Polar Bear
Polar bears or Ursus maritimus, also referred as white
bears, northern bears, or sea bears, is a large bear
due to its big and heavy size. It is found throughout
the Arctic surrounding the North Pole. Their fur and
thick blubber is like an insulator against the cold,
and this is the main reason they are able to live in
such chilling conditions. Their name Ursus maritimus
means maritime bear, which leads to some beliefs that
these are marine mammals.
There are six different populations of polar bears,
namely Wrangel Island and western Alaska, northern Alaska,
the Canadian Arctic archipelago, Greenland, Svalbard-Franz
Josef Land, and Central Siberia. However, their range
is limited by the availability of sea ice, which is
used as the major platform to hunt seal by these species.
Polar bear is large like brown bear and is twice the
weight of a Siberian tiger. The weight of a male polar
bear ranges between 300 to 800 kg, while a female weighs
from 150 to 300 kg, and the weight of a newborn cub
ranges from 600 to 700 grams. The height of an adult
is about 1.6 m up to the shoulders and the males are
2.5 m long from the neck to the tip of tail, while females
are about 1.8 to 2 m long.
The forepaws are broad and are used as perfect paddles
while swimming, as these are believed to be excellent
swimmers. Polar bear are capable of hunting both on
land and in sea. The soles of all the four paws are
furred to provide insulation against cold while walking
on ice. The skin of polar bears is actually black, while
the fur is actually clear, and the white appearance
of the species is due to the reflection by the clear
fur.
Mating usually occurs in late winter or early spring.
The mating lasts for a little, i.e., around 3 days and
the gestation period including delayed implantation
is about 8 months. The cubs are born in November to
January, while the mother is hibernating in the den,
which she prepared by digging deep in the ice for hibernation
during October. A litter may be of 1 to 4 cubs, but
usually there are two cubs, which are small as compared
to other cubs and are blind, which will open their eyes
after one month. The cubs stay with their mothers in
the den about three months and in April they emerge
from their dens. Mothers provide all the parental care
to the cubs while their stay. Before being independent
the cubs remain with their mother for about 2 to 3 years.
Except for breeding and during the nursing of cubs,
polar bears are solitary animals and they may attack
other bears for food. Polar bears eat as much as they
can in the summer so as to sustain while hibernation
in winters; and the mothers will be surviving only on
the fat they had, along with their little cubs. The
polar bear mostly rely on seals; especially ringed seals
to feed themselves. However, anything they can kill
can be their food, such as birds, and shellfish, etc.
Further Reading
Polar Bears International:
http://www.polarbearsinternational.org
The Smithsonian Institution's North American Mammals
website:
http://www.mnh2.si.edu/education/mna/image_info.cfm?species_id=418
Arkive
http://www.arkive.org/species/GES/mammals/Ursus_maritimus/more_info.html
Animal Diversity Web
http://animaldiversity.ummz.umich.edu/site/accounts/information/Ursus_maritimus.html
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