When bats aren't flying, they often dangle from cave ceilings or the undersides of bridges. But why do bats sleep upside down? This topsy-turvy behavior may result from the evolutionary journey bats ...

Bats are not the only animals that hang upside down. You will also see sloths, parakeets, white-breasted nuthatches, chimpanzees, and many spiders doing it. However, bats are most famous for ...