Well, for animals that are trying to avoid predators by staying in the darkness, light can still be very useful for the three basic things that animals have to do to survive: and that's find food, attract a mate and avoid being eaten.
为了躲避捕食者， 他们躲在黑暗里。 然而为了生物体的存活， 光的重要性至少能体现在最基本的三件事上 那就是寻找食物， 吸引异性，以及躲避天敌。