Purpose in Pattern: The Evolution of Colour in Chromodorid Nudibranchs

Abstract

The function of colour patterns in chromodorid nudibranchs is discussed. The occurrence of sympatric groups of similarly coloured, but unrelated, species and the elaboration of mantle glands containing antifeedant chemicals suggests that these groups may comprise an example of aposematic Müllerian mimicry. The chromodorid fauna of southeastern and southern Australia is examined in detail. It is suggested that although chromodorid colour patterns most probably always have a defensive role, this is not always aposematic. As well as colour camouflage it is suggested that relatively rare species with bright, obvious and unique colour patterns are ignored by predators because of their novelty.