Leaf insects (Phasmatodea: Phylliidae) exhibit perfect crypsis imitating leaves. Although the special appearance of the eggs of the species Phyllium philippinicum, which imitate plant seeds, has received attention in different taxonomic studies, the attachment capability of the eggs remains rather anecdotical. We herein elucidate the specialized attachment mechanism of the eggs of this species and provide the first experimental approach to systematically characterize the functional properties of their adhesion by using different microscopy techniques and attachment force measurements on substrates with differing degrees of roughness and surface chemistry, as well as repetitive attachment/detachment cycles while under the influence of water contact. We found that a combination of folded exochorionic structures (pinnae) and a film of adhesive secretion contribute to attachment, which both respond to water. Adhesion is initiated by the glue, which becomes fluid through hydration, enabling adaption to the surface profile. Hierarchically structured pinnae support the spreading of the glue and reinforcement of the film. This combination aids the egg’s surface in adapting to the surface roughness, yet the attachment strength is additionally influenced by the egg’s surface chemistry, favoring hydrophilic substrates. Repetitive detachment and water-mediated adhesion can optimize the location of the egg to ensure suitable environmental conditions for embryonic development. Furthermore, this repeatable and water-controlled adhesion mechanism can stimulate further research for biomimeticists, ecologists and conservationalists.

中文翻译：

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菲律宾叶昆虫毛yl（Phyllium Philippinicum（Phasmatodea：Phylliidae））在卵中的粘附性能。

叶片昆虫（昆虫纲：Phylliidae）表现出完美的模仿叶片的低温昆虫。虽然Phyllium philippinicum种的卵有特殊的外观模仿植物种子的种子，在不同的分类学研究中受到关注，卵子的附着能力仍然很奇特。我们在这里阐明了该物种卵的特殊附着机制，并提供了第一个实验方法，通过使用不同的显微镜技术和对具有不同粗糙度和表面化学程度的基质的附着力测量，系统地表征了它们的粘附功能特性作为在水接触的影响下的重复附着/分离循环。我们发现折叠的exochorionic结构（羽绒）和粘合剂分泌膜的组合有助于附着，这两个都响应水。粘合是由胶水开始的，胶水通过水合作用变成液体，能够适应表面轮廓。层次结构的耳廓支撑胶水的铺展和薄膜的加固。这种组合有助于鸡蛋的表面适应表面粗糙度，但是附着强度还受鸡蛋表面化学性质的影响，因此有利于亲水性基质。重复脱离和水介导的粘附可以优化卵的位置，以确保适合胚胎发育的环境条件。此外，这种可重复且受水控制的粘附机制可以激发仿生学家，生态学家和保护主义者的进一步研究。然而，附着强度还受蛋的表面化学性质的影响，有利于亲水性基质。重复脱离和水介导的粘附可以优化卵的位置，以确保适合胚胎发育的环境条件。此外，这种可重复且受水控制的粘附机制可以激发仿生学家，生态学家和保护主义者的进一步研究。然而，附着强度还受蛋的表面化学性质的影响，有利于亲水性基质。重复脱离和水介导的粘附可以优化卵的位置，以确保适合胚胎发育的环境条件。此外，这种可重复且受水控制的粘附机制可以激发仿生学家，生态学家和保护主义者的进一步研究。