Polar Bears and Penguins-Switching poles!

Ok guys,
We know that Polar bears live only around the Arctic circle and Penguins in the Antarctic. (Some didn't know this till now!)

Considering that the environment is similar around both poles, why can't the Polar bears survive in the Antarctic and Penguins in the Arctic?

:shk:

P.S. (My gran'ma forgot to tell me this one while I was in third grade. Too late to ask her now!)





[edit on 6-4-2006 by mikesingh]