COLOUR STRATEGIES IN NATURE ABOUT THE USE OF COLOUR IN NATURE STRATEGIES BETWEEN MIMICRY AND PROTAGONISM a text by Francesca Cremasco MIMICRY / CAMOUFLAGE / IMITATION The word ‘mimicry’ is derived from the Greek ‘mimetizo’ which means ‘imitation’. In nature it indicates the phenomenon in which an animal takes colours, forms, behaviors and other characteristics to be similar to the environment around it, or to another animal. Mimicry is one of the most interesting and complex phenomena within environment adaptations aimed at survival. If an individual does not adapted to the environment in which it lives, its chances of survival and reproduction are minimal. A very similar colour to the surrounding environment is beneficial in escaping predators, but also to avoid being noticed by an animals’ potential victims. Body color is often linked to the needs of the struggle for existence. Animals may have two types of camouflage, one with the aim to hide (survival, protection) and the other with the aim of modifying appearance and recognition (predation and reproduction).
The first is known as cryptic mimicry (from the Greek kriptòs = hidden) and refers to the process of a subject physically adapting to its surrounding environment, or becoming part of it, in order to hide or become invisible. Some animals authentically mimic the colors and the shapes of leaves, flowers, wood or rocks. The second type is known as the faneric mimicry (from the Greek phaneros, manifest) and occurs when an advantageous feature is “copied” from other species for predation. Faneric mimicry may be ‘batesian’ and ‘müllerian’. With batesian mimicry (the name derives from Henry Bates who first discovered and reported this phenomenon) a harmless species is protected by its resemblance to one or more dangerous species, noxious or unattractive. This type of mimicry functions as a defensive strategy. This type of system may evolve if models and mimes coexist in time and space, and share a similar lifestyle. With mullerian mimicry (from Fritz Mulller) two or more species assume similar shapes and colours in order to not be distinguishable, and thus by having similar colors predators quickly learn to chase both. Such “cooperation” allows a mutual advantage to these species, as the predators must learn only one signal. In this way every single species is preyed on in smaller quantities. FUNCTION / TYPES OF STRATEGIES In order to understand mimicry in its true sense, it is important to look at each function of the various camouflage types, and their effects . The function connects and organizes all the parts into a system and identifies a strategy. Each part (such as the form, colour, motion etc.) can have different meanings depending on the specific context of relationships. This is crucial because similar pattern types (e.g. blotches, stripes) may have entirely different functions in different animals and circumstances, ranging from camouflage to warning and sexual signals. The main forms of visual camouflage1: Background matching: where the appearance generally matches the colour, lightness and pattern of one (specialist) or several (compromise) background types. When a subject has the same color (monochromatic) as its environment there is an identification of figure and background (examples are frogs, caterpillars etc. ...). This process can happen even with the borrowing of materials from a context (like fish camouflaged in the sand). Another example is when the livery matches several background types. This can happen in two ways, one considers the subject and its environment (like a leopard in the savannah), the second regards a group of subjects rather than the individual. This difference leads to specific configurations of livery. In the first case the pattern takes colours and forms from the surrounding context, but in the second case the pattern performs its function through the dynamics of the group, through the multiplication of subjects. For example, the striped pattern of the zebra produces an optical illusion, which makes it difficult to recognize the single subject. The “disguise” is optimized not only for the environment but also for group behavior of herd animals. Counter shading (obliterative shading and self‐shadow concealment): a counter‐shaded animal possesses a darker surface on the side that typically faces greater light intensity and a lighter opposite side. Counter shading appears to be involved in several functions, including the compensation of the animal’s own shadow (self‐shadow concealment), simultaneously matching two different backgrounds in two different directions (background matching), changing the three‐dimensional appearance of the animal (obliterative shading). In self‐shadow concealment the creation of shadows is cancelled out by counter shading, and obliterative shading, where the creation of shadow/light cues for the three‐ dimensional form of the animal are destroyed. Disruptive coloration: being a set of markings that creates the appearance of false edges and boundaries, which hinders the detection or recognition of an object’s, or part of an object’s, true outline and shape. A typical example is a body coloration that consists of high‐contrast markings that tend to break up the appearance of an animal.
1 Here the term camouflage is used to describe all forms of concealment, including those strategies preventing detection (crypsis) and those recognition (e.g. masquerade).
