Animals' hair color?

i wonder why most animals in the north, especially in cold place, are white(many of them are pure white except penguins) and the animals in the south are mostly black or brown or colorful.

also, i know we, human, get dark skin in the south because of the sun's radiation. so the sun's radiation can also effect the animals' hair color?

Animals' hair color?

The sun's radiation doesn't so much affect animal's hair color. It's more a matter of inherited traits that allow the animal to blend in with the environment (light fur helps blend in with snow). With hares (rabbits), it can be a matter of phenotypic plasticity... in the summer a lot of hares are brown but their fur turns white during the winter. This change in phenotype (appearance) allows the hares to better live in their changing environment.

You don't often see humans hair color change naturally during the summer - brunettes don't sporadically become blonde with out the aid of hair dye, so hair pigmentation is governed differently from skin pigmentation.

Animals' hair color?

It's so they can blend into their enviroment.