Why do some animals see better at night?

Answer: More rod cells for dim light

Pupils that stay fully open all night — Wrong. Wide pupils help, but the critical factor is abundant rod photoreceptors that function in low light conditions.

More rod cells for dim light ✓ — Correct! Nocturnal animals have retinas dominated by rod cells (vs cones). Rods are extremely light-sensitive but don't detect color. Many also have tapetum lucidum—reflective layer giving photons a second chance to be detected. Trade-off: excellent night vision but poor daytime vision and color perception. Owls, cats are examples!

Eyes that produce their own faint glow — Wrong. Animals don't emit light for night vision. They have adaptations (rod cells, tapetum lucidum) to detect minimal available light efficiently.