The narwhal's long spiral tusk, which can exceed 2.5 meters, is a canine tooth that grows through the upper lip, mostly in males. It is laced with nerves and tiny channels open to the outside, suggesting it may work as a sensory organ. In medieval times, these tusks were sold for a fortune as unicorn horns.
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.