Adaptive Coloration in Animals
OCLC 974070031 | |
Adaptive Coloration in Animals is a 500-page textbook about
The book's general method is to present a wide range of examples from across the animal kingdom of each type of coloration, including marine invertebrates and fishes as well as terrestrial insects, amphibians, reptiles, birds and mammals. The examples are supported by many of Cott's own drawings, diagrams, and photographs. This essentially descriptive natural history treatment is supplemented with accounts of experiments by Cott and others. The book had few precedents, but to some extent follows (and criticises) Abbott Handerson Thayer's 1909 Concealing-Coloration in the Animal Kingdom.
The book is divided into three parts: concealment, advertisement, and disguise. Part 1, concealment, covers the methods of camouflage, which are colour resemblance,
Cott's textbook was at once well received, being admired both by zoologists and naturalists and among allied soldiers. Many officers carried a copy of the book with them in the field. Since the war it has formed the basis for experimental investigation of camouflage, while its breadth of coverage and accuracy have ensured that it remains frequently cited in scientific papers.
The book
Approach
Adaptive Coloration in Animals is a 500-page book, 10 by 7 inches (250 by 180 mm) in its first edition. It was published by Methuen (in London) and Oxford University Press (in New York) in 1940. It is full of detailed observations of types of camouflage and other uses of colour in animals, and illustrated by the author with clear drawings and photographs. There is a coloured frontispiece showing eight of Cott's paintings of tropical amphibians. The book has 48 monotone plates and several illustrations.[P 1]
Cott's method is to provide a large number of examples, illustrated with his own drawings or photographs, showing animals from different groups including fish, reptiles, birds and insects, especially butterflies. The examples are chosen to illustrate specific adaptations. For example, the fish
this species had the habit of swimming very slowly tail first: but when disturbed it darts rapidly off to safety in the opposite direction... C. capistratus adopts the same tactics... [This fish] is of particular interest in that the real eye is obliterated and a false eye substituted in one and the same animal.
— Hugh Cott[P 2]
Cott was well aware that he was publishing in wartime. There are, as
Structure
The book addresses its subject under three main headings: concealment, advertisement, and disguise.
Part I: Concealment
- The methods by which concealment is attained in nature
Cott sets out his view that we have to be re-taught how to see, mentioning Ruskin's "innocence of the eye". He argues that camouflage should, and in animals actually does, use four mechanisms: colour resemblance, obliterative shading (i.e. countershading, the graded shading which conceals self-shadowing of the lower body), disruptive coloration, and shadow elimination.
Chapter 1. General colour resemblance.
- Cott gives many examples such as a table of 16 species of green tropical tree-snakes.
Chapter 2. Variable colour resemblance. Caterpillars and pupae (as in Poulton's famous experiment) are coloured to match their environment. Mountain hares change colour in winter; many fish, cephalopods, frogs, and crustacea can change colour rapidly.
Chapter 3. Obliterative shading.
- Following the artist and amateur naturalist Abbott Handerson Thayer, Cott explains countershading with diagrams, photographs of models and examples of real animals. He shows how helpful it would be for military camouflage with drawings of gun barrels.
Chapter 4. Disruptive coloration.
- Cott argues with diagrams, drawings, photographs and examples that animals are often extremely effectively disruptively patterned. He analyses the component effects of disruption, including "differential blending" and "maximum disruptive contrast". Cott's figure 7 is a set of nine drawings, arranged as a 3x3 table. On the left is an animal's outline in grey tone against a differently coloured background. In the centre, the same animals are now disruptively patterned against the same plain backgrounds. On the right, the disruptively patterned animals are shown against realistic broken backgrounds containing vegetation or rocks. Cott explains
The simplified diagrams in Fig. 7 illustrate the value and effectiveness of maximum disruptive contrasts better than any verbal description... On looking at these drawings from a little distance, it will be seen that the conspicuous patches operate most efficiently in distracting attention from the form of the animals wearing them. By sheer force of their brightness, or blackness, or contrasts, they dominate the picture presented to the eye, apparently destroying their form...[P 5]
Cott goes on to explain that the right-hand drawing shows the effect "of broken surroundings in further blending and confusing the picture",[P 5] observing that this is the closest to what is seen in nature. His readers are invited to look first at the right-hand images to gain an idea of the power of "these optical devices" as camouflage, putting off the moment when the animal is actually recognised.[P 6]
Chapter 5. Coincident disruptive coloration.
- Animals such as frogs are patterned so that when they are at rest with legs tucked in, their outline is powerfully disrupted with markings that seem to flow across body and leg boundaries. Eyes too are often hidden in stripes or eye masks.
