Like many mammals, reindeer have a reflective layer at the back of the eye, the tapetum lucidum. In summer, under the midnight sun, it is golden and bounces light straight back out. During the long polar night it turns deep blue, scattering more light within the retina, which appears to boost sensitivity at the cost of a slightly blurrier image.
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.