Data from: Changeable camouflage: how well can flounder resemble the colour and spatial scale of substrates in their natural habitats?

Flounder change colour and pattern for camouflage. We used a spectrometer to measure reflectance spectra, and a digital camera to capture body patterns of two flounder species camouflaged on four natural backgrounds of different spatial scale (sand, small gravel, large gravel, rocks). We quantified the degree of spectral match between flounder and background relative to the situation of perfect camouflage in which flounder and background were assumed to have identical spectral distribution. Computations were carried out for three biologically relevant observers: monochromatic squid, dichromatic crab, and trichromatic guitarfish. Our computations present a new approach to analyzing datasets with multiple spectra that have large variance. Furthermore, to investigate the spatial match between flounder and background, images of flounder patterns were analyzed using a custom program originally developed to study cuttlefish camouflage. Our results show that all flounder and background spectra fall within the same colour gamut and that, in terms of different observer visual systems, flounder matched most substrates in luminance and colour contrast. Flounder matched the spatial scales of all substrates except for rocks. We discuss findings in terms of flounder biology; furthermore, we discuss our methodology in light of hyperspectral technologies that combine high-resolution spectral and spatial imaging.比目鱼会通过改变体色与体表纹路实现伪装。本研究使用分光光度计（spectrometer）测量反射光谱，并使用数码相机拍摄两种比目鱼在四种不同空间尺度的自然背景（沙粒、小砾石、大砾石、岩石）上伪装时的体表纹路。我们以完美伪装场景——即假设比目鱼与背景的光谱分布完全一致——为参照，量化了比目鱼与背景之间的光谱匹配程度。本研究针对三种具有生物学相关性的视觉系统开展计算：单色视觉的鱿鱼、二色视觉的蟹类以及三色视觉的犁头鳐。本研究的计算方法为分析存在较大方差的多光谱数据集提供了全新路径。此外，为探究比目鱼与背景的空间匹配度，研究团队使用一款最初用于研究乌贼伪装的定制程序，对比目鱼纹路图像开展分析。研究结果显示，所有比目鱼与背景的光谱均处于同一色域（colour gamut）范围内；且针对不同视觉系统的观察者而言，比目鱼在多数基底的亮度与色彩对比度上均实现了匹配。除岩石基底外，比目鱼均能匹配其余所有基底的空间尺度。本研究结合比目鱼生物学特性对研究结果展开讨论；此外，还结合融合高分辨率光谱与空间成像的高光谱技术（hyperspectral technologies）对本研究的方法学进行了阐述。