Savannah: Researchers think that whales have a neat trick to avoid getting the bends: They collapse their lungs when they dive. The bends are a side effect of surfacing from a dive too fast; they happen when there's too much nitrogen in you, and the air bubbles block your blood vessels.

And that's not great for whales that dive like every day. So instead of holding air in their lungs while they dive, they could shunt it into their upper airway - basically, their version of a nose - to keep it away from their blood. This way, models suggest that they can move air back to their lungs as they slowly move towards the surface so they don't get the bends.

And usually, that works great. But if they get startled and gasp, any air that reached their lungs could still give them the bends. So, diving takes focus, even for whales.

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