Research overview: why big cats have round pupils and small cats have slits

Although domestic cats have vertical-slit pupils, large felids such as lions and tigers have round pupils, a contrast that has attracted scientific attention. This overview surveys the explanation tied to ambush ecology and body height: the depth-of-field and distance-judging advantages of a slit pupil are strongest for short predators whose eyes sit close to the ground, while taller predators gain less from them. As felid body size increases, the slit advantage diminishes and round pupils become more common. The survey relates this pattern to the broader correlation between pupil shape and lifestyle found across animals. It explains why two closely related cats, a house cat and a lion, can have such different pupils despite similar predatory habits. The size-dependent shift in pupil shape within the cat family is a compelling illustration of how eye height and ecology jointly shape visual anatomy.