Camouflage and Mimicry

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Contents 1 Definition 2 Types of mimicry 3 Types of camouflage 4 Evolution of camouflage and mimicry 5 Related Articles

[edit] Definition

Mimicry, in biology, is one species having traits which makes it look like another; camouflage is a species having traits which make it look like its habitat.

[edit] Types of mimicry

• Batesian mimicry is where a harmless species (e.g. a hoverfly) resembles one which has chemical or mechanical defenses (e.g. a wasp).

• Müllerian mimicry is like Batesian mimicry except that the two species mimicking one another are both poisonous or unpalatable. Both species benefit from this, because each reinforces the message that their common appearance is dangerous. This might be seen as a very weak form of symbiosis.

• Peckhamian mimicry is the use of mimicry as a lure to attract prey. For example, species such as angler fish or snapping turtles use parts of their body to imitate worms or other small prey, to attract small predators which they then eat.

• Bakerian mimicry is mimicry to attract pollinators; the most spectacular example is the bee orchid (pictured to the right).

• Vavilovian mimicry is the evolution of a wild species to look like one cultivated by artificial selection, in order to avoid being weeded out by cultivators.

• Automimicry is the mimicry of one part of an animal's body by another, most usually a tail which looks like a head, confusing the casual observer as to which way its facing.

[edit] Types of camouflage

• Color camouflage : The most obvious form of camouflage is simply for a species to have a color similar to the background it's usually found against.

• Pattern camouflage : Spots, stripes, and speckles are also useful forms of camouflage, because they confuse the visual cues of light and shade which we use to pick out three-dimensional objects from their surroundings.

• Counter-coloration : A similar adaptation, known as counter-coloration, is to be dark on top and light below. Because animals are lit from above, counter-coloration cancels out the visual cues which could otherwise be used to pick the animal out as a three-dimensional object.

All these methods of camouflage have been adopted for use by the modern military.

[edit] Evolution of camouflage and mimicry

The evolution of camouflage and mimicry appears puzzling to many people, especially creationists, who are good at being puzzled by biology. What puzzles them is how these phenomena can evolve gradually. It is easy to see why it is advantageous to look like a leaf, but not how it's advantageous to look a bit like a leaf.

The solution to this apparent puzzle is to note that camouflage need not be totally convincing to be useful. Soldiers' camouflage doesn't make them look very like vegetation, but at a distance, or in partial cover, or when visibility is poor, it gives the wearer a distinct edge over, for example, the British redcoats of the eighteenth century. In the same way, a very imperfect camouflage is still useful to a creature in twilight, or in partial cover, or glimpsed out of the corner of a predator's eye, or seen at a distance. Any slight variation which conceals the prey from the predator under slightly better visual conditions will be advantageous and therefore favored by natural selection. So, too, in the case of mimicry, a flash of yellow on an insect seen at a distance might be enough to suggest a wasp, and deter predators; the closer the resemblance to a wasp, the closer a predator needs to be to see through the deception.

Hence, camouflage and mimicry are not all-or-nothing affairs: any such tendency, however slight, carries with it a slight selective advantage.

[edit] Related Articles

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