Nocturnal animals are active during the night and sleep during the day
Nocturnal animals generally have highly developed senses of hearing, smell, and specially adapted eyesight. This helps them to avoid predators. Some animals, such as cats and ferrets, have eyes that can adapt to both lowlevel and bright day levels of light. Others, such as bushbabies and (some) bats, can function only at night. Many nocturnal creatures including some owls have large eyes in comparison to their body size to compensate for the lower light levels at night.
Source: Wikipedia
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