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Polar Bear (Ursus maritimus) Fact Sheet: Physical Characteristics

Physical Characteristics

Attribute Male Female
Body Weight*

Typically 350–650 kg (770–1,430 lb);
very large males up to 800 kg (1,760 lb)

Typically 150–350 kg (330–770 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)

 

*from Whiteman (2021); "varies substantially throughout their annual cycle"

**Alaskan brown bear is nearly the same size.

General Appearance

Largest living bear species

  • Occasionally exceeds 800 kg (1,764 lb)

Head and mouth

  • Neck is long and very thick
    • In males, neck is wider than the head
  • Head elongated but shorter than many other bears
  • Dentition reflects a strictly carnivorous diet
    • Slicing teeth (carnassials) well-developed for eating flesh
    • Canines elongated, conical and slightly hooked for grasping prey
      • Male canines very large
    • Molar surface area reduced (infrequently chew plants)
  • Ears relatively small

Feet and claws

  • Wide feet
    • Large, paddle-like
  • 5 toes on each foot
  • Claws non-retractable
    • 5–7 cm long
  • Soles of feet have small dermal bumps or papillae
    • May help with traction on ice

Other characteristics

  • Large amounts of subcutaneous fat
    • 5–10 cm thick in adults
    • Both fat and pelt provide insulation
  • Experience little bone loss during prolonged, continuous denning period (Amstrup 2003)
  • Lack shoulder hump
  • Females have four functional mammae for nursing young
    • Other bears have 6
  • Liver tissue is toxic to humans, if consumed, due to its high levels of vitamin A (Amstrup 2003)

Sexual Dimorphism

  • Substantial sexual dimorphism (e.g., Derocher et al. 2005)
  • Males can be 2 times larger than females
  • Males have much longer foreleg guard hairs than females
    • May be used by females to select mates, or may make a male look larger to other males

Other Characteristics

Pelage and skin

  • Covered with fur, except for nose
    • Even foot pads are furred in winter
  • Thick underfur
    • 5 cm long
    • Tufted intermediate guard hairs (15 cm long)
  • Distinctive white hair
    • Translucent; no pigments
    • Color varies somewhat with season
      • Bears appear whitest after molt
      • Yellowish in summer due to oxidation by sun or oils from prey
    • Any green appearance from algae growing inside shaft of hollow guard hairs
      • More common in bears raised in managed care in warm climates
  • Black nose, skin, and claws

Vision

  • Likely possess color vision (Ronald and Lee 1981; Levenson et al. 2006)
    • More similar to other terrestrial bears than other marine mammals

Hearing

  • Sensitive over a wide frequency range
  • Respond to ringed seal's low-frequency vocalizations

Covered for the Cold

Polar bear black paws and nose

Polar bear black skin

Few parts of a polar bear's body lack fur. Even their foot pads may be furred during winter.

Image credit: © San Diego Zoo Wildlife Alliance. 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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