Cats' pupils and extensor muscles have very strong contractility, which can be reduced or enlarged with the intensity of light. During the day, under the strong sunlight, its pupil can contract like a line; In the darkness of night, the pupils are wide open like a full moon; In the light of moderate intensity in the morning or evening, the pupil will become the shape of jujube stone.
Cats' eyes are like lines, and they can still see clearly. Because its pupil has greater contractility than human pupil and is more sensitive to light, even if the light is too strong or too weak, it will not affect vision and can still see things clearly.
Extended data:
The different colors of kittens' pupils are actually related to the color display around kittens' pupils. That part is called the iris. The reason why iris can produce color is related to melanocytes. The main function of melanocytes is to form melanin, and the amount of melanin is actually the decisive factor to determine the color of kitten pupils.
If the number of melanocytes is small and the activity is low, then the melanin produced is naturally less, and the color is closer to green and lighter; On the other hand, if the number of melanocytes is large, more melanin is produced, so the color is closer to orange-red and darker.