Camouflage and Mimicry: Final Paper

This topic submitted by Scott Popham ( pophamse@muohio.edu) at 10:45 PM on 6/5/08.

A green snake close-up, Hospital Pt, Panama.

Tropical Field Courses -Western Program-Miami University

The idea of camouflaging ones self has been around for a very long time, since long before the human race has ruled the earth. Animals are the originators of true camouflage and mimicry. Unlike humans that have to use foreign objects such as face paint and ghillie suits to camouflage themselves, animals have adapted their bodies for these changes. Some animals can just simply hide among its environment, while some animals have evolved to look like other more dangerous animals. No matter how camouflaged something is, without the right techniques they will easily be spotted. Throughout this paper I am going to be talking about the different types of camouflage, coloration, and techniques that allow animals to survive, thrive, and expand.
To begin talking about animal camouflage it is best to start with a definition. Dictionary.com identifies camouflage as Òconcealment by some means that alters or obscures the appearanceÓ. The word camouflage comes from a French word camonflet, which means a puff of smoke and moufler which means to cover up. In the animal kingdom camouflage describes not only a means of blending into a natural background but many devices by which a creature appears to be something its not. While doing research on this topic I realized that the topic of camouflage is a lot more in depth than any definition given. Originally I believed that camouflage was only the act of concealment in form of hiding. There are actually many different types of camouflage and each one has its advantages. It is important to start talking about vision when it comes to talking about camouflage. Vision is important because we must understand how the eye works in turn to know how to hide from it. When one can understand optical illusions and the laws of visions then they will be able to understand how camouflage is applied more easily.
Optical illusions are very disorienting and can lead to confusion. An optical illusion makes us feel that something has gone wrong with our senses and with our ability to judge things correctly. A psychologist by the name of Modern Gestalt did research and studies that were able to show that optical illusions are the work of the eye itself. What he proved was that the eye is the organizer rather than a passive receiver of impressions. What this means is that even though your eye sees one thing, another thing may actually be there. The eye will essentially make it things seem as less confusing as possible for the brain, and this is how optical illusions are presented.
The most important law of vision is the known as the law of good form. This law has a very large importance when it comes to camouflage. What this law means is that an animal has markings that run into the background then the eye will follow the continuity and confuse the animal with the surroundings. The more of these lines or spots and animal has the more difficult it will become to differentiate it between the environment.
Another law of vision is known as the joining effect. This is when an animal or multiple animals come to rest they create a disorienting pattern. For example if two frogs were alone their outline would be easily recognizable, but the second that these two frogs came together they would look more like a rock or a lump on the ground than a frog. Using the frog as another example, when they are moving their legs and outline can be distinguished very easily; however when the frog comes to rest and the legs are pressed up against its body then the markings on the legs blend with the body creating a dissembling effect.
The third law of vision is that of the maximum broken color effect. When concealing patterns appear with a strong contrasted tone the effect is more effective. This is because the severely contrasted tones draw attention away from the other details and especially those details of the animal. This law of vision combined with the adaptive nature of animals can create some astonishing effects. Adaptive behavior is extremely common in marine animals. What fish will do is resemble seaweed as it moves with the moving water. The fish will allow their body to move like the seaweed which makes them less recognizable than if they were to just remain motionless. Another example is how some freshwater fish will float down stream as if they were dead leaves. This adaptive behavior allows them to blend in extremely well with their surroundings by using the third law of vision.
As stated before there are many different types of camouflage, and I intend to describe each type. The first type is that of disruptive coloration. Disruptive coloration is closely related to the first law of vision, the law of good form. Take for example a diamondback rattlesnake. If it was to be seen on a plain background the black and yellow diamond pattern would stand out clearly. However if this same snake was in grasses, rocks, stick, and other debris the snake disappears from sight. This is an example of the outline of the animal being broken up by its markings and just blending into its surroundings. Disruptive coloration is any type of camouflage that uses spots, stripes, any type of pattern that blurs the animal from its background.
Another type of camouflage is concealment of shadows. For example the white coat of a rabbit in Alaska does little good for it if its shadow can be seen for miles against the white snow. What animals do to overcome this obstacle is described by the Òpeter pan effectÓ, not having a shadow. The closer an animal crouches to the ground the smaller its shadow, and the same effect can be created with flaps. Squids are an excellent example of an animal that crouches to reduce its shadow. Racing crabs use the peter pan effect a little different. When racing across the sand theses crabs will make for an indentation to hide their shadow when threatened. By dropping down into a depression their shadow is removed by the banks of the indentation. Shadows can also be lessened by something called active body orientation. For example an animal will turn its body with the constantly changing sun so that it shadow will remain as little as possible at all times.
