What colours would you choose for your camouflage to hide in some natural setting? Green comes to mind, probably brown, maybe yellow and black. But it may not be the best strategy – sometimes dazzling iridescent colours in animals work as a very good camouflage as was revealed by a new study from the University of Bristol. Turns out, such bright colours can confuse bumblebees.
Camouflage is not just something that is impossible to see because it blends in to its background. It can be something that features weird colours and patterns that break the contour of the thing or are plain confusing. Iridescent colours, constructed from repeating nanostructures to reflect light at slightly different angles, are quite common in nature. Some beetles have iridescent elytras and peacocks feature similar colours in their tails. Humans find these colours rather beautiful – there are bright, metallic and unique in the nature background. But bumblebees get confused by the – this new research showed that iridescent colours obstruct bumblebee’s ability to identify the shape of the object.
Scientists found a nice way to figure this out. They placed some fake colourful flowers for bumblebees to enjoy. Some of them had sugar water and bumblebees quickly learned to recognize them by shape. But if the flower was iridescent bumblebees had much more trouble. This is not just about bumblebees – their eyes are similar to predatory insects such as wasps and hornets. This could explain why sometimes dazzling iridescent colours are so common between beetles – it may be a form of camouflage. Soldiers use camouflage for the same reason – it breaks their contour and make them more difficult to notice for the enemy.
Up until now it was assumed that iridescent colours have two main advantages – they help finding mates and they can act as a warning that the beetle may be poisonous. However, over one hundred years ago American naturalist named Abbott Thaye argued that iridescence could be a form of camouflage. It is said that his work might have inspired the “Razzle Dazzle” painting of battleships during the First World War. But after that the link between iridescence and camouflage was sort of forgotten until now. Dr Karin Kjernsmo, lead author of this new study, said: “This study has wider implications for how we understand animal vision and camouflage – now when we see these shiny beetles we can know that their amazing colours have many more functions than previously thought”.
Evolution has always been described as survival of the fittest. Iridescent colours allowed for the survival of these beetles because predators couldn’t recognize them. Now scientists want to see if the effect can be found between birds as well – they are the primary predators for these dazzling beetles.
Source: University of Bristol