈的研究，但这并没有扩展到已灭绝的形式。脊纹是许多古生代鱼类中存在的趋同适应，可能具有类似的水动力功能。相反，那些似乎增加了皮肤摩擦力的结构可能起到了扰流板的作用，在起到保护作用的同时，减少了整体阻力。在这里，我们研究了现代鱼类中有助于减少阻力的各种适应性，并回顾了一些试图阐明已灭绝鱼类水动力的尝试。
