Female kangaroos have three vaginas.
2
When cats are happy, they may squeeze their eyes shut.
10
Vampire bats adopt orphans, and are one of the few mammals known to risk their own lives to share food with less fortunate roost-mates.
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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
In 1918, a homing pigeon saved over 190 American soldiers by delivering a message to nearby support despite having been shot through the breast, blinded in one eye, covered in blood, and with a leg hanging on by just a tendon.
22
The oldest known animal in the world was 'Ming' the 405 year old clam, discovered in 2007.
492