Sönke Johnsen, Duke
Camouflage is exceptionally challenging in open ocean environments, due to their featureless nature. Thus, it is perhaps no surprise that the animal that live in this world have evolved highly sophisticated camouflage strategies, three of which – transparency, mirrors, and counterillumination – are rare or absent in all other habitats. The visual systems of the predators are equally complex, and several visual capabilities, including ultraviolet and polarization sensitivity and special filters filters, are thought to facilitate detection of camouflaged animals. This talk reviews the optical nature of this enormous and mysterious realm and both the camouflage and camouflage-breaking strategies of its inhabitants, focusing primarily on underlying principles and what remains to be discovered. A theme throughout is that far more is known about the optical and visual structures involved than about their function, and that this imbalance is primarily due to the rarity of observations of undisturbed behavior.