The world's largest mammal, the blue whale, weighs 50 tons at birth. Fully grown, it weighs as much as 150 tons. The heart of a blue whale is as big as a car, and it's tongue is as long as an elephant.
At 188 decibels, the whistle of the blue whale is the loudest sound produced by any animal.
More Animals Facts
A cow gives nearly 200,000 glasses of milk in her lifetime.
The hippopotamus gives birth under water and nurses its young in the river as well, though the young hippos do come up periodically for air.