A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
A koi fish, named "Hanako", was owned by several individuals over many years and lived to be 226 years old, dying in 1977.
6
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
The Savannah is the largest domestic cat breed. It resembles a small leopard and behaves like a dog. They can grow up to 40 lbs, have an eight foot vertical jump, and can be trained to walk on a leash and play fetch.
17
Tigers can see 6 times better at night than humans.
305
Parrotfish make themselves a kind of mucus 'sleeping bag' which masks their smell from predators and keeps parasites away.
4
Sergeant Stubby was the only war dog to be promoted to sergeant through combat in WWI. He saved his regiment from surprise mustard gas attacks, found and comforted the wounded, and even once caught a German spy by the seat of his pants, holding him there until American Soldiers found him.
16