Animals are generally interested in three things: food, sex and staying alive. For the last part, there are many different camouflage strategies which animals use to hide from their predators. We spoke to Dr. Martin Stevens, leader of the Sensory Ecology Group at the University of Exeter to find out more.
When most people think of camouflage they focus on one particular type called background matching in which animals evolve to blend in with their surroundings. This could be relatively simple strategies such as matching body colour to your surroundings or the more complex camouflage of insects which have evolved to look and behave like sticks or leaves.
Counter shading is another straightforward camouflage technique which is common in many marine species. Many fish have darker colours on top and lighter colours below to act as camouflage in their 3D world. Look down from above and the dark colour blends in with the abyss of the ocean beneath, look up from below and the light bellies are camouflaged against the sunlight. This is a good strategy for fish to try to hide from their predators but it can also work the other way around. Sharks use counter shading to help them hunt: prey species that are below the shark may not see the beast coming until it is too late.
Disruptive colouration is a different camouflage strategy in which animals disguise their identity. This type of camouflage seeks to confuse, not conceal and it’s one of the theories proposed for why zebras evolved stripes. The idea is that the black and white markings dazzle the zebras’ predators so that it is difficult to pick out individual animals amidst a herd of moving stripes. The Sensory Ecology group have tested this idea in humans using video games in which participants had to capture moving prey targets on a screen. They found that striped targets are more difficult to capture, possibly due to a similar motion dazzle effect experienced by lions hunting zebra.
Disruptive camouflage was also applied to military ships, particularly during World War 1. First suggested by zoologist John Graham Kerr, the “razzle dazzle” strategy saw ships painted with irregular stripes to try to tap into some of nature’s camouflage secrets. Although they looked very conspicuous on their own, as a moving target the ships’ stripes made it more difficult to identify their size, speed and direction of movement.
It’s important to remember that camouflage is in the eye of beholder. Different species have different visual capabilities so something that appears hidden to the human eye could be very conspicuous to other predators. In their Project Nightjarstudy, Dr. Stevens and his team are studying how camouflage works in the wild. They photograph the eggs, chicks and adults of ground nesting birds (nightjars, plovers and coursers) and use visual models to test how camouflage patterns in these species appear to other individuals and their predators. Their citizen science games are fun ways to contribute to this fascinating research.
*Sive Finlay: Zoologist and researcher for Futureproof, @SiveFinlay
