A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
Dolphins can rapidly heal from extreme injuries, such as shark bites, and regenerate their original body shape.
19
One reason that kittens sleep so much is because a growth hormone is released only during sleep.
212
Cats are one of the only animals to domesticate themselves and approach humans on their own terms.
20
Sharks have been on the planet longer than trees.
14
Urechis unicinctus is a species of marine spoon worm that is widely referred to as the ‘penis fish’.
2