Wildlife Photograph

Camouflage: The Natural Alternative to Being Eaten

Monday October 16, 2006
Animals have many methods of adaptation and survival. Read about one that humans have borrowed!

    When we think of camouflage we either think of animals in nature or military uniforms. In1915, the French army became the first to begin using modern camouflage. They created a camouflage division and employed artists to develop uniforms during WWI. The word camouflage comes from the French word camoufler, which means “to veil or disguise.” The military got the idea from watching animals in the natural world. Most animals use some form of camouflage to disguise themselves. This protective concealment allows animals to avoid detection by predators and to be better predators, in some cases.                                                                                                                                                           There are two basic methods of camouflage: general resemblance and special resemblance. Animals that use general resemblance use the color of their outer covering to blend in to their environment. They become almost invisible. Hares, grasshoppers, tree frogs and some lizards are examples of these. Animals that use special resemblance use a combination of color, shape, and behavior to appear to be something else. The best example is the walking stick, which looks and acts like a stick. Other animals that use special resemblance include; zebra, giraffe, leopards, snakes, caterpillars, butterflies and moths.                                                                         
    An animal that closely matches its surroundings is more likely to survive and have offspring. The animal’s offspring inherit its coloration and will also pass it on to its offspring. This process is called natural selection. A species will develop its camouflage slowly over time. If its environment changes, some species slowly change over time through natural selection. The successful members of a species will begin to match their new surroundings. If this does not occur, the population of the species may decline.                                 
    Some animals can change the color of their skin to match their immediate environment. One of the most common examples is the chameleon. In East Tennessee, the gray treefrog is able to do this. Gray treefrogs can change their color from gray to brown pr pale green. The change does not happen immediately, but occurs quickly enough that the frogs remain safe from predators. The color change is created by special pigment cells called chromatophores. These cells are star shaped and contain grains of pigment. It is by shifting distribution of the grains within the cells that coloration changes occur. If the grains of pigment are packed tightly together within the center of the chromatophores, the frog will appear light colored. When the grains of pigment spread out within the chromatophores, the frog appears darker in color. Different chromatophores can contain different pigments. This allows the frog to appear gray, brown or green. Color change can be brought on by   surrounding, temperature and other environmental factors. It is controlled by a combination of the retina, nervous system and hormones in the blood. Some other animals that can change the color of their skin using chromatophores include chameleons and the cuttle fish.                                              
    Use the upcoming beautiful fall days to see camouflage at work. Come hike at Ijams and see how many animals you can find trying to be invisible.

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