Flicker‐fusion camouflage: where markings such as stripes blur during motion to match the colour/lightness of the general background, preventing detection of the animal when in motion. Distractive markings: which direct the “attention” or gaze of the receiver from traits that would give away the animal (such as the outline). Transparency: where part of an animal’s body is transparent, reducing the likelihood that it will be detected. Silvering: common in aquatic environments and where an animal’s body is highly reflective (like a mirror) making it difficult to detect when light incidence is non‐directional (such as due to strong scattering by water‐borne particles). Masquerade: prevents recognition by resembling an uninteresting object, such as a leaf or a stick. Motion dazzle: markings that make estimates of speed and trajectory difficult by the receiver. Motion camouflage: movement in a fashion that decreases the probability of movement detection. An animal appears to be stationary, ‘tricking’ the receiver’s visual system by moving in a certain way. MAIN ASPECTS The first important aspect of mimicry is the function (what it does), which is resolved through the synergy of many different matters. The technical aspect of visual camouflage provides a specific solution to a desired function. Function always moves from some foundational aspects. The first and foremost is communication, the need to transfer a message. The color is the most effective mean to communicate and create an emotional state (attraction, fear, protection, etc.). This fact implies the involvement of at least three subjects : an active subject, a passive subject (receiver) and the environment, and each subjects can be single or a group. The first two subjects are involved in an empathic relation and the space is used passively, it has a role of utility. The result is always a relation, which stems from the specific needs and characteristics of the subjects. Mimicry processes occur in a space and generate a space (of relations, of attraction, of warning etc.). What happens during the process is perceived only by subjects involved, or by external parties capable of decoding the phenomenon, therefore of having the same cognitive abilities. The strategy of imitation in nature is based on the existence of a model, an imitator and a receiver (the subject deceived by the imitator). This process is in continuous evolution because the imitator tends towards a complete imitation of the model, and the receiver evolves towards an increasingly accurate distinction of the characteristics of the imitator. The cognitive abilities of the receiver are constitutive part of the process of mimesis. In the process of natural selection what is decisive is the viewer’s perception, not our own, because it has created the selection pressure on the animal’s coloration. bibliography: Animal camouflage, edited by M. Stevens and S. Merilaita, Cambridge University Press, 2011 Exploring Life Set, G.Brum, L. K. McKane, G. Karp, Wiley & Sons, Canada, 1994 Il mimetismo animale, Ward P. , De Agostini, Novara, 1979 web resources: http://en.wikipedia.org/wiki/Mimicry http://en.wikipedia.org/wiki/Animal_coloration
example of cryptic mimicry
time adaptation to the environment may be contingent
colour, form and pattern
colour some examples of background matching.
optical illusion - false eyes Large spots that resemble eyes is a frequent drawing on the coat of animals. Simulate parts of the body in different positions serves to look bigger and scare the predator.
example of faneric mimicry
false identity Small differences on colour and pattern for appear how other species,
in a defensive strategy
Some animals take the appearance of dangerous animals for intimidate predators. In other cases the strategy is the opposite. Some predators mimic the prey (usually the female) for approach it
CONTACT POINT POSSIBLE MIGRATION OF FUNCTIONS AND TECHNIQUES The concepts outlined above may suggest new perspectives on our environment. Changing one’s approach leads to a reinterpretation of the places that belong to a vision almost codified, but also suggests ways for defining new functions and relationships. Below I want to suggest some architectural aspects of mimetic processes, and how they could lead to new territories of experimental design. With regards to the spatial qualities of mimetic processes, in many cases we can see that the active subject aims to simulate “other” spatialities (of the background, of the surrounding elements), or to conceal its three‐dimensionality. It’s a sort of dematerialization and depersonalization, in order to assimilate the characteristics of spaces surrounding the subject, through a complex flattening process. Background matching, countershading, disruptive coloration, flicker‐fusion camouflage, transparency, silvering and masquerade all fall under this category. The constant element in these processes is the interaction between active subject and the background or surrounding space. The active subject adapts itself to an environment that is used in a passive way. Changing point of view, the subject is always in relation with surfaces, even if the interaction is not functional and not designed. In mimicry, the colours and forms of livery are the most important elements, supported also by the orientation of subject and the arrangement of its body parts in space. Their position is linked to the point of view of the receiver, which can be directed in particular either to the horizontal (from top to bottom), or to vertical planes (from high to low). The quality of surfaces (colours, shapes, developed along a dominant axis) has an important role on perception of dimension ‐real, dilated or restricted. As explained above, in nature the relationship status, determined by the specificity of the subject (defensive, aggressive, attraction etc.), is the driver of the form of mimicry. In other words the type of relationship is the driving force of the project. Shifting the concept to architecture, project development and design, relationships of various natures could emerge, i.e. elements, people, places, and thus influence people’s reactions and behavior in relation to the various functions. Position and behavior are two closely related concepts, not only in the animal world. The arrangement of subjects creates spatialities with different characteristics. Spaces of proximity, attraction or repulsion are generated through location and orientation. The communication assets of colour helps to define the quality of the movement between the parts, attraction, repulsion or distance. A signal of danger induces a user to keep his or her distance and vice versa, attractive colours induce rapprochement. The qualities of the livery interact on the perception of the receiver, creating a conditioned view. Strips, patches, “decorative” motifs guiding vision, sometimes cause a “distorted” perception, but correspond exactly to the required function.
