Long-lasting embryonic dormancy in invertebrates defies our understanding of what constitutes life because, for example, eggs of some copepods can delay hatching for decades or even centuries. Copepods, often millimeter-sized crustaceans, are some of the most numerous multicellular organisms on earth and are key organisms in most aquatic food webs. Some important free-living marine and estuarine species overwinter or oversummer by arrested embryogenesis in dormancy. The present contribution discusses the complex mechanisms behind embryonic dormancy by compiling knowledge from the 42 calanoid copepods from the superfamily Centropagoidea with well-described embryonic dormancy, which has been of scientific interest for decades. However, the determination of categories of copepod resting eggs—that is, diapause and quiescence, transitions between categories, the mechanisms controlling arrested development by the embryos, and how they interact with their surroundings—is not fully understood. Moreover, a clear link between the presence of the free-swimming population and their resting eggs in sediments is still not convincingly demonstrated. Here I evaluate the relative significance of potential cues driving the production of and the phase shift between egg categories. Understanding the initiation and termination of embryonic dormancy is of great importance for fundamental science—that is, population and food web ecology as well as climate science, aquaculture live feed, and ballast water research. Molecular techniques are developing rapidly, especially within health sciences, thus providing relevant tools applicable for plankton research. Here I suggest that applying molecular methods in addition to traditional physiological approaches in future research will lead to greater understanding of copepod embryonic dormancy, one of nature’s wonders.

中文翻译：

---

桡足类胚胎休眠：“鸡蛋不仅仅是鸡蛋”

无脊椎动物的长期胚胎休眠违背了我们对生命构成的理解，因为例如，一些桡足类动物的卵会延迟孵化数十年甚至数百年。桡足类，通常是毫米大小的甲壳类动物，是地球上数量最多的多细胞生物之一，也是大多数水生食物网中的关键生物。一些重要的自由生活海洋和河口物种通过在休眠中阻止胚胎发生而越冬或越夏。本论文通过汇编来自 Centropagoidea 总科的 42 种桡足类动物的知识来讨论胚胎休眠背后的复杂机制，这些桡足类动物具有良好描述的胚胎休眠状态，几十年来一直具有科学兴趣。然而，桡足类休眠卵类别的确定——即滞育和静止，类别之间的转换、控制胚胎发育停滞的机制以及它们如何与周围环境相互作用尚不完全清楚。此外，自由游泳种群的存在与其在沉积物中休息的卵之间的明确联系仍未得到令人信服的证明。在这里，我评估了驱动蛋类产生和相移的潜在线索的相对重要性。了解胚胎休眠的开始和终止对于基础科学（即人口和食物网生态学以及气候科学、水产养殖活饲料和压载水研究）非常重要。分子技术发展迅速，尤其是在健康科学领域，从而为浮游生物研究提供了相关工具。