Night Moves

A raccoon sleeps in a pecan tree. Raccoons are primarily nocturnal. 

Let’s call it a night. For many, this means the day’s activities are done and it’s time for rest. Yet for many of Earth’s inhabitants, activity is just beginning. This quiz will test you on how much you know about nocturnal creatures. Answers are below.

1. Approximately what percent of mammals are nocturnal?

A. 50 percent

B. 60 percent

C. 70 percent

D. 80 percent

2. The ability to see in the dark is important. Many nocturnal animals have larger eyes and pupils to allow more light to get in. Also, their retinas are almost entirely composed of rod cells, which can capture even the tiniest bit of light. Their retinas contain fewer cone cells than animals that are active in the day. What do cone cells detect?

A. Depth perception

B. Movement

C. Color

D. Clarity

3. Many nocturnal have a tapetum lucidum in their eyes. (Humans do not.) What does a tapetum lucidum do?

A. It is a tissue at the back of the eye that reflects light for better vision in low-light situations.

B. It causes the eyes of some animals, such as cats, glow in the dark.

C. It is a tissue at the back of the eye that allows animals to collect ultraviolet light in the dark.

D. A & B

4. A heightened sense of smell is also present in most nocturnal animals. Many amphibians and reptiles, as well as some mammals (but not humans), have a Jacobson’s organ, which can detect scent on moist air. Where is this organ located?

A. In their nostrils

B. In the roof of their mouths

C. In a small pit in each cheek

D. In their ears

5. Many small birds, even those usually active during the day, will migrate at night. Why?

A. The air is less turbulent.

B. They use the stars to navigate.

C. They can use the same routes as birds of prey, which, as a rule, must migrate while the sun is out to take advantage of daytime thermal currents to soar.

D. All of the above.

6. Many birds sing at night. Which of these is not a reason?

A. To mark their territory

B. To make it difficult for nearby predators to sleep

C. To attract mates

D. There is less background noise, so their song carries farther.

7. Nocturnal fish, in general, have behaviors and physical features that differ from those of diurnal fish. Which of these is not true?

A. They are more likely to be solitary and carnivorous.

B. They tend to not swim as fast as diurnal fish.

C. They tend to have smaller eyes.

D. They are more likely to be yellowish brown or red. As light levels drop at night, these are the first colors on the spectrum to become imperceptible.

8. As far as scientists can tell, plants do not sleep. Even so, they are creations of habit, and many of their life processes can be tied to either day or night. During the day, they use the sun’s energy to turn water, minerals and carbon dioxide into sugars (food) during a chemical process called photosynthesis. What do they do at night?

A. The sugars move to different parts of the tree, where they are “consumed.”

B. Their roots release excess sugar and water into the soil.

C. They use moonlight to store this energy into food reserves for the winter.

D. They turn this energy into a pesticide.


1. C; 2. C; 3. D; 4. B; 5. D; 6. B; 7. C; 8. A

Kathleen Gaskell is the Bay Journal's copy and layout editor and author of the Chesapeake Challenge. Contact Kathleen at

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