When studying Antarctic fishes and invertebrates, a trend towards a higher maximum life span (MLSP) is found in polar ectotherms compared to their temperate relatives. Antarctic waters are characterized by year around constant low temperatures between +1.5 and -2.5 °C, whereas species from temperate coastal waters can experience comparably wide temperature fluctuations (0-18°C). Temperature has an impact on metabolic rates and, presumably, on the intensity of metabolical reactive oxygen species (ROS) formation in marine ectotherm species. We investigated chronological and physiological ageing in Antarctic and temperate bivalves: two burrowing mud clams, the Antarctic Laternula elliptica (Antarctic Peninsula, MLSP >36years) and the temperate Mya arenaria (North Sea, MLSP ~ 13years), and two swimming scallops, the Antarctic Adamussium colbecki (Terra Nova Bay, MLSP >35years) and the temperate Aequipecten opercularis (Irish Sea, MLSP ~ 8 years). Physiological age parameters were grouped into: ROS generation, antioxidant defence systems, and ROS damage parameters. Antioxidative defence decreased and oxidative damage accumulated with age in L. elliptica, A. colbecki and A. opercularis, whereas in M. arenaria antioxidant capacities increased and no significant change in oxidative damage occurred over lifetime. Tissue redox state (GSSG:GSH) became more oxidized in M. arenaria and more reduced in the other three species. In line with this, only isolated mitochondria from M. arenaria displayed high H2O2 generation rates and an elevated proportion of conversion of oxygen to ROS during respiration in older animals. H2O2 production by mitochondria from the polar clams was low (L. elliptica) or absent (A. opercularis, A. colbecki). Possible causes for the differentiation of aging in the 4 clam species can be in part explained by their different activity scopes and climatic background.