A domestic cat’s eye narrows to a razor-thin vertical slit in bright sunlight, while a grazing sheep stares out through a wide horizontal bar. These are not cosmetic quirks. A 2015 study in Science ...

It's easy to think of pupils as simple holes that widen in the dark and shrink in the light. But if you look across the animal kingdom, you'll see a variety of pupil shapes: vertical slits in cats and ...

Each animal in nature has undergone thousands of years of evolution to reach its current form. This has resulted in some ...