The sea walnut Mnemiopsis leidyi: from ecological nuisance to potential biological resource

This review synthesizes current knowledge on the sea walnut Mnemiopsis leidyi, focusing on its potential as an emerging source of bioactive compounds rather than solely as a marine invader. The Ponto–Mediterranean expansion of the species and its ecological impacts are briefly outlined to provide context on the origin and magnitude of available biomass. Particular emphasis is placed on biological traits, physiological plasticity, and environmental tolerance that enable recurrent production of large gelatinous stocks. Recent evidence indicates substantial biochemical diversity, including antibiofilm and antimicrobial peptides, photoproteins, and a largely unexplored immuneassociated molecular space with potential biotechnological and pharmaceutical relevance. These characteristics position M. leidyi as a promising candidate for biorefinery approaches aimed at extracting high-value molecules from low-cost marine biomass. However, pronounced spatial and temporal variability, together with the inherent unpredictability of natural blooms, represents a major bottleneck for reliable biomass supply and industrial exploitation. Addressing this constraint will require complementary strategies to stabilize production and improve process scalability. By integrating ecological context with biochemical and applied perspectives, this review identifies key challenges, knowledge gaps, and future directions for the sustainable valorization of gelatinous marine biomass and its derived biomolecular resources