GEOapplication/xmlftp://ftp.ncbi.nlm.nih.gov/geo/series/GSE338nnn/GSE338599/primaryOK200TranscriptomicsHydra vulgarisExpression profiling by high throughput sequencinghttps://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE338599GEOGSEfalseStructural assembly of the glycan-rich, chitin-reinforced adhesive of Hydra is coordinated by a lectin-like protein, HvAb1Aquatic animals deploy adhesives, in numerous essential functions, and reversibility is a key adaptation. The molecular mechanisms of reversible wet adhesion remain poorly understood. Using a model organism, the freshwater cnidarian Hydra vulgaris, we dissect the mechanism of molecular assembly in a secreted adhesive and uncover a glycan and protein-based architecture organized by a lectin-like protein, Hydra vulgaris adhesive protein 1 (HvAb1). We identify HvAb1 as a nonredundant organizer of the adhesive matrix, being basal-disc specific and secreted. Knockdown of HvAb1 severely impaired attachment and disrupted footprint architecture in a mosaic pattern, with only HvAb1-positive regions of the adhesive footprint retaining their normal structure. The adhesive is wheat germ agglutinin (WGA)-reactive and contains a fibrillar chitin-based sub-network, synthesized by a basal-disc-specific chitin synthase. Applying exogeneous chitinase abolished both WGA staining and Hydra attachment, indicating that WGA-positive components perform essential roles in adhesion. Our results therefore describe a glycan-dominated matrix, organized via a lectin-like protein (HvAb1), which is reinforced by chitin and enables reversible adhesion underwater. This establishes Hydra as a tractable model to better understand the principles of reversible adhesion underwater and, potentially, inform future bioinspired, sustainable adhesives.2026/07/21GSE338599GSM9877987GSM9877988GSM9877989GSM9877984GSM9877985GSM9877986GSM9877990GSM9877991GSM987799237207338599Hydra vulgaris