Animals are evolving to ever-changing environments. Currently, there are global concerns over environmental changes related to CO₂ emissions from anthropogenic activities. Marine environments are particularly under threats of increasing temperatures and ocean acidification. All of ongoing and anticipated impacts on marine ecosystems are related to natural selection and the adaptation of marine organisms to environmental change. If organisms cannot adapt to the changing environments, they will disappear. In contrast, some organisms may adapt to novel conditions and in fact some appear to benefit. Different adaptive landscapes among species will lead to shift in the community composition and eventually change ecosystems. To understand and predict the effects of climate change and ocean acidification on marine ecosystems, knowledge about the adaptation of marine organisms to the environmental changes is required.

Given the trend of CO₂ increase and ocean acidification will be hard to reverse, we must understand how species and populations will survive and reproduce under future environmental conditions. Many studies have suggested that ocean acidification has generally negative influences on marine organisms and ecosystems (Orr et al. 2005; Barry and Drazen 2007; Dashfield et al. 2008; Kuffner et al. 2008), but others have highlighted the differential response among species and life stages to decreased pH (Dupont et al. 2008; Ries et al. 2009; Kroeker et al. 2010). We still have a poor understanding of how species vary in their ability to cope with acidified seawater. Moreover, the roles of genetic variation and phenotypic plasticity in influencing responses of marine organisms to ocean acidification are just beginning to be explored. I  explore the ability of marine invertebrates to adapt to ocean acidification using a variety of techniques used in multiple disciplines such as demography, morphometrics, behavior and physiology.