I'll try not to repeat any that have already been said...

A crocodile cannot stick it's tongue out

Every human spent about half an hour as a single cell

Antarctica is the only continent without reptiles or snakes

Tigers have striped skin, not just striped fur

Polar bear's fur is not actually white, but clear

The only land animal other than humans that cries is the elephant

We are about 1/4 inch taller when sleeping at night than in the day