Your lungs work like bellows: air flows in and out along the same path, and some of it stays stale. In birds, a system of air sacs pushes air through the lungs in the same direction, whether breathing in or out. The result is a far more efficient oxygen supply, allowing some species to fly at altitudes where you would struggle to walk.
In 2022, a young tagged bar-tailed godwit flew from Alaska to Tasmania in about 11 days of nonstop flight, covering 13,560 km without eating, drinking or landing. Before departure, these birds pile on huge fat reserves and shrink their digestive organs, which are useless during the journey.
To escape rivals, a dung beetle rolls its ball of dung in a straight line. At night, it holds its course using the glowing band of the Milky Way. In a planetarium, researchers showed that beetles rolled straight under a starry sky but wandered aimlessly when the galaxy was switched off. It was the first animal known to navigate this way.