Hi there!
1. Whales don`t extract oxygen from water:they come to the surface of the water and breathe air.
2. Whales can hold their breath between 5 minutes and one hour under the surface of the sea.
3. Whales don`t sleep completely, they onlyrest, half asleep, close to the water surface.
4. When resting, whales use half of the energy they use when they are active.