Question: Why can some animals only see black and white?

Prateek Buch answered on 15 Jun 2011:

excellent question! many animals that are active at night, or around dawn and dusk, have to wander around in really dim light. Their eyes have lots of rod cells which are sensitive to low-levels of light, but these cells aren’t able to sense colour. We also have rod cells in our retina, and we use them when it’s really dark. But we have cone cells too, which can sense different colours – animals that can only see black and white either don’t have cones or they aren’t active at low levels of light, so they can only see black and white!