Another method of doing away with shadow effects is counter-shading, which is also known as ThayersÕs principal. The way this works is; the parts of the animal on which the light shines, which is usually the back and the top of the head, are dark in color while the parts that are away from the light are light in color. Between the dark and light areas there is a gradual color gradient. This counter shading creates an effect that allows the animal to appear flat and to the eyes of a predator it may even be invisible against the background. Counter shading is a particularly effective camouflage tool in areas which break up shadows, for example, in long grass or woods. It is extremely effective for small defenseless animals. The larger and more powerful animals can deviate from this counter shading through evolution, but the smaller more defenseless animals just develop it better. Many types of fish have developed a more advance form of counter shading with use of different colors. On their top they have a blue color while underneath may be silver. This type of shading is due to the sky above and the sea below. The way that these animals produce this coloring effect is through their pigment. Pigment is contained in cells which lie in the surface layer of skin, fur, feathers, and exoskeleton of insects. These cells can be contracted or expanded which will create different shades of color for different situations.
Another type of camouflage is called masking. Much like how snipers create their ghillie suits by collecting material from surrounding areas to ÒcostumeÓ themselves like their environment, animals have been doing this for a long time. Spider crabs are one of the most interesting ones. These crabs cover their bodies with bits and pieces of sponges, seaweed, and other animals such as sea anemones, so when it is done with its costume it will look nothing more than the sea bed which it lives. These crabs have long slender legs which allow them to grab the material from around them and put it on their bodies. Many people theorized that their use of making was not intentional because certain creatures will grow on their shell. This was proved to be incorrect because if you were to remove this material, which is very lightly attached, the crab will become restless and search for new material to cover its body with. Also as the tide comes in and out the crab will change the types of material covering its body to more closely resemble its surroundings.
One very important technique that many animals use to camouflage themselves is the ability to remain completely motionless. This is known as freezing. Freezing works because of how the eye sees things. Even though the eye has the ability to pick things out of difficult situations sometimes it can overlook many details. For example if you were driving down the road and you passed some deer you may not necessarily see them, but if they moved then it would catch your eye making them more visible. An animal may have deceptive coloring and patterns; it may avoid having a shadow, but if any sudden motion is made may catch the eye of an observer. This is why the ability to remain completely motionless can be a very effective tool of many animals throughout the animal kingdom.
Newton was the first person to show that the suns rays were made up of different wavelengths of colors. The color of a body is due to the rays by which it is seen and not the body itself. Chemical coloring is one way that this takes place. When sunlight falls on a body some of the rays are absorbed while others are reflected. The pigments that were discussed earlier are what cause the absorption of these rays. Only certain wavelengths of the visible spectrum can be passed through the pigment. Some animals will use structural coloring. If a body scatters all the light that falls on it, the animal will seem to be white. Complete scattering is always the result of the random distribution of very small particles on the surface. The white in furs and feathers are resulting from the distribution of very small air bubbles between the fur and feathers.
Another type of camouflage is through resemblance. Camouflage through resemblance is not the same as mimicry which I will discuss later, but rather a special tool. Leaf resemblance is a type of resemblance that many animals will use. Since the area of the earth that is covered by green is extremely vast, many animals have adapted to resemble the greenery. Insects have a very easy time resembling leaves because of their wings. Since leaves are usually flat, have veins, and are round it is easily resembled by many insects. All the insects have to do is show their wings in profile and they can resemble leaves fairly easily. Resemblance of leaves are not isolated to insects, take for example the Òleaf fishÓ in South America. This type of fish will hang its head down beneath the surface of the water or lie flat on the bottom of the river looking like other dead leaves in the water. It is said that even when this fish is caught in a net it will remain completely motionless and many times wont be recognized as a fish, but rather thrown out being assumed to be a dead leaf. The oceans are an area where plant life can disguise animals very well due to the abundance of plant life. In areas that have abundant sea grasses there will be fish that resemble their swaying and slender leaves making them very difficult to spot. Pipefish for example will swim in a vertical position looking like a piece of sea grass. One of the most extraordinary examples of leaf resemblance is achieved by the animal known as the sea dragon. It has extremities that looks just like a fine weed and can be very hard to distinguish in light to heavily plant life.
Other than the resemblance of leafs there are animals that resemble bark and twigs. From insects to snakes there are animals that choose to flatten their bodies and look like the trees that they inhabit. Some snakes will have a flattened nose that will look like nothing more than a twig. Some animals will use leaf resemblance and twig resemblance as an aggressive type of camouflage. They will pretend to be a part of a tree and when their prey comes within striking distance they will do exactly that. Many times animals will come within touching distance of the predators without even knowing that they are in any type of danger.
A type of resemblance that is especially prominent in the marine realm is that of spare part resemblance. This is the action of making one part of your body look like another to help you evade predators. The butterfly fish for example will have a dark spot on its tail that resembles an eye. An attacker may be confused by the eyespot and mistake the tail for the head giving the butterfly fish a chance to evade in the opposite directions. On most fish that have the eyespot on their tail their head is disguised by deceptive markings and some people have reported seeing these fish swim backwards.
