Copper (Cu) is a key trace element for many biological processes, but there is little available information regaring its requirements an functions in critical life stages of marine bivalves, uring which ramatic morphological an physiological changes occur. In this stuy, the ontogeny pattern of Cu accumulation across the life history of oysters was explore for the first time an the istributions of Cu in oysters at critical life stages (peiveliger an early settle spat) were in situ mappe by nanoscale seconary ion mass spectrometry (NanoSIMS) with high lateral resolution. We first emonstrate that the late pelagic stage to early settle stage was the critical stage requiring Cu uring oyster evelopment. NanoSIMS imaging reveale a significant elevation of intercellular Cu levels along with mitochonrial calcium overloa an obvious structural egraation of mitochonria in velar cells at the peiveliger stage, implying the possible role of Cu in cell apoptosis of the velum uring larval metamorphosis. Furthermore, an obvious enrichment of Cu together with calcium was observe in the nucleus an mitochonria of ciliate cells of gill tissue at the early settle stage. Their accumulation in the gill cells was significantly higher than that in the juveniles, inicating the potential role of Cu in sustaining the fast growth of the gill filament an the concomitant acceleration of energy metabolism uring early benthic evelopment. Our finings offer new insights into the unerstaning of the interactions between trace metals an marine bivalves.