In the Carboniferous period, insects such as Meganeura, relatives of dragonflies, spread wings about 70 cm wide. A leading hypothesis links this gigantism to the air of the time, which likely held much more oxygen than today's 21%. Insects breathe through a network of tubes that limits body size, and extra oxygen would push that limit. A lack of flying vertebrate predators may also have helped.
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.