SUGGESTIONS case_1 relation subject/background/ movement
In the subway there are spaces allocated to different functions (spaces where people walk and spaces for waiting) but usually the aspect does not change. Surfaces are the background of these conditions. Rethinking the surfaces as places of interaction with figures could lead to new scenarios and a new territory of exploration.
countershading/orientation of surfaces
This type of situation is very common in urban places. The rear side of road platforms, tramlines or trains is a horizontal surface which dominates the environment. A different treatment of these could affect the perception of spatiality. Acting on perception means acting on space. Urban margin spaces could be converted to places of many different functions or just evolve into something suitable for human environment.
Road barriers are a visual protection (to hide the road from the surrounding environment) and anti‐noise filter (cushion the impact of traffic noise). Their condition is double (internal/external) in fact the perception and the utility is differently from inside and outside the street. The aspect of surfaces could be designed for extend functionality. Through acting on shapes and colors of surfaces it is possible to determine a type of perceptual relationship (concealment, decorative, communicative) . Outside the receiver could be near or far, standing still or in motion. This fact changes the possible function and consequently the form of decoration (away from the barrier may indicate the presence of the road giving useful information, but closely the decoration can be viewed in a different way).
case_4 affect the perception/re‐semantise
In many buildings the appearance of the facade is dominant in urban spaces. There are many facades designed with visual codes now exceeded. Acting on their appearance we could transform and deform the perception we have on them. Modifying figures, forms, colors, rhythms, it is possible to guide the perception to something different without destroying the existing. Nature provides us with methodological examples and concepts (like distractive markings, disruptive coloration etc.) so we can come up with new case_5 techniques.
extend the functions/space in the shadows
Animals use shadow to change the perception of their volume or to disappear. In many cases (as in historical places) we need to make invisible interventions or minimize the impact on the existing elements. The relation of light‐shadow on architecture is of primary importance, rarely do we look at the shadow before we look at the building thus not exploring the visual opportunities and signals of shadows. Through shadows it is possible to re‐think spaces, equipment, roofing and many other typologies of elements which may cause shadows to hide, to confuse, to emphasize surrounding elements.
case_6 emotional perception of space/figure‐background
Pedestrian underpasses should be visible, attractive and perceived as safe, the opposite of what often happens. Visibility of subjects outside and during the passage is the most important aspect of feeling safe in a place. This case has an analogy with background matching, the one about relation between subject and background. Light‐shadow and colors are the primary elements upon which we can work to influence the perception of underpasses.
Different conditions/functions coexist in the same. The relation figure/ background can help isolate the subject from its surroundings and amplify the attention to it. Concentration is the most important aspect when we are talking with somebody for a few minutes in a public office. Also the division of spaces (not only physical but also sensory‐perceptual) is important for both conditions (waiting and action). During moments of concentration, the space tends to lose its three‐dimensionality. Visual perception focuses on the close up. Also the acoustic isolation, which is very important in terms of concentration, deletes the perception on three‐dimensionality of space. Space planning should lead to a correct spatial relationship (proximity, distance), not only physical but also perceived.
CONCLUSION Mimicry is a complex phenomenon that must be analyzed from many points of view, because simple and different elements become the visual reply of complex interactions. Mimicry is a system of environmental adaptation, which from time to time finds unusual functional expressions. The function is the place where elements are organized in a strategy, which is the expression of characteristics and relations between the subjects involved in the mimetic process. The subjects are of primary importance because they are the driving of the system. Every animal is an active and passive subject at the same time, because each subject can be predator or prey for another subject. Mimicry primarily serves in situations of conflict, where there is a contraposition of interest between individuals. The conflict take place if the interest of a subject (active) precludes/conditions the interest of the other (passive subject). Our environment (not only natural but also our built environment) has many places of contrast, some of which are not immediately identifiable because of our ordinary vision. We often suffer the surrounding reality because we take for granted the modalities that have generated it. Many places, spaces, and elements that appear neutral to our vision are instead actually strongly characterized. Mimicry often seems neutral, because of the visual depersonalization of the subjects on the environment. It's a form of highly engineered neutrality. Can harmonious coexistence come through a neutral project? As social animals, which mechanisms can we actuate to adapt the environment to many different users? Also, how could we be more adaptable to our current environmental circumstances? In conflict conditions, which are the mimetic strategies that we normally use, and how much can our intervention influence the environment? Since our world is so strongly artificialized, is it still possible to refer to a natural world and adopt its strategies?