The study investigated the proteomic response of the colonial tunicate Botryllus schlosseri to acute copper exposure and subsequent recovery. DIA analysis was performed on Botryllus schlosseri colonies exposed to copper concentrations of 0 µg/L (control, C0), 300 µg/L (C3), and 900 µg/L (C4) for 24 hours (Exposure phase, E). To assess recovery (R), a subset of colonies from each condition was transferred to clean seawater for an additional 24 hours. Each condition included 11 biological replicates, collected by pooling ≥15 zooids per sample (including vascular network and ampullae).