Feeding of the Megamouth Shark (Pisces: Lamniformes: Megachasmidae) Predicted by Its Hyoid Arch: A Biomechanical Approach
Feeding of the Megamouth Shark (Pisces: Lamniformes: Megachasmidae) Predicted by Its Hyoid Arch: A Biomechanical Approach
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DOI：
10.1002/jmor.10905
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发表时间：
2011-05-01
影响因子：
1.5
通讯作者：
Nakaya, Kazuhiro
中科院分区：
文献类型：
--
作者：
Tomita, Taketeru;Sato, Keiichi;Nakaya, Kazuhiro
对巨嘴鲨的研究可以提供关于它们进化史的信息。巨嘴鲨是三种食浮游鲨鱼之一。在活体动物中从未观察到巨嘴鲨的进食，但生物力学的两种替代假说认为，要么进食，即公羊进食，要么吸入进食。在这项研究中，使用计算机断层摄影术计算了21种公羊和吸食鲨鱼的角软骨面积的二阶矩，它是软骨弯曲硬度的一个指标。结果表明，吸食性鲨鱼的颈椎软骨比公羊食性鲨鱼具有更大的第二矩面积。结果还表明，反映公羊相对贡献和吸力行为的公羊吸力指数也与颈椎面积的二阶矩相关。考虑到吸食性鲨鱼在吸食过程中可能会受到较大的弯曲应力，吸食性鲨鱼的吸食性软骨面积的较大二阶矩可以解释为对吸食性摄食的适应。根据巨嘴鲨的颈椎软骨面积的小二阶矩，认为巨嘴鲨的摄食方式类似于食浮性晒鲨的公羊摄食方式。根据这些结果，可以提出三种食浮性鲨鱼的取食机制的进化情景。在这种情况下，食浮性鲸鲨是从吸食底栖生物的祖先进化而来的。捕食浮游性巨嘴鲨和晒鲨的公羊是从公羊捕食游泳型祖先进化而来的，它们都发展了自己独特的过滤系统来捕获小型猎物。J.Morphol。2011年，272：513-524。(C)2011年Wiley-Liss，Inc.
Studies of the megamouth shark, one of three planktivorous sharks, can provide information about their evolutionary history. Megamouth shark feeding has never been observed in life animals, but two alternative hypotheses on biomechanics suggest either feeding, i.e., ram feeding or suction feeding. In this study, the second moment of area of the ceratohyal cartilages, which is an indicator of the flexural stiffness of the cartilages, is calculated for 21 species of ram-and suction-feeding sharks using computed tomography. The results indicate that suction-feeding sharks have ceratohyal cartilages with a larger second moment of area than ram-feeding sharks. The result also indicates that the ram-suction index, which is an indicator of relative contribution of ram and suction behavior, is also correlated with the second moment of area of the ceratohyal. Considering that large bending stresses are expected to be applied to the ceratohyal cartilage during suction, the larger second moment of area of the ceratohyal of suction-feeding sharks can be interpreted as an adaptation for suction feeding. Based on the small second moment of area of the ceratohyal cartilage of the megamouth shark, the feeding mode of the megamouth shark is considered to be ram feeding, similar to the planktivorous basking shark. From these results, an evolutionary scenario of feeding mechanics of three species of planktivorous sharks can be suggested. In this scenario, the planktivorous whale shark evolved ram feeding from a benthic suction-feeding ancestor. Ram feeding in the planktivorous megamouth shark and the basking shark evolved from ram feeding swimming-type ancestors and that both developed their unique filtering system to capture small-sized prey. J. Morphol. 272:513-524, 2011. (C) 2011 Wiley-Liss, Inc.