Ocean acidification (OA), in conjunction with ocean warming, poses a grave threat to marine ecosystems and biodiversity worldwide. How these environmental challenges affect marine invertebrates remains largely unknown. Sea slugs have been proven to advance our understanding of how nervous systems function, serving as an essential model organism in neuroscience. While exploring every possible ecological niche, they evolved various defense and nutritional behavioral strategies, dealing with toxins such as TTX, to the ability to sequester stinging cells from cnidarian (kleptocnidy) or symbiotic intracellular storage of stolen chloroplasts from algae (kleptoplasty). These intricate, complex organism adaptations suggest unique types of learning and memory essential for the survival. Using two endemic “”organelle-stealing”” sea slugs, Elysia chlorotica and Cratena pilata, I aim to establish a toolkit to scrutinize the impact of environmental challenges on the behavior and physiology of sea slugs, capitalizing on the memory paradigm measurements and confocal microscopy to characterize changes in the neurons of the cerebral ganglion. Together, this project will provide an urgently needed toolkit for studying the environmental impact on the nervous system of sea slugs.