The harsh conditions of the high altitudes, force
polar bears to adapt to the their environment. Many of the
adaptations seen in polar bears help to regulate body temperature, make
hunting easier, and increase the efficiency of movement both in and out of
the water. The polar bear's thick curved claws are important
during times of feeding. They are frequently used to tear away the
flesh of preyed upon organisms and to navigate through the carcasses of
dead animals. The polar bear's distinct swimming abilities
probably source from their joined toes (webbed feet). Their toes are
joined by swimming membranes which allow for greater success in the
water (Macdonald, 500). Another important characteristic of the
polar bear is its water repellant fur coat (Kurt, 500). This
feature allows for more efficient and less exhausting swimming.
Although a seal can easily out swim a polar bear, seals are easily
tricked by polar bears because their depth perception is rather poor.
For example, Adrian Forsyth a researcher from Mammals of North
America explains,
"One polar bear was seen pretending to be an ice chuck while he stalked
an adult ringed seal in open water. First observed about 230 feet
from a seal resting on ice, the bear began swimming strongly toward it.
Whenever the seal went underwater, the bear immediately stopped swimming
and floated motionless; when the seal surfaced, the bear resumed its
swim, gradually closing the distance between them. Finally, the
seal surfaced right beside the bear, apparently mistaking it for
floating ice. The bear killed it with a sudden lunge and a single
bite."
This image above was taken from Microsoft clip
art. It illustrates the bear's adaptive winter coat and its
morphological features.
The polar bear's heavy coat is a
very important adaptation used
in body temperature regulation. The color of polar bear's fur
changes annually; during the winter, after the summer molt, polar
bear's fur appears pure white, whereas, during the summer its fur seems
to have a yellow tint to it. The molting process allows polar
bears to shed their winter coat and aids in keeping them cool during the
warmer summer months. The polar bear's pure
white coat creates a camouflage effect and serves as an important
mechanism during hunting. In addition, the polar bear's fur coat acts as a
heater or solar collector as the hollow hairs trap in warm insulating
air from the sun (Forsyth, 190). Interestingly, the skin underneath the polar
bear's coat is black (Geist and Kleiman, 304). Because dark
colors absorb heat, this adaptation provides additional warmth when the
sun is shinning. Polar bears are able to obtain extra warmth from
their diet; the
high fat content that polar bears consume during meal time serves as
insulation during the cold winter months. Diets high in fat are an
essential part of polar bears survival. Without the extra fat from
their diet, they would not be able to fast and function without food for long periods of
time. The fatty meat that polar bears consume gives them extra
food when the food supply is low or weather conditions are harsh. With the exception of the polar bear's black nose and foot
pads, it is entirely covered with fur. Being fully clothed
provides the polar bear with additional warmth during the winter.
As mentioned before, polar bears have
mammary glands which produce milk
for their newborn cubs. The milk secreted by the mammary glands
contains nearly 31 percent fat (Macdonald, 92). The high fat
concentrated milk helps regulate the baby cub's body temperature and
ensures rapid growth and development.
In addition to the
adaptations used in temperature regulation, the polar bear also has a keen sense of smell and very good
eyes sight; both very important features when hunting in the arctic habitat.
Often times, polar bears use their vivid sense of smell to locate
their next victim. The polar bear appears to be slightly
bowl-legged and pigeon-toed. These adaptations allow the polar
bear to travel at high speeds and stop abruptly without slipping on the
slippery ice. The soles of the feet are haired and give the polar
bear more traction when running and making sudden movements on the ice.
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