This study focused on verifying the fluctuating asymmetry hypothesisin the crustacean Talitrus saltator, which lives in sandy beaches.We analysed three populations, one from an unpolluted Tuscanbeach relatively free of tourism, and two from Sicilian beaches,which have been increasingly used for tourism and have been exposedto hydrocarbon/pesticide pollution. Results confirmed the sexualdimorphism in the second antennae flagella, which in the Tuscanpopulation presented directional asymmetry. This population hada significant level of fluctuating asymmetry in the P6 and P3 meri.The results showed the importance of the developmental stageduring which environmental mechanical stresses act.