Pearl oysters, Pinctada margaritifera, were exposed to 15 pH conditions ranging from 8.0 to 6.6, for 16 days, in order to determine their reaction norms to ocean acidification at all physiological scales, from the gene to the organism. The following physiological parameters were monitored: survival, byssus, ingestion, calcification, shell, periostracum, carbohydrate reserves, carbonic anhydrase activity, fatty acid composition of cell membranes, and gene expression (transcriptomics). Then, for detecting potential adaptation to ocean acidification, the gene expressions of the tropical subtidal oyster, P. margaritifera, were compared with the gene expressions of the temperate intertidal oyster Crassostrea gigas, re-using data from our previous study (Lutier et al., 2022, https://doi.org/10.1111/gcb.16101).