猫的眼睛，为什么竖着一条缝？

Cat pupils are like thin vertical slits. 猫的瞳孔，是竖着的一条细缝。 In bright light, the slit gets tiny. 强光下，细缝缩成一条线。 In the dark, it opens wide like a circle. 黑夜里，它又张得圆圆的。 This helps the cat judge distance and light. 这样，猫能算准距离和亮度。 It is perfect for catching mice at night. 夜里抓老鼠，正好用得上。 Round-eyed hunters see the world differently. 圆瞳孔的动物，看世界就是另一个样。