Dolphins sometimes have fun by blowing bubbles and creating rings of air underwater, which they then swim through.
17
During World War 1, starving wolves amassed in such great numbers that Germans and Russians had a temporary cease fire to fight off the wolf attacks.
45
When dragonflies mate, their tails form a love heart.
22
When Washoe, the first chimp to use sign language, was told that her caretaker's baby had died, she signed "CRY."
20
A group of unicorns is called a blessing.
304
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
Parrotfish make themselves a kind of mucus 'sleeping bag' which masks their smell from predators and keeps parasites away.
4