Individual performances in sun orientation ofTalitrus saltator(Montagu) were analysed in order to test phenotypic variability within the progeny of pairs of sandhoppers from a natural population. Most individuals in each family tested were individually oriented, although not all in the expected direction towards the sea. Thus the «scattered» behaviour shown by some of the families arises from different individual decisions and not from general «lack of decision». In a comparison between the orientation of expert adults and inexpert young, the latter tended to show higher deviation values. The importance of genetic heterogeneity and its interplay with phenotypic plasticity in the adaptation of sandhoppers is discussed.