Question

The retina of nocturnal birds contain:

• A. Only cones
• B. Only rods
• C. Both (a) and (b)
• D. None of the above

Answer 1

The correct option is B Only rods

The retina of nocturnal birds, such as owls, contains only rods. The rods are longer, slender and cylindrical, while cones are shorter, thicker and somewhat cube-shaped. Rods are related with vision in dim light, whereas, cones are related to day vision and colour vision. Since nocturnal animals are more exposed to darkness than light, they will have only rods.