Hall Rebecca Jehne, Robson Simon K A, Ariel Ellen
College of Science and Engineering: Zoology and Ecology, James Cook University, Townsville, Queensland, Australia.
College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia.
PeerJ. 2018 Sep 19;6:e5572. doi: 10.7717/peerj.5572. eCollection 2018.
Several anatomical studies provide evidence that green turtles ( possess the necessary anatomy for colour vision. Behavioural experiments have previously been conducted with newly emerged hatchlings, concluding that they are attracted to shorter wavelengths compared to longer wavelengths within a terrestrial environment, suggesting a possible attraction towards blue. This paper assessed the colour vision of hatchlings within an aquatic environment, and investigated whether the attraction for shorter wavelengths remains consistent within water, whether the colour saturation of the chromatic stimuli was an important factor, and whether rearing and testing individual animals in different coloured housing tanks has an impact on their visual choices.
Forty-one hatchling green turtles were presented with a three-choice experiment where food was attached to three different coloured plates. The plates (blue, yellow, and red) were randomly arranged in the turtle's tank and four different colour saturations were tested (100, 75, 50, and 25%). Turtles were individually placed into their housing tanks (coloured either red, white, blue or grey) with three different colour plates in front of them, from the same saturation level. The colour of the plate with food first approached and bitten by the turtle was recorded.
The colour of the tank in which an individual was reared, and where experiments were conducted, significantly influenced which food item was selected on the different coloured plates. While individual turtles preferred to select the food items associated with blue plates across the entire experiment (66.1% of the time compared to 18.2% and 15.7% for yellow and red plates respectively), the preference for blue plates was influenced by the colour of the rearing/experimental tank. Individuals raised in red, white or blue tanks appeared to consistently prefer food on blue plates, but there appeared to be no plate colour preference by turtles in grey tanks. There was no significant effect of either colour saturation or the spatial arrangement of the three colours within an experimental tank on colour choice, and no significant interaction between tank colour and colour saturation.
Thesefindings confirm that the terrestrial preference towards shorter wavelength colours, such as blue, compared to longer wavelength colours remains consistent within an aquatic environment. This preference for blue continues even as the colour saturation reduces from 100% down to 25%, and the colours become darker. Thus, it is suggested that green turtle hatchlings have a strong attraction towards blue. This attraction, however, is influenced by the colour of the tank the turtles were raised in. While this supports the notion that environmental colour may influence individual turtle visual capabilities, it suggests that this relationship is more complicated, and requires further investigation.
多项解剖学研究表明绿海龟具备色觉所需的解剖结构。此前曾对新孵化出的幼龟进行行为实验，结果表明在陆地环境中，相较于较长波长，它们更倾向于较短波长，这表明它们可能对蓝色有偏好。本文评估了幼龟在水生环境中的色觉，并研究了在水中对较短波长的偏好是否保持一致，色刺激的颜色饱和度是否是一个重要因素，以及在不同颜色的饲养箱中饲养和测试个体动物是否会影响它们的视觉选择。
对41只绿海龟幼龟进行了一项三选一实验，将食物附着在三个不同颜色的盘子上。盘子（蓝色、黄色和红色）在海龟的水箱中随机排列，并测试了四种不同的颜色饱和度（100%、75%、50%和25%）。将海龟分别放入它们的饲养箱（颜色为红色、白色、蓝色或灰色）中，面前有三个来自相同饱和度水平的不同颜色的盘子。记录海龟首次接近并咬住的带有食物的盘子的颜色。
饲养个体以及进行实验的水箱颜色，对在不同颜色盘子上选择哪种食物有显著影响。虽然在整个实验过程中，个体海龟更倾向于选择与蓝色盘子相关的食物（66.1%的时间，而黄色和红色盘子分别为18.2%和15.7%），但对蓝色盘子的偏好受饲养/实验水箱颜色的影响。在红色、白色或蓝色水箱中饲养的个体似乎一直更喜欢蓝色盘子上的食物，但灰色水箱中的海龟似乎没有盘子颜色偏好。实验水箱内颜色饱和度或三种颜色的空间排列对颜色选择均无显著影响，水箱颜色和颜色饱和度之间也无显著交互作用。
这些发现证实，与较长波长颜色相比，绿海龟在陆地环境中对较短波长颜色（如蓝色）的偏好在水生环境中保持一致。即使颜色饱和度从100%降至25%且颜色变深，对蓝色的这种偏好仍持续存在。因此，表明绿海龟幼龟对蓝色有强烈的吸引力。然而，这种吸引力受海龟饲养水箱颜色的影响。虽然这支持了环境颜色可能影响个体海龟视觉能力的观点，但表明这种关系更为复杂，需要进一步研究。
