You may think it's normal to be awake during the day and sleep at night, but that's not true for all animals. Humans are diurnal, the
scientific term for tending to be up and about during the hours when
the sun is up. Being awake in daytime has some obvious advantages:
It's warm, it's easy to see, and, at least for humans, sunshine provides
much-needed vitamin D and also makes us feel good.
But for many animals, being up at night, or being nocturnal, is a great
arrangement. Small animals who are in danger from predators can
gather food more safely in the dark. And some animals can find their
way around by using senses other than sight - bats, for example, use
their sense of hearing to navigate. In hot climates, it can also be a
good thing to avoid the bright sun and spend the day curled up in a
cozy cave or den.
Which statement best summarizes two central ideas of the text?