Nocturnal animals are said to sacrifice colour vision in favour of increased absolute sensitivity. This is true for most vertebrates that possess a dual retina with a single type of rod for colour-blind night vision and multiple types of cone for diurnal colour vision. However, among the nocturnal vertebrates, geckos are unusual because they have no rods but three cone types. Here, we show that geckos use their cones for colour vision in dim light. Two specimens of the nocturnal helmet gecko Tarentola (formerly Geckonia) chazaliae were able to discriminate blue from grey patterns by colour alone. Experiments were performed at 0.002 cd m(-2), a light intensity similar to dim moonlight. We conclude that nocturnal geckos can use cone-based colour vision at very dim light levels when humans rely on colour-blind rod vision.
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机译：据说夜间动物为了增强绝对敏感性而牺牲了色觉。对于拥有双视网膜，带有用于视力盲视的单一类型杆和用于日间色觉的多种视锥的大多数脊椎动物而言，这是正确的。但是，在夜间脊椎动物中，壁虎是不寻常的，因为它们没有杆，只有三种圆锥体。在这里，我们展示了壁虎将它们的视锥细胞用于昏暗光线下的彩色视觉。夜间头盔壁虎塔伦托拉（前壁虎）chazaliae的两个标本能够通过单独的颜色区分蓝色和灰色图案。实验在0.002 cd m（-2）的光强度下进行，类似于昏暗的月光。我们得出的结论是，当人类依赖色盲视杆视觉时，夜间壁虎可以在非常暗的光线水平下使用基于圆锥体的色彩视觉。
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