Crystal architecture of the tooth and jaw bone (pyramid) of the sea urchin Paracentrotus lividus
Crystal architecture of the tooth and jaw bone (pyramid) of the sea urchin Paracentrotus lividus
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DOI：
10.1680/bbn.11.00018
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发表时间：
2012-01-01
影响因子：
--
通讯作者：
Schmahl, W. W.
中科院分区：
文献类型：
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作者：
Griesshaber, E.;Goetz, A. J.;Schmahl, W. W.
海胆用牙齿从岩石上磨掉藻类。由于方解石是一种软而脆的材料，因此这种材料的结构如何适合牙齿是很有趣的。的牙齿和颌骨（金字塔）的海胆Paracentrotus lividus的晶体结构确定的电子背散射衍射，显微断层扫描，扫描电子显微镜。海胆牙齿是低和高镁方解石混合复合材料，形成一个层次的多重复合晶体。牙齿结构由轻微（3度-5度）取向错误的主要结构单元组成，每个结构单元由亚单元组装而成，亚单元相对于彼此再次取向错误1度-2度。牙齿的整个长度都有系统性的方向错误。颌骨（金字塔）由大的多孔单晶体组成。牙齿的多重结构结合了不同大小、形状、成分和晶体学取向的方解石成分，以提供功能机制。中心的“石头”部分是最硬的，形成了切割尖端。它被包裹在较软的“板”和“层状针复合体”单元中，这些单元在石头中相互交错。通过削掉“板”和“薄片/针”，可实现齿的连续自锐。“类似单晶的质地保证了恒定的自锐机制。
Sea urchins use their teeth to grind off algae from rocks. Since calcite is a soft and brittle material, it is intriguing how this material is structured to be suitable for a tooth. The crystallographic architecture of the tooth and the jaw bone (pyramid) of the sea urchin Paracentrotus lividus was determined by electron backscatter diffraction, microtomography, and scanning electron microscopy. Sea urchin teeth are low and high Mg-calcite hybrid composites that form a hierarchical multiplex composite crystal. The tooth architecture consists of the slightly (3 degrees-5 degrees) misoriented major structural units, each of which is assembled of subunits, which are again misoriented by 1 degrees-2 degrees relative to each other. The misorientation is systematic throughout the entire length of the tooth. The jaw bones (pyramids) are composed of large porous single-crystal units. The multiplex architecture of the tooth combines calcite components of different sizes, shapes, compositions and crystallographic orientation to provide a functional mechanism. The central "stone" part is hardest and forms the cutting tip. It is encased in the softer "plates" and "lamellar needle complex" units which interdigitate in the stone. Continuous self-sharpening of the tooth occurs by chipping off the "plates" and "lamellae/needles." The single-crystal-like texture guarantees a constant mechanism of self-sharpening.