Watch these cool videos! Get fun facts to share with your friends. (AD) Subscribe Get more Weird But True! Meet the Mammals! They're warm-blooded and hairy. Check out pictures, videos, and facts. Cheetah Fastest land mammal Lion See why these big cats rule. KANGAROO CAN LEAP 30 FEET! River Otter LOVES TO SLIDE! Watch more videos! Visit Nat Geo Kids on YouTube. Explorer Academy Play all the videos! (AD) Buy the book! Check out the beautiful pics. Cool Videos! Watch playlists on YouTube. Zany Zoo fun! Check out pics of playful animals.