Shark skin is predominantly specialized for swimming and protection, with the dermal denticle being the main structure associated with these abilities. The dermal denticle is a mineral structure with a unique morphology for each species, which allows its use as a taxonomic tool. Few studies have investigated the microscopy aspects of skin and dermal denticles, considering the high diversity of sharks. Here, we investigated the three-dimensional morphoquantitative aspects and mineral composition of dermal denticles in different regions of the angular angel shark, Squatina guggenheim, using scanning electron microscopy and dispersive energy system. With the microscopy, we were able to observe that the dermal denticle morphology changes according to the area it is located. It was possible to describe the dermal denticles individually, from root to the crown, highlighting all of their individualities. Through the dispersive energy system, we showed the proportions of each mineral found in the denticle, by area, demonstrating the composition and the particularities of crown, body, and root, where whitlockite was described for the first time in elasmobranchs. In this way, the present study presented the specificities of the dermal denticles of S. guggenheim, as well sought to understand the different structure functions for the animal, thus assisting future research in animal morphology.

中文翻译：

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角鲨（Squatina guggenheim）真皮小齿的生态形态、空间和矿物关系

鲨鱼皮主要用于游泳和保护，真皮小齿是与这些能力相关的主要结构。真皮小齿是一种矿物结构，每个物种都具有独特的形态，因此可以用作分类工具。考虑到鲨鱼的高度多样性，很少有研究调查皮肤和真皮细齿的显微镜方面。在这里，我们研究了角天使鲨Squatina guggenheim 不同区域真皮小齿的三维形态定量方面和矿物质组成，使用扫描电子显微镜和色散能量系统。通过显微镜，我们能够观察到真皮小齿形态根据其所在区域而变化。可以单独描述真皮小齿，从根到冠，突出它们的所有个性。通过分散能量系统，我们按面积显示了在细齿中发现的每种矿物质的比例，展示了冠、体和根的组成和特殊性，其中首次在弹鳃中描述了白铁矿。通过这种方式，本研究展示了S真皮细齿的特异性。古根海姆，以及试图了解动物的不同结构功能，从而协助未来的动物形态研究。