Color resemblance is a basic type of resemblance that is exactly how it sounds. Animals will adapt to resemble the colors of its environment. If you think about it every animal will resemble their environment in coloration. There are not any mammals that have green fur. This can be overcome by allowing organisms and plant life to grow on their body. For example the sloth will allow moss to grow on its back to help it blend in better with the rainforest top. This color resemblance between animals and their environment is known as homochromy. There are a few different types of special homochromy. The first is how animals will change their colors seasonally. Most seasonal color changes are due to the molting and replacement of hair or feathers by other of a new pattern. For the majority of examples, animals will have one coat during the summer and another during the winter. The changing climate allows them to adapt to their environment. During the winter the presence of fine air bubbles will even affect the color of their coat. The second special type of homochromy is the ability to have rapid color change. These quick color changes are present in fish, amphibians, lizards, cuttlefish, squid, shrimps and other types of crustaceans. Their ability to have rapid color change is due to their special cells called chromatophores. These cells have a branched cell with the pigment in its cytoplasm, the shape is constant but the pigment either fills all the branches, or concentrated in the center. This change in pigmentation will give the animal a colored or pale look. The number of pigments in one cell suggests there is a complicated structure within the cell. The most infamous animal that uses this type of color change is the chameleon. The chameleon can adjust to many different colors and hues depending on the environment that it is present. While some animals will use this type of color change as camouflage such as the chameleon, the squid uses its ability to change colors differently. Squids will change their colors to resemble their mood such as sexual excitement. Even though chameleons are the most infamous color changer, the flounder is the most extraordinary. Not only can flounder change their color they can change to match patterns. If placed on a black and white checkerboard pattern the flounder will change to match this. This is why the flounder is considered the most amazing color changer.
The most intense form of resemblance is the art of mimicry. More than art mimicry develops after many thousands of years of evolution. Mimicry is the imitation of the shape, color, and behavior of offensive or disgusting animals. MimicryÕs main purpose is to deceive the pursuer or prey. Batesian mimicry is now the term which refers exclusively to the imitation of offensive properties. Colors are a main type of avoidance mechanism. If an animal has bright colors, predators will often leave it alone due to the fact that it is probably poisonous. What some animals do is adapt and evolve to look like these poisonous animals. Mimicry is the ultimate form of resemblance because it takes thousands of years to develop; one animal will lose its individuality to become less tasteful to predators.
So far throughout this paper I have described all the different types of camouflage and what exactly each one is. I am now going to summarize the significance of camouflage. The effects of protective coloring are very important. There was a study done with Galapagos penguins and fish. The study consisted of putting two groups of fish, one in a white tank and one in a black tank. Then after the fish were allowed time to change colors an equal number were placed in an experimental tank, either black, in which the light fish were more conspicuous, or light gray where the dark fish were more conspicuous. Galapagos penguins were then allowed to try and catch them. The important thing that comes from this experiment are the results. Of the 2672 fish 1150 of them were caught. 395 of the fish caught were color adapted shad and 775 were of the non adapted shade. This experiment clearly proves the importance of color adaptation.
The place like San Salvador and the Florida Keys are excellent places to see everything that I have talked about in this paper. When walking around the seashore we will be able to see nearly every type of camouflage and mimicry in one form or another. The beach is an excellent place to see all different types of camouflage due to the adaptive nature of marine animals. While on a beach if you see a little flurry of sand, odds are you didnÕt imagine it, itÕs most likely a crab that has went into hiding. Along rocky coasts there will be animals firmly fasted to rocks that are nearly indistinguishable. Tide pools that we will be seeing on our workshop will be excellent areas to observe some of these adaptations. In these pools there will be things that look like plants, but this is a disguise for something more sinister. These flowers are meant to lure in fish and before they have a chance to escape they are devoured. Around these tide pools there will likely be spider crabs camouflaged with its surroundings, the master of masking. The sea shore is a great spot to actually get to visualize all these types of camouflage in one place.
The importance of camouflage in the wild can sometimes be over looked, and that is the point, to be over looked. The ability to recognize the act of camouflage is an essential part to understanding the ecosystem. When it comes to understanding camouflage and mimicry it takes patience. If you take time to sit back and take in the environment you will see many things you may have looked over in the past. Without camouflage animals would not be able to adapt to their environment and would become extinct due to either starvation or being consumed from predators. That is why I believe adaptation to ones surroundings is one of the most important traits that an organism can develop.

Works Cited
Cerullo, Mary M. The Octopus: Phantom of the Sea. New York: Cobblehill Books, 1997.
Ferrari, Marco. Colors for Survivial: Mimicry and Camouflage in Nature. Charlottesville: Thomasson-Grant, 1992.
Fogden, Michael, and Patricia Fogden. Animals and Their Colors. New York: Crown Inc., 1974.
Portmann, Adolf. Animal Camouflage. Michigan: University of Michigan P, 1959.
Shuttlesworth, Dorothy. Animal Camouflage. New York: The Natural History P, 1966.

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