动物们如何进行伪装

Camouflage is the by-product of an evolutionary arms race between one group - the predators - that want to eat another group - the prey.

伪装是想要吃掉猎物的捕食者群体和猎物群体之间进化竞赛的副产品。

Prey seek to survive by tricking the perceptual and cognitive systems of the predators.

猎物通过欺骗捕食者的感知和认知系统得以生存。

And predators look to eat by breaking through the camouflage of the prey.

捕食者通过识破猎物的伪装来寻找食物。




To put it all more formally, predators need to maximise their perception of signal (their proposed meal) from the noise (the general environment); the goal of prey is to minimise that same signal-to-noise ratio.

更专业一点来说,捕食者需要将自己感知“信号”(他们可能的食物)的能力在噪音中(一般环境中)最大化;而猎物的目标是将相同的信噪比降至最低。

While the physical manifestations of camouflage might be diverse, they function in one of three ways: to impair detection, to impair identification or to redirect attack.

虽然伪装的物理表现可能多种多样,但它们的作用方式一般有三种:干扰捕食者的探测、干扰捕食者的识别,以及改变其攻击方向。

Methods that impair detection trick the perceptual system of a predator into believing that the prey is simply not there.

干扰捕食者的探测指欺骗捕食者的感知系统,让他们相信猎物根本不在那里。

Octopuses change colour to match their backgrounds, for example.

举例来说,章鱼会改变自己身体的颜色,使之与背景融为一体。

The tasselled wobbegong shark conceals its shadow against the ocean floor by being incredibly wide and flat.

叶须鲨的体型十分宽大而平坦,能够将自己隐藏在海底。

The white bellies of penguins match the sky, and their black coats, the depths of the ocean, in what is known as "countershading".

企鹅腹部的白色与天空的颜色相一致,背部的黑色皮毛与海洋深处的颜色相一致,这也就是我们所说的“反荫蔽”。

The arctic fox sports white fur in the winter and brown or grey in the summer.

北极狐的皮毛在冬天是白色,在夏天是棕色或灰色。

The comb jelly is transparent.

栉水母身体是透明的。

Deep-sea fish are very black.

深海鱼的颜色很黑。

Often, the evolution of this kind of camouflage is detectable on a shorter timescale too - the populations of dark-coloured peppered moths grew in England, for example, as sooty pollution increased in the 19th century during the Industrial Revolution.

通常来说,在较短一段时间内也能观察到伪装的进化发展——例如,19世纪工业革命期间,烟尘污染增加时,英国深色胡椒蛾的数量有所增加。

Correspondingly, the population of light-coloured moths rose when pollution levels fell.

相应地,当污染水平下降时,浅色蛾的数量会有所增加。

Impairing identification tricks the cognitive system of predators into thinking that whatever it is looking at is uninteresting (and definitely not food-like).

干扰捕食者的识别指引导捕食者的认知系统,使其认为自己目前正在观察的东西毫无趣味(而且肯定不像食物)。

The dead leaf butterfly, for example, looks like a dead leaf.

例如,枯叶蛱蝶看起来就像一片枯叶。

Predators themselves use this too - leopards have high-contrast disruptive patterning which allows them to better blend into shadowy bushes and tall grass to avoid detection by their prey.

捕食者自己也使用这种技巧——豹子身上有高对比度的破坏性花纹,这使得它们能够更好地融入幽暗的灌木丛和高高的草丛中,以免被猎物发现。

Redirecting attention is a way to try to reduce the lethality of attack, thereby increasing the chances of survival.

转移注意力是试图降低捕食者攻击强度,从而增加自身生存机会的技巧。

The eyespots on the wings of a peacock butterfly, for example, divert attention towards less important regions of the insect's body.

例如,孔雀蛱蝶翅膀上的眼点会让捕食者的注意力转移到它身体不太重要的区域。

Zebras' stripes deploy a technique called "motion dazzle", which disrupts a predator's ability to work out which direction the animals are moving in.

斑马的条纹利用了一种名为“运动性眩晕”的错觉,可以扰乱捕食者对其移动方向的判断。

How good are any of these camouflage tactics?

这些伪装战术有多有效?

A study published this week in Proceedings of the Royal Society B tries to find out.

本周发表在《英国皇家学会会刊B》上的一项研究试图找出答案。


Joao Vitor de Alcantara Viana and colleagues from the State University of Campinas, in Brazil, compiled results from 84 studies on camouflage.

巴西坎皮纳斯州立大学的若昂·维托尔·德·阿尔坎塔拉·维亚纳和他的同事汇总了84项关于猎物伪装的研究结果。

They found that camouflage increased the amount of time a predator spent searching by over 60%, and it decreased the number of prey that were detected and attacked by around 25%.

