Martin Stevens | |
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Born | 1982 (age 40–41) [1] |
Education | Bristol University (BSc, PhD) |
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Institutions | University of Exeter University of Cambridge |
Martin Stevens is a British sensory and evolutionary ecologist, an underwater photographer and a natural history and popular science writer. He is known for his work on disruptive coloration in animal camouflage.
Stevens took his Ph.D. at the University of Bristol, in 2006. He then worked as a research fellow at the University of Cambridge, before moving to the University of Exeter, where his is a full Professor in its Centre for Ecology and Conservation. [2]
His research lies within the scope of sensory ecology, covering sensory systems, especially vision, and the evolutionary adaptations dealing with colour changing abilities. [3] Much of his work has been oriented to understand how colouration is used in nature, both defensively and opportunistically, in camouflage, mimicry and signalling. [4]
In 2017, Stevens and Dr Sarah Paul led a study commissioned by British Horseracing Authority in collaboration with the Royal Society for the Prevention of Cruelty to Animals. It resulted in the decision to change the colour in all Great Britain's jump course obstacles from orange to white. By the use of cutting edge camera equipment, the researchers successfully showed how the orange is perceived by horses as shades of green. This could be confusing, since the orange, used in the racecourse obstacles, could be blending with grass. The study hence concluded that the original orange should be substituted by either white, fluorescent yellow or light blue in order to improve animal welfare and safety. [5] [6] [7]
Stevens has published hundreds of journal papers, including Animal camouflage: current issues and new perspectives, [8] , Using digital photography to study animal coloration, [9] Disruptive coloration and background pattern matching. [10] In total, his articles have thousands of citations. [11]
Stevens is an award-winning underwater photographer. With an expressive part of his academic research being on coloration in animals, image analysis and camera technology had always been part of his work. But, since they were used for data collection purposes, they were more like "ID-style shots", as he puts it. As his studies on colours increasingly moved towards marine animals, Stevens, who had a longstanding hobby of wildlife photography, started to work with and develop the underwater techniques. Thus, he began to give more attention to the underwater lighting and scenery where he frames his objects, to create better image compositions, [12] "I’ve really worked on making my photographs aesthetically pleasing", he has mentioned. [13] He showcases his photo portfolios on the Sensory Ecology Instagram account and Wildlife Vision website.
In 2022, Stevens' Rock pool star, an over-under style shot of a spiny starfish in shallow waters, was the winner of the Underwater Photography of the Year competition, in the UK waters compact camera category. [14] His work has also been featured in a range of publications, including BBC Wildlife, BBC's Countryfile, Blue Marine Foundation, Marine Conservation Society [15] and Cornwall Wildlife Trust. [13]
He has commented that while he enjoys scuba diving, he takes most of his images while freediving or exploring tide pools and shallow inshore waters. [16] He has also noted that his frequent photographing spots are the beaches like Gyllyngvase, around Falmouth, Cornwall, where he is based, [13] with the further West locations of Helford estuary and Kynance Cove being among his preferred ones. A remarkable occasion that he recalls was snorkeling with blue sharks fifteen miles off the coast of Penzance. [12]
As usual in the area, he started with the more accessible GoPro. While progressing to more sophisticated compact cameras, he still used the action camera for wide-angle photo [17] and he has written a tutorial for underwater photography with a GoPro. [18] He eventually migrated to the more professional Olympus OM-D E-M5 Mark III. [16]
Besides the academic textbooks, Stevens has also written for a broader audience and has three books on popular science.
In Cheats and Deceits: How Animals and Plants Exploit and Mislead (2011), Stevens discusses how animals and plants use mimicry, deception, and trickery for protection, reproduction, and survival. With an experimental approach on the subject, he vindicates the works of the late-19th- and early-20th-century naturalists Abbott Thayer, Edward Poulton and Hugh Cott. [19] [20]
The 2021 release Life in Colour: How Animals See the World was published to accompany Sir David Attenborough's TV series Life in Colour and describes how vision is very particular for each kind of animal. The red-eyed tree frog from Costa Rica, for instance, has a peculiar ability. As Stevens describes, the frog has transparent eyelids, which allows it to look out for predators even when sleeping. [21]
In the same year, Stevens also released Secret Worlds: The Extraordinary Senses of Animals, an easy-reading version of his 2013 textbook, Sensory Ecology, Behaviour, and Evolution. Stevens investigates the high energy costs of having well-developed senses. An interesting fact described concerns the nocturnal ogre-faced spider, from Australia, which has such large and sensitive eyes that it must break down its photoreceptors and membranes during the day and then regenerate them to hunt at night. [22]
Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the battledress of a modern soldier, and the leaf-mimic katydid's wings. A third approach, motion dazzle, confuses the observer with a conspicuous pattern, making the object visible but momentarily harder to locate, as well as making general aiming easier. The majority of camouflage methods aim for crypsis, often through a general resemblance to the background, high contrast disruptive coloration, eliminating shadow, and countershading. In the open ocean, where there is no background, the principal methods of camouflage are transparency, silvering, and countershading, while the ability to produce light is among other things used for counter-illumination on the undersides of cephalopods such as squid. Some animals, such as chameleons and octopuses, are capable of actively changing their skin pattern and colours, whether for camouflage or for signalling. It is possible that some plants use camouflage to evade being eaten by herbivores.
