Dolphins Have Longest Memories in the Animal Kingdom and can remember their friends after 20 years apart.

By Christine Dell'Amore, National Geographic News, August 6, 2013

Sorry, elephants: Dolphins have taken the top spot for best memory, at least for now.

New experiments show that bottlenose dolphins can remember whistles of other dolphins they'd lived with after 20 years of separation. Each dolphin has a unique whistle that functions like a name, allowing the marine mammals to keep close social bonds.

The new research shows that dolphins have the longest memory yet known in any species other than people. Elephants and chimpanzees are thought to have similar abilities, but they haven't yet been tested, said study author Jason Bruck, an animal behaviorist at the University of Chicago. (Also see "Chimps, Orangutans Have Human-Like Memory.")