There are approximately 5,400 known mammal species on Earth.  All mammals have hair or fur, are warm blooded, give live birth and have mammary glands for nursing their young.  Of course, in the animal world nothing is absolute.  There is an unusual group of egg-laying mammals known as monotremes.  The smallest mammal is the Kittiā€™s hog-nosed bat, which only weighs 0.05 ounces and can sit on top of your finger.  The largest is the blue whale, which can be 100 feet long and weigh 150 tons.

Leopard   Greater one horned Asian rhino   North American River Otter   Cougar