Ducks Sleep With One Eye Open
Many duck species rest on the water with one eye open and one half of their brain awake. This clever adaptation helps them stay alert to predators while still getting needed rest. Scientists call this behavior unihemispheric slow-wave sleep.
💡 Fun detail:
The eye facing outward stays open and watchful, while the other eye closes, letting ducks guard their flock without losing precious rest time.
Source: National Geographic