他们发现,猎物的伪装导致捕食者寻找食物的时间增加了超过60%,被发现并受到攻击的猎物数量减少了约25%。

Masquerade (the dead leaf butterfly, for example) was the most effective technique, nearly quadrupling the time predators spent searching.

假扮(例如枯叶蛱蝶)是最有效的战术,能够让捕食者寻找猎物时间变为原来的四倍。

Eyespots on butterfly wings seemingly provided no benefits in terms of hiding time from predators, but Mr. Alcantara noted that this was not surprising since that tactic is not meant to interfere with detection, but rather to reduce the lethality of an attack.

蝴蝶翅膀上的眼点在躲避捕食者方面似乎没有任何作用,但阿尔坎塔拉先生指出,这是很正常的,因为眼点并不是为了干扰捕食者探测,而是为了降低其攻击的杀伤力。

Camouflage need not be visual.

伪装不一定是视觉上的伪装。

Bats, for example, perceive the world through sound.

例如,蝙蝠通过声音感知世界。

Some of the moths they predate have therefore evolved a "stealth coat" - made of tiny hairs and a layer of scales - that reduces their detectability through echolocation.

因此,它们捕食的一些蛾子进化出了一种“隐形皮毛”——由微小的毛发和一层鳞片组成——降低了它们在蝙蝠的回声定位中被探测到的可能性。

Marc Holderied, a biologist at the University of Bristol, wanted to know how good the moths were at hiding from bats so he shaved off their hairs and then sent sound waves towards them, mimicking how bats might echolocate to find their prey.

布里斯托尔大学的生物学家马克·霍尔德里德想知道飞蛾躲避蝙蝠的能力有多强,所以他剃掉了飞蛾的毛,然后向它们发送声波,模仿蝙蝠寻找猎物时的回声定位。

The moths' one-and-a-half-millimetre layer of fur, it turned out, reduced their detectability by just over 40%.

事实证明,有一层半毫米毛皮的飞蛾被探测的可能性降低了超过40%。

In addition to the fur, moths also have a thin layer of scales, tens to hundreds of thousands of them, on each wing.

除了毛皮,飞蛾的每只翅膀上都有一层薄薄的鳞片,数量从数万到数十万片不等。

The scales each respond to specific frequencies of sound waves and when a bat's echolocation signals hits the moth's wings, the scales start to vibrate.

每片鳞片都会对特定频率的声波做出反应,当蝙蝠的回声定位信号击中飞蛾的翅膀时,鳞片开始振动。

The acoustic energy from the echolocation is thus absorbed.

这样,回声定位产生的声能就会被吸收。

Dr. Holderied and his colleagues tested how well the scales worked and found that they were just as good at absorbing sound as the fur - they absorbed as much as 87% of the incoming sound energy, but at only one tenth of the fur's thickness.

霍尔德里德博士和他的同事们测试了鳞片的工作情况,发现它们在吸收声波方面效果与毛皮一样好——它们能够吸收高达87%的传入声能,但其厚度只有毛皮的十分之一。

In terms of their ability to absorb sounds, Dr. Holderied says the moth's scales outperform (and are much thinner than) any human-designed soundproofing used in homes and offices.

霍尔德雷德博士表示,就吸收声波的能力而言,飞蛾的鳞片比任何家庭和办公室使用的人类设计的隔音材料都要好得多(也要薄得多)。

Camouflage not only provides a backdoor into glimpsing the magnificently diverse sensory worlds of animals, it has also inspired intriguing applications for people.

伪装不仅提供了一扇窗,让人们得以一窥动物多姿多彩的感官世界,还启发人们进行有趣的创作。

Artists and anti-technology activists have invented make-up techniques, for example, known as "computer vision dazzle" that take their cues from natural camouflage and work by drawing high-contrast contours and colourful shapes on human faces so that they can evade detection by computer facial recognition.

例如,艺术家和反科技活动人士发明了被称为“计算机视觉眩晕”的化妆技术,从自然界的伪装中获取灵感,在人脸上绘制高对比度的轮廓和五颜六色的花纹来逃避计算机的面部识别。

And Dr. Holderied's team has been taking inspiration from the miraculously sound-absorbing properties of moths to design wallpaper that can reduce the noise of road traffic for the occupants of a building.

霍尔德雷德博士的团队一直在从飞蛾神奇的吸音特性中获取灵感,设计能够为居民降低道路交通噪音的墙纸。

Though evolved in nature, camouflage can be useful in modern city life, too.

虽然伪装是自然界进化的产物,但也能用于现代城市生活。

来源:经济学人

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