Which animal has the longest memory?

You might remember the saying "an elephant never forgets," but you should really be aiming for a memory like a dolphin. A 2013 study from the University of Chicago found that bottlenose dolphins hold the record for the longest memory in the animal kingdom. Each dolphin develops a unique "signature whistle" that functions like a name, and when researcher Jason Bruck played recordings of old tankmates through underwater speakers, dolphins that had been separated for decades immediately perked up, approached the speaker, and whistled back. Meanwhile, most of us show up to our high school reunions and spend minutes looking at someone's face before we recognize them.