The giant freshwater prawn Macrobrachium rosenbergii larvae have apposition eyes and are positively phototactic, whereas the postlarvae (PL) have superposition eyes and are negatively phototactic. M. rosenbergii has colour vision as early as larval stage. We discovered that M. rosenbergii alters background colour preference after metamorphosis from larvae to PL in association with nature of phototaxis. The test circular glass aquaria covered with a pair of two‐colour papers contained with a group of 100 larvae or 20 Pl, and the number of individuals in each colour background was recorded five times for each colour pair. The background colours tested were light blue, green, yellow, red, white and black. The numbers of larvae or PL in each colour background of different pairs were analysed by the Thurstone's law of comparative judgment. In the larvae, significant bias towards yellow was evident. In the PL, of the four pairings of black with other colours, all biased to black. The mean z‐scores were highest for yellow in the larvae, and for black in the PL. To determine the possible background brightness preference of the larvae and PL, six different colour backgrounds were presented in pairs. The larvae significantly preferred light blue over dark blue, white over yellow and white over black. The PL exhibited reversed preference. The relationship between z‐scores and light reflectance levels of five colour papers was significantly positive in the larvae and negative in the PL. The observed background colour preference was probably due to relative brightness rather than chromaticity difference.

中文翻译：

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大型淡水虾罗氏沼虾在从幼虫到幼虫的变态后改变背景颜色的偏好：与趋光性相关

巨型淡水虾罗氏沼虾幼虫具有并列眼，并且具有正向趋光性，而后幼虫（PL）具有重叠眼，并且具有负趋光性。罗氏沼虾早在幼虫期就有色觉。我们发现罗氏沼虾改变从幼虫到PL变态后与趋光性相关的背景颜色偏好。测试圆形玻璃水族箱覆盖有一对双色纸，其中包含一组100只幼虫或20个Pl，并且每个颜色对记录了每个颜色对五次，每个颜色对。测试的背景色为浅蓝色，绿色，黄色，红色，白色和黑色。根据瑟斯通的比较判断定律，分析不同对的每种颜色背景中的幼虫或PL的数量。在幼虫中，明显偏黄。在PL中，黑色与其他颜色的四对配对中，全部偏向黑色。均值z幼虫中黄色得分最高，PL中黑色得分最高。为了确定幼虫和PL可能的背景亮度偏爱，成对呈现了六个不同的颜色背景。幼虫明显偏爱浅蓝色而不是深蓝色，白色偏爱黄色，白色偏爱黑色。PL表现出相反的偏好。五种彩色纸的z得分与光反射率之间的关系在幼虫中显着为正，而在PL中为负。观察到的背景颜色偏爱可能是由于相对亮度而不是色度差异。