Organisms living in the marine environment contain a number of primary and secondary metabolites which are involved in bioadhesive processes. Much progress has been made regarding the characterization of underwater adhesive structures utilized by sessile invertebrates such as barnacles, mussels, and tubeworms. The structural components and biochemical mechanisms involved in the wound-plug forming process in marine siphonous green algae have received far less attention. This review focuses on the lectin-carbohydrate and protein cross-linking strategies that serve as the basis for wound plug formation in siphonous green algae. Based on structural considerations it should be noted that cross-linking mechanisms are ubiquitous features of a variety of marine taxa that have been previously overlooked.