Animal vision and colour change for camouflage

理解为什么同一物种的个体在种群之间和种群内部存在差异，包括在不同环境中发现的个体，以及导致这种差异的机制是生物学的基本问题。个体差异的一个主要原因是颜色的变化。这种能力在自然界广泛存在，从昆虫和甲壳类动物到爬行动物、鱼类和两栖动物。它发生的时间范围很广（秒、小时、天、周、月），通常涉及体内含有特殊色素的细胞的变化。颜色变化对许多物种的伪装至关重要，并且在头足类和变色龙等异常快速变化的物种中受到了广泛关注。然而，我们的知识中存在一个主要的空白——尽管人们普遍认为颜色变化是基于动物视觉检查背景，但很少有人对此进行直接调查。事实上，我们对变色动物的视觉系统是如何使它们适应视觉环境的知之甚少。该项目将研究两种常见的英国物种，它们在外观上高度多样化，并且已知能够改变颜色来伪装：岸蟹（Carcinus maenas）和变色龙对虾（Hippolyte varians）。它将包括在海洋水箱中对螃蟹和对虾进行实验，并将它们放在不同的背景下，以评估它们改变颜色的能力。利用特殊的图像分析技术和捕食者视觉模型，将评估每种背景颜色变化在提供伪装方面的有效性。同时，确定每个物种视觉中存在的光感受器以及它们可以探测到的光的波长的先进技术将用于表征每个物种的视觉能力。利用这些信息，可以构建对虾和螃蟹的视觉模型，并用于确定它们的视觉能力是如何引导和限制颜色变化的。最后，实验将使用彩色滤光片和LED灯来改变实验中的光照条件和模式，以梳理出飞行强度、方向和组成在指导颜色变化中的作用，以及其他因素（如饮食）。这个项目将是第一个结合对动物视觉能力和感知的先进理解，以及这如何允许和限制它们在广泛的视觉环境中改变颜色以隐藏的项目。

Understanding why individuals of the same species differ among and within populations, includingthose found in different environments, and the mechanisms that lead to such variation is afundamental problem in biology. A major cause of individual variation is colour change. This ability iswidespread in nature, from insects and crustaceans, through to reptiles, fish, and amphibians. Itoccurs on a wide range of timescales (seconds, hours, days, weeks, and months), and usually involveschanges in special pigment-containing cells in the body. Colour change is vital in guiding thecamouflage of many species, and has received much attention in unusually rapid changing speciessuch as cephalopods and chameleons. However, a major gap in our knowledge exists - although colourchange is widely assumed to be based on animals visually inspecting the background, this has rarelybeen directly investigated. In fact, we know very little about how the visual systems of colour changinganimals enable them to match their visual environment.This project will study two common UK species that are highly diverse in appearance and known to beable to change colour for camouflage: shore crabs (Carcinus maenas) and chameleon prawns(Hippolyte varians). It will involve conducting experiments in marine tanks with crabs and prawns andputting them on different backgrounds to assess their ability to change colour. Using special imageanalysis techniques and models of predator vision, the effectiveness of colour change on eachbackground in providing camouflage will be assessed. Concurrently, advanced techniques todetermine what photoreceptors are present in each species vision, and the wavelengths of light theycan detect, will be used to characterise the visual ability of each species. Using this information,models of prawn and crab vision can be constructed and used to determine how their visual abilityguides and constrains colour change. Finally, experiments will be conducted using coloured light filtersand LED lights to change the light conditions and patterns in experiments to tease apart the role oflight intensity, direction, and composition in guiding colour change, versus other factors, such as diet.This project will be the first to combine advanced understanding of the visual abilities and perceptionof animals and how this allows and constrains them to change colour for concealment in a wide rangeof visual environments.