The mechanism by which sea anemones attach to surfaces underwater remains elusive, which is surprising given their ubiquitous distribution in the world’s oceans and tractability for experimental biology. Their adhesion is mechanically interesting, bridging the interface between very hard and soft materials. The Cnidaria are thought to have evolved adhesion to surfaces at least 505 Ma ago implying that, among the Metazoa, only Porifera developed this capability earlier. The purpose of this study was primarily to address an existing hypothesis, that spirocysts (a sticky class of cnidocyst) facilitate adhesion to surfaces, as observed during prey capture. We demonstrated conclusively that spirocysts were not involved in the pedal disc adhesion of Exaiptasia pallida. Second, we applied a variety of imaging methods to develop an understanding of the true adhesion mechanism. Morphological studies using scanning electron microscopy identified a meshwork of adhesive material, unique to the pedal disc. Serial block-face SEM highlighted four classes of cells that could secrete the adhesive from the pedal disc ectoderm. A variety of histochemical techniques identified proteins, glycans and quinones in the cell contents and secreted adhesive, with variation in contents of specific cell-types in different areas of the body. Spirocysts are not used by Exaiptasia pallida for adhesion to surfaces. Instead, a structurally and compositionally complex secreted glue was observed, firmly attaching the animals underwater. The results of this study provide a basis for further investigations of adhesion in Cnidaria, and establish E. pallida as a new model organism for bioadhesion research.

中文翻译：

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海葵（Exaiptasia pallida）使用分泌的粘合剂和复杂的踏板形态进行表面附着。

海葵附着于水下表面的机制仍然难以捉摸，考虑到它们在世界海洋中的普遍分布以及实​​验生物学的易处理性，这令人惊讶。它们的粘合在机械上很有趣，可以将非常硬和柔软的材料之间的界面桥接起来。人们认为，刺孢至少在505 Ma之前就已经发展出对表面的附着力，这意味着在后生动物中，只有Porifera较早地开发了这种能力。这项研究的目的主要是为了解决一个现有的假设，即在捕获猎物时观察到，螺旋囊（粘性类的囊肿）有助于粘附在表面上。我们最终证明，螺旋藻不参与Exaiptasia pallida的踏板椎间盘粘连。第二，我们应用了多种成像方法来加深对真正粘连机制的理解。使用扫描电子显微镜的形态学研究确定了踏板盘特有的粘合剂材料网。连续块状SEM突出显示了四类细胞，它们可以从踏板盘外层分泌出粘合剂。多种组织化学技术可以识别细胞内蛋白质，聚糖和醌的含量，并分泌黏附剂，从而使人体不同部位特定细胞类型的含量发生变化。螺旋藻不被螺旋藻用于粘附在表面上。取而代之的是，观察到结构和成分复杂的分泌胶，将动物牢固地附着在水下。这项研究的结果为进一步研究刺ni的粘附性和建立大肠杆菌奠定了基础。