A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
Sloths take two weeks to digest their food.
243
A cat rubs against people not only to be affectionate but also to mark out its territory with scent glands around its face. The tail area and paws also carry the cat's scent.
293
When a drone bee mates with a queen, its ejaculation is so powerful that it can even be heard by the human ear.
5
The oldest creature ever found was Ming the clam at an admirable 507 years old.
16
Lobsters have blue blood.
476