Nocturnal features generally have highly developed senses of hearing and smell, and specially adapted eyesight. Some animals, such as cats and ferrets, have eyes that can adapt to both low-level and bright day levels of illumination. Others, such as bush babies and (some) bats, can function only at night. Many nocturnal creatures including tarsiers and some owls have large eyes in comparison to their body size in order to compensate for the lower light levels during the night