Ocean acidification is regarded as one of the most recent threats to the global environment resulting from unprecedented absorption of elevated anthropogenic carbon dioxide emissions. The emerging research on the effect of acidifying oceans on marine organisms collectively indicates a potential detrimental effect on biodiversity, particularly for aragonite-derived organisms. This in turn affects marine food webs that can impact on the livelihood of humans. An urgent need for multidisciplinary research is highlighted which, ideally, needs to be internationally coordinated. This will enable a better understanding of the predictability and effects of ocean acidification on marine biodiversity and can be implemented in mitigation and policy-making.