A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
The cat brain weighs about 30g.
167
Cats sleep for 70% of their lives.
8
Bats sleep 18-20 hours per day.
5
There was a bear called Wojtek who was adopted by Polish soldiers during WW2. It carried ammunition, wrestled with soldiers, and drank beer.
40
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