Helmut Corneli/Alamy Some corals can swap out the algae that live inside their tissues for different strains that are more heat tolerant – and these coral species have a better chance of surviving global climate change in the coming decades. When sea temperatures are too high, corals expel the microscopic algae living in their tissues. This is what occurs during coral bleaching. Losing algae in this way is harmful for the corals because the algae normally provide oxygen for them and remove their waste products. However, marine biologists have previously discovered that when some corals are exposed to warmer temperatures, they can swap the algae inside their tissues for strains that have a higher thermal tolerance.