Collection, handling and care of cephalopod eggs

Research on cephalopod early ontogeny has significantly advanced in recent decades, including embryo organogenesis and neurogenesis and early behavioural adaptations, particularly in commercially important and coastal species. Within this context, here we compiled current knowledge on the collection, handling and care under experimental conditions and monitoring in the field of cephalopod eggs and egg masses. It covers field observations and egg collection methods, as well as laboratory incubation protocols for eggs maintained with and without maternal care. It is emphasized how abiotic and biotic factors, including temperature, salinity, oxygen and maternal condition, shape embryonic development and hatchling survival and viability. Monitoring methods for cephalopod egg masses in the wild and the effects of natural threats such as storms and predators are reviewed. Anthropogenic impacts such as pollution, fisheries and climate change are also discussed. Technological advances have enabled finer analysis of neural development as the embryo grows, while ethical considerations regarding embryonic sentience capacity and welfare conditions are becoming central to current experimental designs. Based on current knowledge, it is recommended to apply ethical considerations and the 3Rs principle (Replacement, Reduction, Refinement) for cephalopod embryos following the onset of organogenesis. Thus, a list of potential indicators of health and welfare that could be used for assessing and monitoring cephalopod embryos and hatchlings is proposed. Overall, this synthesis aims to serve as a guide for advancing egg collection and laboratory incubation methodologies, as well as adopting ethical handling protocols to improve cephalopod embryo care and quality.