“巨骨舌鱼”（亚马逊流域一种淡水鱼）的鱼鳞内的盘状结构的排列，是其能够保护自己不被“水虎鱼（食人鱼）”咬伤的关键。这一发现发表在本期Nature Communications上。
人们知道，“水虎鱼（食人鱼）”是可怕的攻击者，它们的利齿能夹住猎物，使其丧失能力。某些鱼类进化出了能够避免这种攻击造成死亡的能力：有些形成了能够更快游动的能力，而其他的则长出了坚硬的自然盔甲（以保护性鱼鳞形式存在），后者能吸收咬噬牙齿的撞击力。Robert Ritchie和他的研究小组发现，“巨骨舌鱼”鱼鳞中名为“薄片”（lamellae）的盘状结构的分布使这种鱼能吸收来自一个所施加负荷的能量。他们发现，这种鱼是通过改变“水虎鱼”牙齿所施加高压力的方向、扭转这种压力、并有可能减轻这种压力以及防止自己的鳞片被压碎来做到这一点的。作者得出的结论是，外层“薄片”使鱼鳞具有硬度和抗穿透力，而鱼鳞和“薄片”的波纹状外表面的重叠则使鱼鳞能够以这种方式弯曲，将拉张应力转移给内层的、下层的鱼鳞。（生物谷Bioon.com）
生物谷推荐的英文摘要
Nature Communications doi:10.1038/ncomms3634
Mechanical adaptability of the Bouligand-type structure in natural dermal armour
Elizabeth A. Zimmermann，Bernd Gludovatz，Eric Schaible，Neil K. N. Dave，Wen Yang，Marc A. Meyers& Robert O. Ritchie
Arapaima gigas， a fresh water fish found in the Amazon Basin， resist predation by piranhas through the strength and toughness of their scales， which act as natural dermal armour. Arapaima scales consist of a hard， mineralized outer shell surrounding a more ductile core. This core region is composed of aligned mineralized collagen fibrils arranged in distinct lamellae. Here we show how the Bouligand-type (twisted plywood) arrangement of collagen fibril lamellae has a key role in developing their unique protective properties， by using in situ synchrotron small-angle X-ray scattering during mechanical tensile tests to observe deformation mechanisms in the fibrils. Specifically， the Bouligand-type structure allows the lamellae to reorient in response to the loading environment； remarkably， most lamellae reorient towards the tensile axis and deform in tension through stretching/sliding mechanisms， whereas other lamellae sympathetically rotate away from the tensile axis and compress， thereby enhancing the scale’s ductility and toughness to prevent fracture.