Abbott Handerson Thayer was an American artist, naturalist, and teacher. As a painter of portraits, figures, animals, and landscapes, he enjoyed a certain prominence during his lifetime, and his paintings are represented in major American art collections. He is perhaps best known for his 'angel' paintings, some of which use his children as models.
In ecology, crypsis is the ability of an animal or a plant to avoid observation or detection by other animals. It may be a predation strategy or an antipredator adaptation. Methods include camouflage, nocturnality, subterranean lifestyle and mimicry. Crypsis can involve visual, olfactory or auditory concealment. When it is visual, the term cryptic coloration, effectively a synonym for animal camouflage, is sometimes used, but many different methods of camouflage are employed by animals or plants.
Hugh Bamford Cott was a British zoologist, an authority on both natural and military camouflage, and a scientific illustrator and photographer. Many of his field studies took place in Africa, where he was especially interested in the Nile crocodile, the evolution of pattern and colour in animals. During the Second World War, Cott worked as a camouflage expert for the British Army and helped to influence War Office policy on camouflage. His book Adaptive Coloration in Animals (1940), popular among serving soldiers, was the major textbook on camouflage in zoology of the twentieth century. After the war, he became a Fellow of Selwyn College, Cambridge. As a Fellow of the Zoological Society of London, he undertook expeditions to Africa and the Amazon to collect specimens, mainly reptiles and amphibians.
Countershading, or Thayer's law, is a method of camouflage in which an animal's coloration is darker on the top or upper side and lighter on the underside of the body. This pattern is found in many species of mammals, reptiles, birds, fish, and insects, both in predators and in prey.
Nature photography is a wide range of photography taken outdoors and devoted to displaying natural elements such as landscapes, wildlife, plants, and close-ups of natural scenes and textures. Nature photography tends to put a stronger emphasis on the aesthetic value of the photo than other photography genres, such as photojournalism and documentary photography.
Animal colouration is the general appearance of an animal resulting from the reflection or emission of light from its surfaces. Some animals are brightly coloured, while others are hard to see. In some species, such as the peafowl, the male has strong patterns, conspicuous colours and is iridescent, while the female is far less visible.
A camera trap is a camera that is automatically triggered by motion in its vicinity, like the presence of an animal or a human being. It is typically equipped with a motion sensor – usually a passive infrared (PIR) sensor or an active infrared (AIR) sensor using an infrared light beam.
Fur is a thick growth of hair that covers the skin of almost all mammals. It consists of a combination of the oily outer guard hairs and thick underfur beneath. The guard hair keeps moisture from reaching the skin; the underfur acts as an insulating blanket that keeps the animal warm.
Underwater camouflage is the set of methods of achieving crypsis—avoidance of observation—that allows otherwise visible aquatic organisms to remain unnoticed by other organisms such as predators or prey.
Disruptive coloration is a form of camouflage that works by breaking up the outlines of an animal, soldier or military vehicle with a strongly contrasting pattern. It is often combined with other methods of crypsis including background colour matching and countershading; special cases are coincident disruptive coloration and the disruptive eye mask seen in some fishes, amphibians, and reptiles. It appears paradoxical as a way of not being seen, since disruption of outlines depends on high contrast, so the patches of colour are themselves conspicuous.
Adaptive Coloration in Animals is a 500-page textbook about camouflage, warning coloration and mimicry by the Cambridge zoologist Hugh Cott, first published during the Second World War in 1940; the book sold widely and made him famous.
Animal Coloration, or in full Animal Coloration: An Account of the Principal Facts and Theories Relating to the Colours and Markings of Animals, is a book by the English zoologist Frank Evers Beddard, published by Swan Sonnenschein in 1892. It formed part of the ongoing debate amongst zoologists about the relevance of Charles Darwin's theory of natural selection to the observed appearance, structure, and behaviour of animals, and vice versa.
Deception in animals is the transmission of misinformation by one animal to another, of the same or different species, in a way that propagates beliefs that are not true.
Snow camouflage is the use of a coloration or pattern for effective camouflage in winter, often combined with a different summer camouflage. Summer patterns are typically disruptively patterned combinations of shades of browns and greys, up to black, while winter patterns are dominated by white to match snowy landscapes.
Animal coloration provided important early evidence for evolution by natural selection, at a time when little direct evidence was available. Three major functions of coloration were discovered in the second half of the 19th century, and subsequently used as evidence of selection: camouflage ; mimicry, both Batesian and Müllerian; and aposematism.
Coincident disruptive coloration or coincident disruptive patterns are patterns of disruptive coloration in animals that go beyond the usual camouflage function of breaking up the continuity of an animal's shape, to join up parts of the body that are separate. This is seen in extreme form in frogs such as Afrixalus fornasini where the camouflage pattern extends across the body, head, and all four limbs, making the animal look quite unlike a frog when at rest with the limbs tucked in.
Timothy M. Caro is a British evolutionary ecologist known for his work on conservation biology, animal behaviour, anti-predator defences in animals, and the function of zebra stripes. He is the author of several textbooks on these subjects.
Peter John Herring is an English marine biologist known for his work on the coloration, camouflage and bioluminescence of animals in the deep sea, and for the textbook The Biology of the Deep Ocean.