Suspended animation, a state of profound metabolic, behavioral and developmental quiescence, is a remarkable yet poorly understood stress resilience strategy in animals. Here, we describe a previously uncharacterized form of suspended animation inducible by high-population density in isosmotic liquids in C. elegans throughout larval development and adulthood. Transcriptomic, metabolomic, and live-cell activity reporter imaging analyses reveal striking molecular and cellular landscape changes caused by such liquid-induced suspended animation (LISA), including remodeling of gene expression programs, energy metabolites, lysosomal and mitochondrial morphology. Genetic screens identify mutants with altered stress responses and survival against LISA. While key endo-lysosomal regulators promote survival during LISA, organelle remodeling and a neuronal axis via downstream neuropeptide and cAMP/PKA signaling orchestrate behavioral awakening from LISA. Our findings define a facile paradigm for reversible SA, providing a powerful model system to uncover key molecular and cellular mechanisms governing an extreme case of reversible life arrest and dormancy.
