Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite.
Nocturnal creatures generally have highly developed senses of hearing, smell, and specially adapted eyesight. Such traits can help animals such as the Helicoverpa zea moths avoid predators. Some animals, such as cats and ferrets, have eyes that can adapt to both lowlevel and bright day levels of illumination (see metaturnal). Others, such as bushbabies and (some) bats, can function only at night. Many nocturnal creatures including tarsiers and some owls have large eyes in comparison with their body size to compensate for the lower light levels at night. More specifically, they have been found to have a larger cornea relative to their eye size than diurnal creatures to increase their visual sensitivity: in the low-light conditions. Nocturnality helps wasps, such as Apoica flavissima, avoid hunting in intense sunlight.