Cats recognise the voice of their owner, but never evolved to care.
22
Sharks, like other fish, have their reproductive organs in their chests.
248
When Washoe, the first chimp to use sign language, was told that her caretaker's baby had died, she signed "CRY."
20
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
Vampire bats adopt orphans, and are one of the few mammals known to risk their own lives to share food with less fortunate roost-mates.
402