Video Transcript
The polar bear has many adaptations
to help it hunt on the ice in the Arctic. Due to global warming, the sea ice
is rapidly melting. What is most likely to happen to
the polar bear? (A) It will quickly adapt to
hunting in the sea. (B) The polar bear’s diet will
change, and it will eat plants instead. (C) It will not be able to hunt,
and populations will die out. Or (D) polar bears will start
hunting in groups rather than individually to improve their chances.
This question is asking about the
likely effects of global warming on polar bear populations. To answer this question correctly,
let’s review some key facts about adaptations and what happens when the
environmental conditions where an organism lives changes. But what do we mean by
adaptations?
An adaptation is a characteristic
that an organism has in order to make it well suited to its environment and to give
it a better chance of survival. Adaptations evolve over many
generations and can take thousands of years to come about. In order to survive, an organism
needs to avoid predators, be able to obtain food, and be able to thrive in the
environmental conditions of their habitat. Adaptations help an organism with
these challenges.
Camouflage is an adaptation that
helps an organism conceal itself by blending in with its surroundings. In this picture of the polar bear,
you can see their white coat helps them blend in with the background of snow and
ice. Adult polar bears have no natural
predators in the Arctic so usually do not rely on their white coat to hide for
protection. The bear cubs which are more under
threat from some carnivores, such as wolves and indeed adult male polar bears, will
benefit in this way. For the adults, the white fur is
beneficial to them as it enables them to sneak up on their prey, and so they are
more successful in their hunt. This, therefore, enables them to
obtain more food for themselves and any young.
The Arctic is a harsh environment,
with extremely cold temperatures and short summers. The polar bear has therefore
developed some structural adaptations to enable it to cope with these
conditions. Fat under the skin provides
insulation against the cold, and polar bears have a deep layer of it. This, added to the thick fur coat,
helps keep the polar bear warm. The fur is also covered in oil,
which helps them shed the water after swimming, and this also helps maintain
warmth.
Global warming means the Earth’s
temperature, and hence the temperature of the Arctic, is increasing. This means that although air
temperature is still extremely cold, the ice platforms that the polar bears hunt
seals from are melting. This is happening at an alarming
rate, meaning the environment is changing much more quickly than the polar bear can
adapt.
Looking at the catching of seals to
feed on, polar bears can eat other food, including fish they catch in the sea. Unfortunately, however, most seal
alternatives, including the option of eating plants, would not provide them with
enough energy to sustain the important fat layers under their skin. So, option (B) can be ruled out of
the possible answers.
Because adaptations take so long to
develop and the ice is melting so quickly, the polar bear cannot develop to be like
marine mammals, such as seals, quickly enough to provide themselves with food. This means that answer option (A)
can also be ruled out.
The need for energy is also the
reason for polar bears being solitary animals. They live in their territory on the
ice, which usually provides just enough food for them and any cubs they may have,
although they have to work hard to catch it. If they hunted in packs, they would
need a vast, reliable food supply to provide enough energy for all the polar bears
in the pack. This amount of food is just not
available in one area in the Arctic. And so, the pack of bears would
perish from lack of energy. Therefore, option (D) can also be
removed.
Now that we have reviewed the fact
that adaptations take a very long time to develop, often thousands of years, and
that climate change is happening much more quickly than this, we can return to our
question. We now know that the correct answer
is option (C). The most likely effect of global
warming on the polar bear is that it will not be able to hunt, and populations will
die out.
