© Dr. Galen Royer Frysinger
Polar Bears
Ursus maritimus
The polar bear (Ursus maritimus) is a
carnivorous bear whose native range
lies largely within the Arctic Circle,
encompassing the Arctic Ocean, its
surrounding seas and surrounding land
masses. It is a large bear, approximately
the same size as the omnivorous Kodiak
bear (Ursus arctos middendorffi). A
boar (adult male) weighs around
350–700 kg (772–1,543 lb), while a sow
(adult female) is about half that size.
Although it is the sister species of the
brown bear, it has evolved to occupy a
narrower ecological niche, with many
body characteristics adapted for cold
temperatures, for moving across snow,
ice and open water, and for hunting
seals, which make up most of its diet.
Although most polar bears are born on
land, they spend most of their time on
the sea ice. Their scientific name means
"maritime bear" and derives from this
fact. Polar bears hunt their preferred
food of seals from the edge of sea ice,
often living off fat reserves when no sea
ice is present. Because of their
dependence on the sea ice, polar bears
are classified as marine.
Males waiting for the ice on Hudson Bay