Vanishing Wars: The Affect of Camouflage in Nature
Biology 342 Fall 2014
How Does Camouflage Work?
Camouflage works by doing two very important jobs. The first is that the camouflage has to break up the outline on an object to make it less likely to be noticed by an observer. But once an object has been noticed it will then need camouflage that makes it difficult to recognize as what it truly is. Combining these two competing traits is the hallmark of any good camouflage but it is best to try and explain these features using some visual aids.
In this figure researchers are displaying the results of their experiment into various camouflage patterns meant to confuse birds into not finding a dead meal worm pinned onto a piece of paper against an oak tree. The research team used a waterproof paper triangle with a type of camouflage pattern printed as a means of hiding the meal worm. It was determined that using three different types of patterns in two different color sets would be an appropriate way to test the effectiveness of each pattern. The six different patterns are composed of patterns where the patches do not go past the edges, where they do, and where no patches are used at all. These patches were meant to simulate the types of shadow that exist between the ridges of oak tree bark. In the key provided the different acronyms correspond with whether or not the patches were allowed to go past the edges, E for yes and I for no, whether or not the background luminence matched that of oak tree bark, M for yes and NM for no, and finally the A marks any patterns that did not use patches. (The different patterns used in this experiment are shown below to give a better idea of what the discriptors visually represent). Based on this the researchers measured whether the meal worm had been eaten over the course of two days. Those curves that read higher on the scale indicate patterns that were better able to hide the meal worm. The two most successful patterns were where the patches went past the edges of the paper with matching luminence and where the patches did not go past the edges of the paper with matching luminence; however, the pattern where the patches continued on past the edges was more effective than where the patches could not continue past the edges. The solid color of matching luminence to the oak bark and where the edges went past the paper and the luminence was the same were not terribly effective and the other patterns that did not match the luminence for the tree bark were the worst performing of all. What this figure does is help to prove the veracity of my claim above that for camouflage to be effective it first needs to break up the outline of the object and it must not look like an object of interest to an animal. If you would like to learn more go to, this link.
In order for camouflage to be effective it has to break up the outline of an animal into a shape that is difficult for the brain to register as something that isn't a feature of the environment. This in turn leads to camouflage trying to primarily produce what is essentially noise that confuses a viewer into thinking that it is seeing something that is different than what the object actually is. In the photo on the left, seagull eggs are left out in the open with no one to guard them. The only thing standing between these eggs and someone's breakfast is their unique spots. In the image the patterns of spots are meant to break up the edges of the egg and make it seem more like the ground. This is done through the usage of high contrast colors to create regions that give a visual cue of depth and textures that cannot possibly be present on the eggs. By breaking up the standard shape of the egg the eggs are harder to spot and harder to recognize as eggs when your eyes are searching for the objects. What assists in this is the usage of colors that do not stand out as easily within this environment. The dark brown spots against the light khaki field do not help to draw attention to the eggs.
In the photo on the right is a coral reef that has one wily individual, an octopus sitting somewhere along the ocean floor. What makes this camouflaged animal so hard to locate isn't that it's particularly difficult to see, at least on the full size image. What makes the octopus hard to find is the fact that it is sitting in plain sight but it appears to be an object that no one would ever suspect as being an octopus. This animal hasn't hidden by being unable to be seen, it's hiding by being unable to be told apart from the random objects in the ecosystem. Not many people realize that camouflages can be effective when an object is spotted, so long as that object is not recognized. If the object can be observed but seen as a part of the landscape or as an object of no interest to the observer, then the camouflage has been just as effective as a pattern that made it hard to simply see the animal in the first place. If you're still struggling to locate this illusionist of an octopus, try looking in between the two clumps of pink coral. There's a certain red and white colored shape that just doesn't seem to be made from a calcium carbonate skeleton.
In order for these potoo birds, shown on the left, to have effective camouflage they must be able to break up the outline of the animal and make it appear more like a tree. The head of the potoo is somewhat easy to make out on its own but towards the tail end of the bird it is much harder to distinguish between the animal and the tree it is resting on. If you stare closely at the tail of the bird it becomes harder to recognize the beak and closed eye towards the tip of the branch. What is happening here is that while realizing that there is an object here is not a difficult exercise, it is hard to recognize what exactly the object is with just a casual glance. The only way to determine that what you are seeing is a bird is to pay close attention to the image and move your visual focus around the entire image. This increases the amount of time needed in order to complete the overall process which gives the potoo some extra time. What is happening here is a classic usage of camouflage to overcome an issue of being seen by appearing to something that does not need to be seen, unless you're looking for a spot to perch on. By making themselves hard to identify, potoos can avoid less intelligent animals and animals that have do not have very clear vision.