Alopias is a group of lamniform sharks characterized by a highly elongate caudal fin with three known extant species: Alopias pelagicus (pelagic thresher shark), Alopias superciliosus (bigeye thresher shark), and Alopias vulpinus (common thresher shark). Alopias pelagicus and A. vulpinus are considered fast swimmers and use their caudal fin to hunt for small schooling fish by stunning them, but this feeding behavior has never been directly observed for A. superciliosus. In this study, we examined four integumentary variables of selected fast swimming (e.g. A. pelagicus, A. vulpinus, and Lamna) and slow swimming (e.g. Mitsukurina and Megachasma) lamniform sharks to determine whether A. superciliosus is a fast swimmer or a slow swimmer. Our data indicate that A. superciliosus is a slow swimming lamniform, but it probably employs a simple laterally directed tail slap to capture its prey. Overall, our study points to an interpretation that A. superciliosus is an ambush predator, rather than an active prey-pursuing hunter. Mapping of scale data onto previously published phylogenetic trees indicate that slow swimming is a plesiomorphic condition in the order Lamniformes. Our work represents the most extensive comparative study of the morphology and variation of integumentary structures, especially placoid scales, conducted so far for Lamniformes.

中文翻译：

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基于外皮对大眼长尾鲨 Alopias superciliosus (Lamniformes: Alopiidae) 游泳能力和猎物狩猎策略的推断

Alopias 是一组以高度细长的尾鳍为特征的板状鲨鱼，已知现存的三种物种是：Alopias pelagicus（远洋长尾鲨）、Alopias superciliosus（大眼长尾鲨）和 Alopias vulpinus（普通长尾鲨）。Alopias pelagicus 和 A. vulpinus 被认为是快速游泳者，并使用它们的尾鳍通过击晕它们来捕食小型鱼群，但从未直接观察到 A. superciliosus 的这种摄食行为。在这项研究中，我们检查了选定的快速游泳（例如 A. pelagicus、A. vulpinus 和 Lamna）和慢速游泳（例如 Mitsukurina 和 Megachasma）层状鲨鱼的四个外皮变量，以确定 A. superciliosus 是快速游泳者还是缓慢游泳者游泳者。我们的数据表明 A. superciliosus 是一种缓慢游泳的板状体，但它可能采用简单的横向尾拍来捕捉猎物。总的来说，我们的研究指出了一种解释，即 A. superciliosus 是一种伏击捕食者，而不是一个活跃的猎物猎人。将尺度数据映射到先前发表的系统发育树上表明，缓慢游泳是 Lamniformes 目中的一种拟态条件。我们的工作代表了迄今为止对 Lamniformes 进行的外皮结构形态和变化的最广泛比较研究，尤其是盾状鳞片。将尺度数据映射到先前发表的系统发育树上表明，缓慢游泳是 Lamniformes 目中的一种拟态条件。我们的工作代表了迄今为止对 Lamniformes 进行的外皮结构形态和变化的最广泛比较研究，尤其是盾状鳞片。将尺度数据映射到先前发表的系统发育树上表明，缓慢游泳是 Lamniformes 目中的一种拟态条件。我们的工作代表了迄今为止对 Lamniformes 进行的外皮结构的形态和变化的最广泛的比较研究，尤其是盾状鳞片。