Cleaner wrasse quickly learn to recognize themselves in mirrors, and take advantage of the information their reflection provides. They also experiment with the mirror in a way we might call playful, ...

Cleaner wrasse have revealed a remarkable new side of fish intelligence. Marked with fake parasites, they used mirrors to inspect and remove the spots—far faster than seen in earlier tests. Even more ...

In the new experiment, roosters made fewer alarm calls, meant to warn peers of predators, when placed in front a mirror versus when standing near another rooster. Stefano Spaziani / picture alliance ...