I know the zooxanthellae has the color. But why do corals exist in different colors? Some corals like favias, brains and zoas have very well defined multiple colors. Some say flowers are brightly colored to attract bees so they will be pollinated. Some animals such as birds are brightly colored to attract mates. What is the biological advantage to corals being brightly colored? Since they are immobile they can't attract mates. As far as I know they don't receive assistance by any other animal in breeding. You would think that being brightly colored would be a disadvantage since they would be easier to spot by butterfly fish and angles (unless they don't see in color). If zooxanthellae take on different colors based on the amount of light they receive why are some corals multicolored? So what's the reason? It can't be just for our pleasure.