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| SCIENTIFIC
CLASSIFICATION |
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| COMMON
NAME: |
polar
bear |
| KINGDOM: |
Animalia |
| PHYLUM: |
Chordata |
| CLASS: |
Mammalia |
| ORDER: |
Carnivora |
| FAMILY: |
Ursidae |
| GENUS
SPECIES: |
Ursus
(bear) maritimus (sea) |
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| DESCRIPTION: |
Polar
bears are the largest land carnivore. Adapted for
the cold, polar bears have a thick fur coat that
appears white in coloration, but is really translucent.
Their black skin color is readily apparent on the
nose, eyes, lips and footpads. In addition to their
size and color, polar bears may also be distinguished
from other bear species by their smaller ears, longer
necks and the lack of a dorsal hump in adults. |
| MALE |
Adult
male polar bears, called boars, are substantially
larger than adult females. |
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| SIZE: |
At
birth, cubs are about 30 cm (12 in.) long |
| MALE |
2.5-3
m (8.2-9.8 ft.) long |
| FEMALE |
2-2.5
m (6.6-8.2 ft.) long |
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| WEIGHT: |
Newborn
calves weigh about 454-680 g (16-24 oz.) |
| MALE |
350-650
kg (772-1,433 lb.) |
| FEMALE |
150-250
kg (331-551 lb.) |
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| DIET: |
Adult
polar bears need an average of 2 kg (4.4 lb.) of
fat per day to maintain their weight. Their diet
includes mostly ringed and bearded seals and also
includes other seal species, walruses, narwhals,
beluga whales, whale carcasses, fish, reindeer,
birds, eggs, berries and kelp. |
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| GESTATION: |
About
8 months; includes about a 4 month period of delayed
implantation |
| ESTRAL
PERIOD |
Females
are induced ovulators; mating triggers the release
of an egg for fertilization |
| NURSING
DURATION |
18-30
months (wean) |
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| SEXUAL
MATURITY: |
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| MALE |
About
6 years |
| FEMALE |
About
4 years |
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| LIFE
SPAN: |
Typically
15-18 years; some have lived over 30 years |
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| RANGE: |
Circumpolar
arctic |
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| HABITAT: |
Inhabit
Arctic sea ice, water, islands, and continental
coastlines |
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| POPULATION: |
GLOBAL |
Estimated
at 21,500-25,000 |
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| STATUS: |
IUCN |
Lower
Risk/Conservation Dependent |
| CITES |
Appendix
II |
| USFWS |
Not
listed |
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| 1. |
Adapted
for the cold, polar bears have a thick fur coat.
The coat of a polar bear can appear in a number
of color variations from pure white to creamy yellow
to light brown, depending on season and angle of
light. A polar bear's black skin absorbs heat from
the sun, helping it stay warm. In addition, the
long guard hairs of a polar bears coat can trap
a still layer of water in the under-fur and help
insulate the bear's body while submerged; acting
in a similar manner to a wetsuit. Polar bears also
possess a fat layer that can reach a thickness of
up to 11 cm (4.3 in.) This fat layer acts as an
energy reserve in times of low food availability
and possibly also aids in thermoregulation. |
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| 2. |
Polar bears are strong swimmers, paddling dog-style
with their partially webbed front paws while holding
their hind feet and legs flat like rudders. Scientists
have tracked polar bears swimming continuously for
100 km (62 mi.). On land they are capable of reaching
speeds of 40 kph (25 mph) while running in short
bursts. |
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| 3. |
Only female polar bears, especially pregnant females,
enter into a state of carnivore lethargy or "hibernation".
They do so from October or November through March
or April. During hibernation, the female's heart
rate slows from a normal resting rate of about 46
beats per minute to about 27 beats per minute. Females
also fast throughout hibernation, losing all or
most of their fat stores. Though hibernating females
sleep soundly, they are easily aroused. |
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| 4. |
Unlike
most other hibernators, female polar bears give
birth while hibernating. Sows give birth in their
dens from November through January. Typically, two
cubs are born. Cubs are born helpless with their
eyes closed, and appear hairless because of their
very fine fur. Cubs open their eyes within the first
month and begin walking at two months. At four to
six months of age, cubs emerge from the den. By
eight months, they weigh more than 45 kg (99 lb.). |
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| 5. |
For
more information about polar bears, explore the
polar
bear info book. |
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| Polar
bears at zoological parks provide opportunities
for the public to learn about these animals and
how human activities may impact their survival.
Scientists and specialists study polar bear biology,
including polar bear reproduction, birth and care
of young, and communication.
As
with other marine mammals found in the United
States, the U.S. Marine Mammal Protection Act
of 1972 protects polar bears.
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| |
|
|
|
Jefferson, T.J. Leatherwood, S. and M.A. Webber.
FAO Species Identification Guide. Marine Mammals
of the World. Rome. FAO, 1993. |
| |
|
Nowak, Ronald M. (ed.). Walker's Mammals of the
World. Vol. II. Baltimore: Johns Hopkins University
Press, 1991. |
| |
|
Parker, S. (ed.). Grizmek's Encyclopedia of
Mammals. Vol. IV. New York: McGraw-Hill Publishing
Co., 1990.
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| Reeves,
R. R., Stewart, B.S., Clapman, P.J., and J.A. Powell
(Peter Folkens illustrator). National Audubon
Society: Guide to Marine Mammals of the World.
New York: Random House, 2002. |
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| Reeves,
R.R., Stewart, B.S. and S. Stephen. The Sierra
Club Handbook of Seals and Sirenians. San Francisco:
Sierra Club Books, 1992. |
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| Reynolds
III, J.E and S.A. Rommel (ed). Biology of Marine
Mammals. Washington and London. Smithsonian
Institution Press, 1999. |
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IUCN
Polar Bear Specialist Group
http://pbsg.npolar.no/ |
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University
of Michigan - Animal Diversity Web
http://animaldiversity.ummz.umich.edu |
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