The Zebra’s Stripes
CLASS COPY
Directions: On a new journal page, number 1-11 leaving space between the numbers. Record your responses
(or say “done” if there’s nothing to write) to the following tasks. You will need a textbook to complete this
activity.
1. Individually, read p.78 to form a context for the lesson. Then make a table in your journal like the one on p.79
comparing the different characteristics of the different zebras. Add an additional row to the table and label it
“ranges”.
2. Examine the pictures of the different zebras (on p. 78 and on the handouts). Discuss with your group how they
are similar and/or different. Record your observations in your table.
3. Examine the range map of Africa on the following page and add your observations to the table.
4. With your group, come up with a hypothesis answering the following question: Should the 4 zebras be
categorized into the same species, or in different species? Justify your answer with reasoning (“why”).
5. Read out loud with your group the sheet entitled, “Ideas about the Zebras Stripes”. Discuss each explanation
and record notes (evidence from text) together.
6. Brainstorm with your group the significance of stripes and how they are an adaptation (i.e., traits they’re born
with that help the organism survive and reproduce). Analyze together each piece of evidence (from “Ideas about
the Zebras Stripes”). List strong supporting evidence in your journal and highlight the strong supporting
evidence.
7. Give at least 3 key ideas that the additional reading gave you. That is, what was new to you?
8. With your group, review the characteristics chart on African Zebras. Record at least 3 characteristics from this
chart which support your original hypothesis. Label this list.
At this point, make sure your steps are numbered and show me your work to get your 1st of 3 stamps.
9. Which information from all 3 handouts did not support your original hypothesis? List information and label this.
10. Do you have enough information to support your hypothesis, or should you change your hypothesis based on
the new evidence? If so, create a new hypothesis and support it with evidence.
11. Explain whether you believe the four types of zebras should be considered the same or different species (can be
your original thought or a revised idea). Present 2 strong pieces of supporting evidence and place a box around
your response to this task.
At this point, make sure your last few steps are numbered and show me your work for the last stamp.
Ideas about the Zebra Stripes
Explanation 1: Zebra stripes act to camouflage the zebras from predators.
One explanation scientists commonly use for zebra stripes is that they somehow act to camouflage
the zebras from their predators, thus increasing the zebras' chances of survival. Zebras, like all
members of the horse family, are nomadic grazing animals (that is, they do not remain in one place
but rather roam across large territories). Their habitat ranges from open, grassy savannas to open
woodlands to arid brushlands. Although you might not expect bold and contrasting stripes to blend
into a background, some people have suggested that the stripes blend in well to a brushy background,
where there is a mixture of trees and bushes and a contrast between light and shadow. Other people
have suggested that the stripes camouflage the zebras especially well at dusk, a time when predators
might be more likely to attack. Several pieces of evidence, however, contradict this explanation. For
example, zebras are social animals that live in herds ranging in size from two to 20 individuals.
(The size of the herd depends on the species of zebra, the environmental conditions of climate, and
the availability of water and food.) In these herds, zebras are active, noisy, and alert to their
surroundings -- and conspicuous to predators. In addition, groups of zebras often rest in exposed
areas, for example, on top of open, grassy hills. Although these locations provide good vantage points
to see approaching predators, they also cause the zebras to stand out conspicuously against the
horizon. Finally, zebras never attempt to conceal themselves or to freeze in response to predators,
which many animals with camouflage coloration attempt to do.
Explanation 2: Zebra stripes act as visual stimulation that causes zebras to maintain their
social behavior, inciting zebras to seek each other, stand together, and touch and groom one
another.
Zebras are extremely social animals. They congregate in herds that range in size from two to 20
individuals. (The size of the herd depends on the species of zebra, the environmental conditions of
climate, and the availability of water and food.) In these herds, zebras interact a great deal. For
example, scientists commonly observe zebras grooming, jostling, nipping, nibbling, conducting mock
battles (between young males), and exhibiting a variety of playful behaviors. Although some of the
zebras' behaviors appear to serve no purpose, some scientists have suggested that such behaviors
increase the overall cohesion among the zebras in a herd, thus increasing the survival of individuals.
(For example, zebras in herds -- especially young zebras-- might be less susceptible to attack from
predators.) Some scientists have hypothesized that variations in stripe patterns allow the infant zebra
to identify its mother. Other scientists have suggested that the specific bond between the infant and
its mother develops more as a result of chemical signals. As the young foal grows older, these
contacts become more frequent and are not restricted only to the mother. Other scientists who have
studied the visual abilities of different mammals have found that several types of nerve cells in the
brain are excited by crisp black and white stripes. These are the nerve cells that detect contrasting
tones, linear orientation of objects, edges, and the flicker effect of moving edges.
Some scientists have inferred from this evidence that a zebra within its herd cannot escape the visual
stimulation of the stripes. Some evidence suggests that zebras actively seek this visual stimulation. In
addition, zebras also respond in a similar manner to artificially striped panels.
African Zebras - Explaining the Zebra's Stripes
Zebra
CHARACTERISTIC
Grant's
Grevy's
Chapman's
Mountain
185-260 kg
(408-573 lbs)
290-335 kg
(639-739 lbs)
185-260 kg
(408-573 lbs)
224 kg
(494 lbs)
Average Height of 127-140 cm
full-grown adult
(50-55 in)
(at shoulder)
150-152 cm
(60 in)
127-140 cm
(50-55 in)
120-130 cm
(47-51 in)
Environment
Open grassy
plains or grassy
woodlands
Arid grasslands
and brushlands,
steppes
Open grassy
plains or grassy
woodlands
Dry, stony plains
mountains and
hills, sometimes
into deserts
Social Structure
Live in herds of 5
to 20 individuals;
herds congregate
and migrate
during dry season
Interbreed with
Chapman's zebras
Live in herds of 4
to 14 individuals;
males may be
solitary
Average Mass of
full-grown adult
Ability to breed
with other zebras
Live in herds of 5
to 20 individuals;
herds congregate
and migrate
during dry season
Do not interbreed Interbreed with
with other zebras Grant's zebras
Live in herds of 7
to 12 individuals;
males may be
solitary
Do not interbreed
with other zebras
Feeding Patterns
Nomadic grazers that eat coarse grasses; they congregate and disperse in
response to changes in weather, and water and food availability.
Other behaviors
All zebras are active, noisy, and alert. They don't attempt to conceal
themselves, nor do they freeze in response to predators. Often groups of
zebras rest in places where they have a good view of surrounding areas and
where they are conspicuous.
Chapman’s Zebra
Grant’s Zebra
Grevy’s Zebra
Mountain Zebra