Animals that sleep with one eye open. This behaviour is a way for them to stay safe and alert while they are resting. Here are some animals that sleep with one eye open:
Dolphins and whales
These marine mammals use a sleep state called unihemispheric sleep, where one half of their brain is asleep while the other half is awake. This allows them to keep watch for predators and to surface for air while they are sleeping.
Penguins
Penguins often sleep standing up, with one eye open to keep an eye out for predators. They may also sleep while floating on their backs in the water, with one eye open to watch for food.
Blackbirds
These birds are often found sleeping in groups, with one bird perching on top of another. The bird on top will typically keep an eye open to watch for predators.
Peregrine falcons
These birds of prey are known for their speed and agility. They often sleep while perched on high perches, with one eye open to watch for prey.
Fruit bats
These bats are nocturnal, and they often sleep during the day. They may sleep in groups, with one bat perching on top of another. The bat on top will typically keep an eye open to watch for predators.
Crocodiles
These reptiles are often found sleeping in the water. They may sleep with their eyes open, or they may close their eyes and keep their nostrils open to breathe.