Although the algae in no way harmed the animals, zoo veterinarian Phillip Robinson restored the bears' white fur by killing the algae with a salt solution.
The fur on a polar bear cub is whiter than that of adult bears. In older bears, fur colors range from white to almost yellow.
Hybrid cubs born to captive polar bears and their close relative, the brown bear, are white at birth but later turn blue-brown or yellow-white.
A polar bear is so well-insulated that it experiences almost no heat loss. In addition to its insulating fur, the bear's blubber layer can measure 4.5 inches thick.
So effective is the polar bear's insulation that adult males quickly overheat when they run.
Because polar bears give off no detectable heat, they do not show up in infrared photographs. (Infrared film measures heat.) When a scientist attempted to photograph a bear with such film, he produced a print with a single spot--the puff of air caused by the animal's breath.
