Dog eyes have up to 3 eyelids: one upper eyelid, one lower eyelid and the third eyelid are located in the middle, slightly deep inside, helping to protect the eyes from dirt. Dogs distinguish objects first by movement, then light and finally shape. Because of this, their eyesight is very poor, dogs can see blue and yellow, but cannot distinguish between red and green. Specifically, the inside of a dog’s eye has two types of cones that can sense color, while in humans there are three. In return, they can be seen quite clearly in the dark.
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