Dolphins sometimes have fun by blowing bubbles and creating rings of air underwater, which they then swim through.
17
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
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
A koi fish, named "Hanako", was owned by several individuals over many years and lived to be 226 years old, dying in 1977.
6
Allegedly, Chrysippus, the Greek philosopher, died of laughter after getting his donkey drunk and watching it try to eat figs.
47