Bottlenose dolphins breathe air but can sleep in the ocean because
A) they cease breathing while sleeping and remain underwater.
B) they sleep for only 30 minutes at a time, which is the maximum interval they can cease breathing.
C) they fill their swim bladder with air to keep their blowholes above the surface of the water while they sleep.
D) they move to shallow water to sleep, so they do not need to swim to keep their blowholes above the surface of the water.
E) they alternate which half of their brains is asleep and which half is awake.

Question

Quizplus · Accepted Answer

Bottlenose dolphins have the ability to alternate which half of their brain is asleep and which half is awake. This is known as unihemispheric sleep, and it allows the dolphin to rest while still being alert enough to surface and breathe as necessary. This also allows them to sleep while still remaining attentive to potential predators or other threats in their environment.

Bottlenose Dolphins Breathe Air but Can Sleep in the Ocean