A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
When Washoe, the first chimp to use sign language, was told that her caretaker's baby had died, she signed "CRY."
20
Urechis unicinctus is a species of marine spoon worm that is widely referred to as the ‘penis fish’.
2
A group of kittens is called a "kindle".
10
Leonardo Da Vinci loved animals so much that he used to buy caged animals at the market just to set them free.
57
Blue whale arteries are large enough for humans to swim through and their hearts are the size of cars.
12