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Polar Bear (Ursus maritimus) Fact Sheet: Physical Characteristics

Physical Characteristics

Attribute Male Female
Body Weight Occasionally exceed 800 kg (1,764 lbs) 150-250 kg (331-551 lb)
Shoulder Height Up to 1.7 m (5.6 ft)* Up to 1.7 m (5.6 ft)*
Body Length 240-260 cm (95 -102 in) 190-210 cm (75 -83 in)
Tail Length 7-12 cm (about 3-5 in) 7-12 cm (about 3-5 in)

*Alaskan brown bear nearly the same size

General Appearance

Largest living bear species

  • Occasionally exceeds 800 kg (1,764 lbs)
  • Lack shoulder hump.

Head and mouth

  • Neck is long and very thick (wider than the head); radio collars slip off males - only used on females.
  • Head is elongated but smaller than that of other bears.
  • Dentition reflects a strictly carnivorous diet.
  • Cheek teeth surface area reduced (few plants to grind).
  • Slicing teeth (carnassials) are well-developed for meat eating.
  • Canines elongated, conical and slightly hooked for grasping prey; male canines very large.
  • Ears relatively small.
  • Sensitive hearing over a wide frequency range; respond to Ringed Seals low-frequency vocalizations.

Feet and claws

  • Large paddle-like, wide feet.
  • 5 toes on each foot.
  • Claws non-retractable and are 5-7 cm long.
  • Soles of feet have small dermal bumps or papillae which may help with traction on ice.

Misc. characterisitics

  • Females have four functional mammae (other bears have 6).
  • Large amounts of sub-cutaneous fat.
    • Adult thickness 5-10 cm.
    • Both blubber and pelt provide insulation
  • Liver is somewhat toxic to humans due to its high levels of vitamin A. (Amstrup 2003)
  • Able to avoid bone loss during prolonged, continuous hibernation (Amstrup 2003)
    • A unique physiological adaptation for bone building allows a "protective preparation" for hibernation.

Sexual Dimorphism

  • Substantial sexual dimoprhism
    • Males 2.1 times mass of females
  • Males have much longer foreleg guard hairs than females
    • May be attractive to females (as is the male lion's mane), or may make the males look larger to other males.
  • Sex ratio
    • Three adult males for each breeding female = strong competition for females

Other Characteristics

Pelage and Skin

  • Completely covered with fur except for tip of nose; even foot pads are furred in winter.
  • Have thick layer of underfur (5 cm long) and tufted intermediate guard hairs (15 cm long)
  • Distinctive translucent white hair is unpigmented.
    • Probably arose from light color phase brown bears that were living on Asian coast of Arctic Ocean.
    • Color varies with season. Appear whitest after molt, yellowish in summer due to oxidation by sun or oils from prey
    • Hairs do not transmit UV light to the skin in order to capture heat energy from the sun (a 1980's "Arctic legend") (Amstrup 2003)
    • Algal growth inside the shaft of hollow guard hairs of bears raised in managed care in warm climates causes the pelt to have a green appearance.
  • Nose, skin, and claws are black

Covered in Fur

Polar bear black paws and nose

Polar bear black skin

Nose, skin, and claws are black. Foot pads are furred.

Image credit: © San Diego Zoo Global. All rights reserved.

Page Citations

Amstrup (2003)
Cushing et al (1988)
DeMaster & Stirling (1981)
Derocher et al (2005)
Kurt (1990)
Nachtigall et al (2007)
Stirling (1993, 1998)

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