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.
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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
In 1949, an official boxing match between a bear and a man was held. The bear won.
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Leonardo Da Vinci loved animals so much that he used to buy caged animals at the market just to set them free.
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Some lizards, in which the tail is a major storage organ for accumulating reserves, will return to a dropped tail after the threat has passed, and will eat it to recover part of the sacrificed supplies.
13
Blue whale arteries are large enough for humans to swim through and their hearts are the size of cars.
12