Cows can sleep standing up, but they can only dream lying down.
745
Shark corneas are used in eye transplants and shark bone marrow can be used to graft human bones.
132
Cats recognise the voice of their owner, but never evolved to care.
22
Travis was a chimpanzee who socialized with humans since birth. He could log onto a computer to look at pictures, watch TV using a remote control, brush his teeth, feed hay to his owner's horses, water plants, and learned the schedule of passing ice cream trucks.
11
The oldest recorded elephant lived for 82 years.
213
Blue whale arteries are large enough for humans to swim through and their hearts are the size of cars.
12
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
Allegedly, Chrysippus, the Greek philosopher, died of laughter after getting his donkey drunk and watching it try to eat figs.
47