Chapter 6. Concealment Of the shadow.
- Cast shadows give away even well-camouflaged animals. Many animals therefore take care to minimise shadow, by lying down, with flattened bodies, or with fringes. Some hawkmoth caterpillars have false shadow patterns to suggest they are parts of other objects.
- The function of concealing coloration in nature
Chapter 7. Concealment in defence, mainly as illustrated by birds.
- Cott considers how effective camouflage is as an adaptation, such as in incubation and rest (sleep) in birds. For instance nightjars are nocturnal, and rest, well camouflaged, on the ground during the day.
Chapter 8. Concealment In offence.
- Cott describes the care that predators take when approaching prey, minimizing visible movement and scent, the use of cover for ambush, and "adaptive silence".
Chapter 9. Objections and evidence bearing on the theory of concealing coloration.
- In this chapter Cott discusses various objections to the adaptive (evolutionary) nature of camouflage, and provides evidence to dismiss them. Some are "based upon such obvious fallacies that they hardly deserve serious consideration."
Chapter 10. The effectiveness of concealing coloration.
- Cott describes simple experiments such as that fish that have changed colour to match a pale background survived better (64% to 42%) on such a background than fish which had not. He also quotes some anecdotal observations on wild animals with similar but not quantified results.
Part II: Advertisement
- The methods by which conspicuousness is attained in nature
Chapter 1. The appearance and behaviour of aposematic animals.
- Animals that are genuinely distasteful (aposematic) boldly advertise themselves in black, white, red, and yellow. They are often "sluggish", not running from predators; gregarious; and diurnal, since warning displays only work if they can be seen "by potential enemies".[P 7]
Chapter 2. Warning displays.
- Aposematic animals often have (Chlamydosaurus kingii, is illustrated in a drawing by Cott, with its tail raised over the body, stretched up on all four legs, mouth wide open, and frills out both sides of the head, making it a startling sight.
Chapter 3. Adventitious warning coloration.
- Some marine animals select aposematic materials as coverings, not only as camouflage. Some birds nest near wasps' nests.
- Warning coloration in relation to prey
Chapter 4. The nature and function of warning coloration, as illustrated by the mammalia.
- Prey like porcupines have warning colours, make noise, and attack predators (even leopards).
Chapter 5. The Protective Attributes Of Aposematic Animals In General.
- Evidence is given that conspicuous animals such as caterpillars really are distasteful. Animals with actual poisons are discussed, and how these are secreted, used in bites and stings, or kept to make the animal bitter tasting.
Chapter 6. The relation between warning colours and distasteful attributes.
- Various kinds of evidence are presented for aposematism.
Chapter 7. The effectiveness of protective attributes associated with warning colours.
- Experimental evidence is presented that insects with warning colours are rejected by predators.
- Warning coloration in reference to predatory enemies
Chapter 8. Experimental evidence that vertebrate enemies learn by experience.
- Experiments by Cott show that toads learn to avoid eating stinging bees.
Chapter 9. Evidence of selective feeding by vertebrate enemies in a state of nature.
- Evidence from wild birds and toads demonstrates preferences for particular prey.
Part III: Disguise
- Special protective and aggressive resemblance
Chapter 1. Special resemblance to particular objects.
- Cott describes leaf-like fish, chameleons, and insects, and other mimetic forms of camouflage. A liana-like snake near Para (a haunt of Naturalist on the River Amazons) 160 times as long as it was thick is called "a revelation in the art of aggressive resemblance".
Chapter 2. Adaptive behaviour in relation to special cryptic resemblance.
- Animals keep still, sway in the wind, or play dead to assist their camouflage. Poulton's examples of twig-like Nyctibius griseus, sitting on its nest mimicking a broken branch. Cott explains, in a section on "Special resemblances in relation to the attitude of rest"
This wonderful bird ... habitually selects the top of an upright stump as a receptacle for its egg, which usually occupies a small hollow just, and only just, large enough to contain it.... the stump selected had thrown up a new leader just below the point of fracture;... the bird sat facing this in such a way that when viewed from behind they came into line and blended with the grey stem.[P 8]
Chapter 3. Adventitious Concealing Coloration.
- Cott begins by citing Shakespeare's Macbethwith "until/ Great Birnamwood to the Dunsinane hill/ Shall come against him" to introduce his chapter on the use of materials as camouflage. Animals from crabs to caterpillars are described.
- Conspicuous localized characters
Chapter 4. Deflective marks.
- Cott describes markings that help to deflect attack, such as the eyespots of butterfly wings and the twitching cast-off tails of lizards, both acknowledged to Poulton,Natural History and Antiquities of Selborne.[P 10]
Chapter 5. Directive marks.
