Which statement describes the typical retina composition of a nocturnal mammal as given?

• A. More cones and lower concentration of rods
• B. Equal numbers of cones and rods
• C. Fewer cones and greater concentration of rods
• D. No cones present

Answer: (C)

In dim light, vision relies on rods, which are highly sensitive to low light but don’t detect color or fine detail like cones do. Nocturnal mammals adapt by having retinas with many more rods than cones, so there are fewer cones overall and a greater concentration of rods. This arrangement boosts light sensitivity, helping them see better at night, though color vision and sharpness are reduced. Some nocturnal species also have a tapetum lucidum that reflects light back through the retina to gain extra sensitivity, but the key idea is the rod-dominated retina. That’s why the statement describing fewer cones and a greater concentration of rods is the correct description.