BACKGROUND Octopus vulgaris has been an iconic cephalopod species for neurobiology research as well as for cephalopod aquaculture. It is one of the most intelligent and well-studied invertebrates, possessing both long- and short-term memory and the striking ability to perform complex cognitive tasks. Nevertheless, how the common octopus developed these uncommon features remains enigmatic. O. vulgaris females spawn thousands of small eggs and remain with their clutch during their entire development, cleaning, venting and protecting the eggs. In fact, eggs incubated without females usually do not develop normally, mainly due to biological contamination (fungi, bacteria, etc.). This high level of parental care might have hampered laboratory research on the embryonic development of this intriguing cephalopod. RESULTS Here, we present a completely parameter-controlled artificial seawater standalone egg incubation system that replaces maternal care and allows successful embryonic development of a small-egged octopus species until hatching in a laboratory environment. We also provide a practical and detailed staging atlas based on bright-field and light sheet fluorescence microscopy imaging for precise monitoring of embryonic development. The atlas has a comparative section to benchmark stages to the different scales published by Naef (1928), Arnold (1965) and Boletzky (2016). Finally, we provide methods to monitor health and wellbeing of embryos during organogenesis. CONCLUSION Besides introducing the study of O. vulgaris embryonic development to a wider community, this work can be a high-quality reference for comparative evolutionary developmental biology.

中文翻译：

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实用的分期图集，用于在受控实验室条件下研究普通章鱼的胚胎发育。

背景普通章鱼一直是神经生物学研究以及头足类水产养殖的标志性头足类物种。它是最聪明、研究最透彻的无脊椎动物之一，拥有长期和短期记忆以及执行复杂认知任务的惊人能力。然而，普通章鱼如何形成这些不常见的特征仍然是个谜。O. vulgaris 雌性会产下数千个小卵，并在整个发育过程中一直留在自己的窝里，负责清洁、通风和保护卵。事实上，没有雌性孵化的卵通常不能正常发育，主要是由于生物污染（真菌、细菌等）。这种高水平的父母照顾可能阻碍了对这种有趣的头足类动物胚胎发育的实验室研究。结果在这里，我们提出了一种完全参数控制的人工海水独立卵孵化系统，该系统取代了母体护理，并允许小卵章鱼物种成功胚胎发育，直到在实验室环境中孵化。我们还提供基于明场和光片荧光显微镜成像的实用且详细的分期图集，用于精确监测胚胎发育。该地图集有一个比较部分，用于对 Naef (1928)、Arnold (1965) 和 Boletzky (2016) 出版的不同尺度的基准阶段进行比较。最后，我们提供了在器官发生过程中监测胚胎健康状况的方法。结论除了向更广泛的群体介绍普通O. vulgaris胚胎发育的研究之外，这项工作可以成为比较进化发育生物学的高质量参考。