- A selection of lures and deceptive markings are described. A large drawing depicts the Chaetodon capistratus, the four-eye butterfly fish, which are "usually towards the tail end" and tending to direct attack away from the head.[P 11]
- Alluring and mimetic resemblances
Chapter 6. Alluring coloration.
- The bird-dropping spider Hymenopus bicornisand other camouflaged hunters are described.
Chapter 7. Mimicry: the attributes of mimics.
- Cott follows Poulton in treating mimicry as basically the same as camouflage or "adaptive resemblance". Mullerian mimicryare compared. The behaviour of "Esquimaux seal-hunters" and First World War Q-ships are mentioned.
Chapter 8. Breeding parasitism and mimicry in cuckoos.
- The mimicry and behaviour of the European cuckoo, Cuculus canorusis analysed.
Conclusion
The final chapter confirms that "The force of the facts and arguments used in this work is cumulative in effect." Many small steps of reasoning combine to show that "adaptive coloration... has been... one of the main achievements of organic
Reception
Foreword
Dr. Cott, in this important book, has turned the tables with a vengeance on objectors of this type... Had they taken the trouble to acquaint themselves with even a fraction of the relevant facts to be found in nature, they could never have ventured to enunciate such sweeping criticisms: their objections are a measure of their ignorance.
— Julian Huxley[P 12]
With objections dismissed, Huxley remarks that "Dr. Cott is a true follower of Darwin in driving his conclusions home by sheer weight of example," observing that "Faced with his long lists of demonstrative cases, the reader is tempted to wonder why adaptive theories of coloration have been singled out for attack by anti-selectionists." Huxley also noted Cott's "constant cross-reference to human affairs", and that it was good to know that Cott was applying his principles "to the practice of camouflage in war".[P 12]
Huxley concluded his introduction by describing Adaptive Coloration as "in many respects the last word on the subject", upholding the great tradition of "scientific natural history".[P 12]
Contemporary reviews (circa 1940)
Reviewers had little to compare Adaptive Coloration with. The English zoologist
This excellent work, eagerly awaited for many years, will be most welcome to naturalists, even, we may hope, to the few who have hitherto rejected the Darwinian interpretation which the author has here supported by a mass of additional evidence based on his own observations and those of very many others.
— E.B. Poulton[4]
The
In this Neodarwinian epic Dr. Cott stamps himself as a true disciple of the master evolutionist. Indeed, he rivals Darwin in the thorough, objective and penetrating analysis of a major biological problem. An immense body of facts and interpretation, much of it original, has been judiciously considered and brought to bear on the question of the biological significance of coloration.
— Carl L. Hubbs[5]
Hubbs notes that Cott is seeming concerned about the scarcity of experimental data for the survival value of camouflage, and accordingly relies on Sumner and Isely's "clear-cut results", but at once continues that Cott relies on "the general lore of natural history". Hubbs also remarks on the "resurgence to Darwinian views", referring to the scepticism about the power of natural selection among both geneticists of the time and to the Lamarckist views of Trofim Lysenko.[5]
Hubbs observes that Cott is both an artist and a naturalist as well as a scientist: "In section after section, rivaling one another in fascination, this master of art and of natural history unfolds the biological significance of adaptive coloration in animals." And Cott's emphasis on disruptive patterning and (following Thayer) countershading clearly affected the reviewer: "Particularly impressive is the author's treatment of "coincident disruptive coloration", in which a ruptive mark crosses structural boundaries, so as to obliterate visually such ordinarily conspicuous parts as the eye and the limbs. Concealment of an animal's ordinarily telltale shadow is also stressed". Hubbs's review ends "This book is the work of an artist, and it is a work of art. Every biologist with an interest in any phase of natural history or evolution should keep it at hand."[5]
"W.L.S.", reviewing Cott in The
Looking back (after 2000)
Peter Forbes, in his book Dazzled and Deceived, wrote that[7]
Cott's Adaptive Coloration in Animals must be the only compendious zoology tract ever to be packed in a soldier's kitbag. The book also marks the apotheosis of the descriptive natural history phase of mimicry studies. Although Cott does report experiments on predation to test the efficacy of mimicry and camouflage, the book is essentially a narrative of examples plus theory.[7]
Over 60 years after its publication, Adaptive Coloration in Animals remains a core reference on the subject. Sören Nylin and colleagues observe in a 2001 paper that
Adaptive coloration in animals has been a very active research field in evolutionary biology over the years (e.g. Poulton 1890, Cott 1940, Kettlewell 1973, Sillen-Tullberg 1988, Malcolm 1990), and one in which the Lepidoptera have always featured prominently as model species.
