Cats recognise the voice of their owner, but never evolved to care.
22
A newborn Chinese water deer is so small, it can (almost) be held in the palm of a hand.
13
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
Using a remote-controlled camera, biologists caught dolphins getting high by sucking on puffer fish. They were even caught passing the puffer fish around.
23
Cats are one of the only animals to domesticate themselves and approach humans on their own terms.
20
If a vampire bat goes 2 days without drinking blood, they can die. However, well fed female bats will puke up blood and share it with other bats that they like in exchange for grooming.
13
Blue whale arteries are large enough for humans to swim through and their hearts are the size of cars.
12
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