One of the things that this adaptation or strategy for adaptation requires is that the potential predator has to experiment on this organism.
The predator has to try to eat it and to learn from that experience, to associate that color pattern with an unpleasant experience in tasting something that's toxic or distasteful and hopefully survive that encounter, to remember it and to the associate that color pattern with that unpleasant experience. That is the philosophical basis on which these aposematic or warning coloration really exists.
Well, when we go to the marine environment, our understanding of color patterns is really not as well developed as it has been in the terrestrial environment. Basically for about 150 years people have been studying patterns of mimicry, the adaptive significance of having aposematic coloration or communication coloration but in the marine environment the roles of coloration have not been nearly as well studied. Basically this is because of limited access until relatively recently. With the advent of things like scuba diving and other things that enable one to actually have a prolonged period of observation in these kinds of marine habitat our understanding has grown.
But one of the things that we certainly notice about the marine environment is that there are brightly colored fish species and particularly on coral reefs there are very distinctive patterns. In areas where there is high diversity, where there may be upwards of 400 or 500 different species of coral reef fish inhabiting a single small reef the size of this room, one of the important things for those organisms to realize and recognize is the differences between individuals. Organisms have to be able to recognize members of their own species and distinguish them from all other species.
In the case of coral reef fishes, particularly in coral reefs where a lot of the fish species actually changed sex over their life history, they know by sending signals and messages, who are members of the same species, what their reproductive mode is, and in what phase of reproduction they are. They send these messages to members of their own species. It is absolutely essential to setting up hierarchies of territoriality and also obviously for courtship and mating. So, this is basically the equivalent of the blue footed booby that I showed you, that the color patterns that you see are largely designed to send messages to members of their own species about their reproductive and social status within that species.