— Sören Nylin[8]
As a natural history narrative on what has become an intensely researched experimental subject,[9] Adaptive Coloration could be thought obsolete, but instead, Peter Forbes observes "But Cott's book is still valuable today for its enormous range, for its passionate exposition of the theories of mimicry and camouflage".[7] This width of coverage and continuing relevance can be seen in the introduction to Sami Merilaita and Johan Lind's 2005 paper on camouflage, Background-Matching and Disruptive Coloration, and the Evolution of Cryptic Coloration, which cites Adaptive Coloration no fewer than eight times, quoting his terms "cryptic coloration or camouflage", "concealing coloration", "background matching (also called cryptic resemblance)", "disruptive coloration", resemblance to visual background, and the difficulty a predator has to detect a prey visually.[10]
Steven Vogel, in a review of Peter Forbes's book Dazzled and Deceived (2009), echoes Julian Huxley's words of seventy years before (in his 'Introduction')[P 12] by writing
The zoologist Hugh Cott had the final word in Adaptive Coloration in Animals (1940), a definitive synthesis of everything known about
Biomimetic camouflage took its place as yet another technique in a sophisticated armamentarium of visual deceptions.[11]
Camouflage researcher Roy Behrens cites and discusses Adaptive Coloration frequently in his writings. For example, in his Camoupedia blog, related to the book of the same name,[12] he writes of Cott's drawings of the hind limbs of the Common frog: "Reproduced above is one of my favorite drawings from what is one of my favorite books." He continues "What makes these drawings (and the book itself) even more interesting is that Cott (1900-1987) was not just a zoologist—he was a highly skilled scientific illustrator (these are his own pen-and-ink drawings), a wildlife photographer, and a prominent British camoufleur in World War II." Still in 2011, Behrens can write of Cott's way of thinking, citing his words as models of clear and accurate explanation of the mechanisms of camouflage: "As he so aptly explained it, disruptive patterns work 'by the optical destruction of what is present', while continuous patterns work 'by the optical construction of what is not present.'"[13]
Publication history
Adaptive Coloration in Animals has been published as follows:
- 1940, Methuen, Frome and London (printed by Butler and Tanner). Foreword by Julian Huxley
- 1940, Oxford University Press, New York
- 1941, Oxford University Press, New York
- 1957, Methuen, London (reprinted with minor corrections)
- 1966, Methuen, London (reprinted with minor corrections)
See also
- Concealing-Coloration in the Animal Kingdom (G. H. Thayer, 1909)
- E. B. Poulton, 1890)
- F. E. Beddard, 1892)
References
Primary
Secondary
- ^ Rothenberg, David (2011). Survival of the Beautiful. Bloomsbury. p. 167.
- ^ a b Shull, A.F. Evolution. McGraw-Hill, 1936. pp175, 212.
- ^ Poulton, 1890.
- ^ Poulton, 1940.
- ^ a b c Hubbs, 1942. pp 318-321.
- JSTOR 1788577.
- ^ a b c Forbes, Peter. (2009) Page 153.
- ^ Nylin, Sören; Gamberale-Stille, Gabriella; Tullberg, Birgitta S. (2001). "Ontogeny of Defense and Adaptive Coloration in Larvae of the Comma Butterfly, Polygonia C-Album (Nymphalidae)" (PDF). Journal of the Lepidopterists' Society. 55 (1): 69–73.
- PMID 16959630.
- PMID 15817442.
- ^ Behrens, 2009.
- ^ Behrens, Roy R. (13 December 2011). "Hugh B. Cott - Zoologist and Camoufleur". Camoupedia. Retrieved 15 November 2012.
Bibliography
- Behrens, Roy R. (2009). Camoupedia: A Compendium of Research on Art, Architecture and Camouflage. Bobolink Books. ISBN 978-0-9713244-6-6.
- Cott, Hugh B. (1940). Adaptive Coloration in Animals. Methuen.
- Forbes, Peter (2009). Dazzled and Deceived: Mimicry and Camouflage. Yale.
- doi:10.1086/281046. Archived from the originalon 2013-01-16. Retrieved 2012-11-16.
- S2CID 4114423.
- Poulton, Edward B. (1890). The Colours of Animals. London: Int. Sci. Ser. LXVIII.
External links
- Ohio State University: The Camouflage Project: Hugh Cott
- Smithsonian: A Painter of Angels Became the Father of Camouflage by Richard Meryman, April 1999 (Article contrasting Thayer and Cott)