In theory, a reaction to an out-of-place mark in a reflection is assumed to be evidence of self-recognition for other animals as well. Chimpanzees, elephants, and dolphins are just some that have ...

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 ...

A small coral reef fish can recognize itself in a mirror. This discovery challenges long-held ideas about animal intelligence.

Learn how cleaner wrasse used a mirror and even dropped food to test their reflections, a behavior linked mostly to mammals.