Comment on Holothurian Phyllidia mimic by Wolfgang Seifarth. I gave the example that the flatworm Pseudoceros imitatus mimics Phyllidia pustulosa . My guess is that flatworms 'tried' a number of colours and patterns by chance, and that the Pseudoceros pattern was selected through increased survival because of its likeness to Phyllidia . Dear Christine, Mimicry is a good example of evolution at work. It is difficult not to give human attributes to animals when explaining how evolution works but it is important not to give the impression that the process is 'guided towards perfection'.
Evolution is directionless.
To say they 'tried' a number of patterns suggests they were aiming at a goal which is quite the wrong way to approach it. If, or rather when, environmental conditions change, there is a good likelihood that some members of a very variable species will be able survive in the new conditions and so pass on their selection of the original genes to the next generation. In the case of Phyllidia and the flatworm, let us presume that Phyllidia is the 'model'. Phyllidia has extremely toxic and distasteful secretions which deter fish from eating it. Fish learn to avoid the Phyllidia -shape and colour and so Phyllidia are somewhat protected from predation.