The Platypus used to be considered a myth like Bigfoot and the Yeti.
18
The largest breed of rabbit is the Flemish Giant.
65
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
Cats and dogs can hear ultrasound.
350
When a male gentoo penguin "falls in love" with a female penguin, he searches the entire beach to find the perfect pebble to present to her.
25
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
A dog's naked behind leaves absolutely no bacteria when pressed against carpet.
250
Allegedly, Chrysippus, the Greek philosopher, died of laughter after getting his donkey drunk and watching it try to eat figs.
47