Animals that navigate extreme conditions and environments have evolved to sleep in extreme ways — for example, stealing seconds at a time during around-the-clock parenting, getting winks on the wing ...

Every animal with a brain needs sleep — and even a few without a brain do, too. Humans sleep, birds sleep, whales sleep and ...

The octopuses eat the tissues in the jellyfish's body, or bell, and then pull the prey's stinging tentacles along behind them ...