Glyphosate is a broad-spectrum herbicide widely employed in agriculture. Exposure to this genotoxic and endocrine-disrupting compound has adverse effects on terrestrial and aquatic organisms and on humans as well. Here, we explored the effects of glyphosate on female reproductive output and somatic growth rate in the marine polychaete worm,Ophryotrocha diadema.Adult focal individuals were exposed to different concentrations of pure glyphosate (0.0, 0.125 0.250, 0.500, 1.000 µg/mL) administered once a week for 3 weeks. Toxic effects and mortalities were observed at the three higher concentrations, whereas only a decrease in growth rate was noted after exposure to 0.125 µg/mL, which did not affect female allocation. An area of focus in future studies should be the effects of contaminants, their metabolites, and ecologically relevant human-driven stressors in the context of global warming.