Did you ever wonder what goes on in an animal’s brain or body while it is sleeping? Take this quiz to learn about a few animals’ sleeping habits. Answers are below.

1. Dolphins swim while they sleep. How do they manage this?
A. Dolphins sleep in shifts, and those that are awake poke the sleeping ones if they start to sink.
B. Dolphins only sleep for a minute at a time, which is not enough time for a dolphin to drown.
C. Dolphins can turn off half their brain, and the other half lets it know when it is time to come up for air. Not only that, but they keep one eye open to keep a lookout for predators.
D. Dolphins don’t sleep.

2. Why do brown bats — which can sleep 12–19 hours at a time — sleep upside down from the ceiling?
A. It causes blood to flow to the brain, which keeps the bat alert to danger, even while sleeping. Plus, the bat’s muscles are most relaxed in this position.
B. They are less likely to be spotted by prey there.
C. It’s easier for a bat to take off flying from this position. In fact, their wings aren’t strong enough to take off from the ground.
D. B & C

3. If you are a mammal, are you more likely to sleep once a day or several times a day?

4. Some animals sleep out in the open; others hide when sleeping. Which type of animal is more likely to sleep out in the open, a predator species or a prey species?

5. Why do some birds sleep with their bills (which contain their nose openings, called nares) tucked under their shoulders or backs?
A. It warms the air that the bird breathes, should temperatures get cold at night.
B. It deadens the sound of a bird’s whistling or snoring in its sleep, making the bird’s location less obvious to predators.
C. The position stretches out the bird’s neck muscles, which tighten up when the animal is awake.
D. The bird’s breath forces out any parasites that might have burrowed under its feathers.

6. Why do wading birds like herons and egrets stand in water while they sleep?
A. The water cools off their feet, which reduces their body temperature and helps the birds to sleep better.
B. They can sense approaching predators through sounds and vibrations in the water.
C. The sounds and vibrations in the water lull them to sleep.
D. They might fall out of a tree during a deep sleep.

7. Smaller birds (whose feet can clamp around a branch so they don’t fall out of the tree while sleeping) tend to perch close to the tree trunk, high up in a tree when they sleep. Why?
A. The trunk provides better shelter than an outer branch.
B. The trunk may still hold warmth from the day’s sun.
C. Predators climbing the tree will cause vibrations and noise, alerting the bird in time to escape.
D. All of the above.

8. Why do fish sleep with their eyes open?
A. Unless they are a shark, they don’t have eyelids.
B. Their eyelids are transparent, so it only looks like they are not sleeping.
C. They don’t want to miss out on any nearby action.
D. Their eyes help them blend in better with their surroundings.



1. C; 2. D; 3. Several times a day; 4. Predator; 5. A; 6. B; 7. D; 8. A