Cuttlefish (Sepia officinalis) juveniles were exposed to dietary MeHg and elevated pCO2 during their first living month. Behavioral analyses revealed an increase of the locomotor activity, an alteration of defensive behavior as well as a disruption of behavioral lateralization. Thus, we decided to study the transcriptome from the head of those individuals using RNA-sequencing technologie in order to investigate molecular mechanisms potentially underlying the neurotoxicity of MeHg and pCO2.