Animal behaviors, Biology, Black Grouse, Charles Darwin, Evolutionary Mechanisms, Evolutionary Quotes, Image, Natural Selection, On The Origin Of Species, Origin of Species, Predation, Red Grouse, Text, Zoology
“When we see leaf-eating insects green, and bark-feeders mottled-grey; the alpine ptarmigan white in winter, the red-grouse the colour of heather, and the black-grouse that of peaty earth, we must believe that these tints are of service to these birds and insects in preserving them from danger. Grouse, if not destroyed at some period of their lives, would increase in countless numbers; they are known to suffer largely from birds of prey; and hawks are guided by eyesight to their prey, so much so, that on parts of the Continent persons are warned not to keep white pigeons, as being the most liable to destruction. Hence I can see no reason to doubt that natural selection might be most effective in giving the proper colour to each kind of grouse, and in keeping that colour, when once acquired, true and constant.”
“On The Origin Of Species, 1859″
There is a strong evolutionary pressure for animals to blend into their environment or conceal their shape, for prey animals to avoid predators and for predators to be able to avoid detection by prey. (Exceptions include large herbivores without natural enemies, brilliantly-colored birds that rely on flight to escape predators, and venomous animals that advertise with bright colors.) Cryptic animals include the tawny frogmouth (feather patterning resembles bark), the tuatara (hides in burrows all day; nocturnal), somejellyfish (transparent), the leafy sea dragon, and the flounder (covers itself in sediment).
In evolutionary ecology, crypsis is the ability of an organism to avoid observation or detection by other organisms. It may be either a predation strategy or an antipredator adaptation, and methods include camouflage, nocturnality, subterranean lifestyle, transparency, and mimicry. The word can also be used in the context of eggs and pheromone production.
In evolutionary biology, mimicry is the similarity of one species to another which protects one or both. This similarity can be in appearance, behaviour, sound, scent and even location, with the mimics found in similar places to their models. Mimicry occurs when a group of organisms, the mimics, evolve to share common perceivedcharacteristics with another group, the models. The evolution is driven by the selective action of a signal-receiver, or dupe. For example, birds that use sight to identify palatable insects (the mimics), whilst avoiding the noxious models.
Many animals have evolved so that they visually resemble their surroundings, using some sort of natural camouflage that may match the color of the surroundings (cryptic coloration) and/or break up the visual outline of the animal itself. Such animals may resemble rocks, sand, twigs, leaves, and even bird droppings.
Camouflage, in which a species resembles its surroundings, is essentially a form of visual mimicry. In between camouflage and mimicry is mimesis, in which the mimic takes on the properties of a specific object or organism, but one to which the dupe is indifferent. The lack of a true distinction between the two phenomena can be seen in animals that resemble twigs, bark, leaves or flowers, in that they are often classified as camouflaged (a plant constitutes its “surroundings”), but are sometimes classified as mimics (a plant is also an organism). Crypsis is a broader concept which encompasses all forms of avoiding detection, such as mimicry, camouflage, hiding etc.
- Fake caterpillars’ camouflage clue (bbc.co.uk)
- Adaptation of an Animal: Camouflage (ahschoolapbio2013.wordpress.com)