A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
Parrotfish make themselves a kind of mucus 'sleeping bag' which masks their smell from predators and keeps parasites away.
4
The Basenji dog is the only dog that is not able to bark.
4
Urechis unicinctus is a species of marine spoon worm that is widely referred to as the ‘penis fish’.
2
Squirrels forget where they hide about half of their nuts.
698
Cows as they are today never existed in the wild and were domesticated from aurochs some 10,500 years ago.
6