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Abstract BackgroundThe biofouling marine tube worm,Hydroides elegans, is an indirect developing polychaete with significance as a model organism for questions in developmental biology and the evolution of host‐microbe interactions. However, a complete description of the life cycle from fertilization through sexual maturity remains scattered in the literature, and lacks standardization. Results and discussionHere, we present a unified staging scheme synthesizing the major morphological changes that occur during the entire life cycle of the animal. These data represent a complete record of the life cycle, and serve as a foundation for connecting molecular changes with morphology. ConclusionsThe present synthesis and associated staging scheme are especially timely as this system gains traction within research communities. Characterizing theHydroideslife cycle is essential for investigating the molecular mechanisms that drive major developmental transitions, like metamorphosis, in response to bacteria. 

Abstract BackgroundSea urchin embryos have been used for more than a century in the study of fertilization and early development. However, several of the species used, such asStrongylocentrotus purpuratus, have long generation times making them suboptimal for transgenerational studies. ResultsHere, we present an overview of the development of a rapidly developing echinoderm species,Lytechinus pictus, from fertilization through sexual maturation. When grown at room temperature (20°C) embryos complete the first cell cycle in 90 minutes, followed by subsequent cleavages every 45 minutes, leading to hatching at 9 hours postfertilization (hpf). The swimming embryos gastrulate from 12 to 36 hpf and produce the cells which subsequently give rise to the larval skeleton and immunocytes. Larvae begin to feed at 2 days and metamorphose by 3 weeks. Juveniles reach sexual maturity at 4 to 6 months of age, depending on individual growth rate. ConclusionsThis staging scheme lays a foundation for future studies inL. pictus, which share many of the attractive features of other urchins but have the key advantage of rapid development to sexual maturation. This is significant for multigenerational and genetic studies newly enabled by CRISPR‐CAS mediated gene editing.