The ocean quahog Arctica islandica is equally attractive to physiologists and environmental scientists due to its long life span of up to 400 years . For physiology, A. islandica is an exciting age model whereas environmental sciences infer past environmental conditions from morphometric and biogeochemical properties of the calcareous shell. In order to evaluate whether and animals from different localities differ, the present study compared genetics and morphometry of six A. islandica populations, from the Norwegian Coast, Kattegat, Kiel bay, White Sea, German Bight and Off Ne Iceland. For genetics, present research found 30 haplotypes of the mitochondrial cytochrome B (cyt B) gene, of which some are widely distributed, whereas others are quite rare. There is no consistent geographical pattern in haplotype distribution, even when a further previously published 11 haplotypes are taken into account. For morphometry, discriminant analysis indicated significant morphometric differences, e.g. in shell shape, between populations which are independent of geographical distance. Moreover, genetic and morphometric patterns appear to be unrelated. Thus, present study reveals morphological differences between populations of A. islandica appear to be driven by the environment rather than underlying genetic differences between populations.