Project Summary/Abstract: Within aquatic biomedical models, thousands of valuable research lines are created and characterized each year by numerous methods including mutagenesis, gene transfer, gene editing, gene knockout, hybridization, and backcrossing. Among the five NIH‐funded aquatic stock centers, preservation of haploid germplasm (sperm) is possible for three groups: zebrafish, Xiphophorus and Xenopus. Currently there is no practical method available for preservation of diploid germplasm (e.g., embryos or larvae) for any aquatic group. This problem is especially prominent for the sea hare, Aplysia californica, which because of reproductive traits (non‐self‐fertilizing hermaphroditism) requires cryopreservation of early life stages rather than sperm. The availability of cryopreserved diploid germplasm would greatly accelerate the availability of numerous research lines by removing needs for screening and production of multiple generations to produce homozygosity. Thus, the community needs for preservation and use of genetic resources would be greatly advanced for all aquatic biomedical models by novel technologies for cryopreservation of embryos and larvae, and this technology is essential for Aplysia. Therefore, our goal is to develop novel electro‐cryobiology technologies to monitor and improve vitrification and cryo‐recovery protocols for diploid genomes of aquatic biomedical models. The Specific Aims are to: 1) develop novel technologies for ultra‐rapid monitoring (millisecond) of cryogenic processes associated with Aplysia embryo vitrification; 2) use the novel monitoring technology to gain new insights into traditional approaches for Aplysia embryo vitrification, and 3) expand the monitoring technology to allow interaction with cryogenic processes to gain new approaches for Aplysia embryo vitrification. This work, although focused on Aplysia for the supplement, would be useful for embryos and sperm of frogs, salamanders, and fishes, and would provide preliminary data needed for future grant proposals to expand utility and application. This supplement would be extremely valuable in advancing the parent award by adding powerful new approaches (Aim 1) that would greatly accelerate our current conventional research (Aim 2), and it would provide us with novel tools to establish new approaches (Aim 3). The parent award (and other R24 funding) has allowed us to assemble a unique interdisciplinary group with more than 15 years of expertise in all aspects of this work spanning reproductive biology, cryobiology, engineering, and device fabrication. This work can be completed within the current project year (entering Year 3), and it does not overlap with work funded in the parent award or through previous supplemental funding.