Dolphins Never Forget Their Friends

Not only do dolphins mourn their dead, call each other by distinct names, protect their faces with sponges and recognize themselves in mirrors, but now a new study reveals that dolphins have phenomenal memories. Even after being separated for 20 years, dolphins remember their tank mates’ whistles.

Research published in February found that dolphins have unique signature whistles which they use to address those they are close to. Scientists had previously observed that dolphins emit unique whistles to identify themselves to other dolphins. Jason Bruck made the latest discovery about dolphins, that they have long-term social memories, while doing research for his Ph.D. in the University of Chicago’s program in Comparative Human Development.

Bruck drew on data kept on 53 different bottlenose dolphins at six facilities that are part of a breeding consortium through which dolphins are rotated. The facilities have kept records that go back decades about which dolphins had lived together.

To get a sense of how dolphins responded to whistles that were familiar to them versus those made by dolphins whom they did not know, Bruck played recordings of whistles from unfamiliar dolphins to the animals he was studying. Dolphins, he notes, “get bored quickly listening to signature whistles from dolphins they don’t know.” But when Bruck played a whistle from a dolphin who had been a former tankmate, the dolphin being tested would swim quickly over to the speaker and “hover around, whistle at it, try to get it to whistle back.”

One particularly notable example involved Allie, who currently lives at the Brookfield Zoo in Chicago, and Bailey, a female who now lives in Dolphin Quest in Bermuda. Allie was two and Bailey was four when they had last been together, at Dolphin Connection in the Florida Keys. While twenty years and six months had passed since they had been together, Bailey recognized Allie’s whistle.

Bruck’s study shows that dolphins have memories that are the longest in a non-human species (elephants have been found to remember their mothers after 20 years). He speculates that dolphins may have evolved the ability to have such long memories because of the social connections they form; in the open ocean, dolphins break apart from one group and “fuse” or join with other groups many times over. Or, their memory could be just yet another “facet of the advanced mind that evolved in dolphins for other reasons.”

As Bruck acknowledges, his research was carried out on captive dolphins; he says that it would be “almost impossible” to conduct a similar study in the wild as it was necessary to know how long the dolphins had been apart from each other. Bruck’s findings offer yet another reason to take into account how dolphins in captivity are affected emotionally and otherwise by an experience none of us would want to be in. A dolphin rushing to a speaker when he or she heard a familiar whistle — the sign of a friend last heard two decades ago — suggests how much it might mean for long-separated dolphins like Allie and Bailey to be reunited.

Bruck’s study also offers further evidence, as one Emory University professor has argued, that dolphins — and, whales, elephants and chimps (who also hold on to their memories just as we do) — deserve human rights because of their highly developed cognitive, emotional, social and other abilities.

Can you remember the sound of someone’s voice from 20 years ago?

Photo from Thinkstock


Jim Ven
Jim Ven2 years ago

thanks for the article.

stacey wallace
stacey wallace4 years ago

More reasons why they shouldn't be kept in captivity or slaughtered in taiji.

Mark D.
Mark D.4 years ago

I'm praying every day that a tsunami wipes out the entire dolphin murdering town of Taiji. They are nightmarish monsters that don't deserve to live.

Waheeda S.
Waheeda E4 years ago

Incredible creatures! Just one more reason why they should not be slaughtered or even captured for captivity.

Sherry C.
Sherry C4 years ago

I bet all animals don't forget their "friends"s

Grace K.
Grace Kennedy4 years ago

It's wondrous and sad. Dolphin intelligence and loyalty are truly inspiring. Our treatment of these magnificent creatures is shameful.

Sandi C.
Sandi C4 years ago

Dolphins are awesome.

Julia Troitskaia
Julia Troitskaia4 years ago

Always loved dolphins. They are even very cute. Always smiling. And another fact about dolphins: they even engage in sex for pleasure, not because of instinct. Such animals can be counted on the fingers. And more... Recently, India went behind Hungary, Costa Rica and Chile... Now, only in these three countries whales are officially recognized by intelligent beings and prohibited as entertainment.
"Cetacean should be seen as individuals with their own rights and therefore morally unacceptable to keep them in captivity - a new decision of the government of India, which is a landmark decision taken an important first step in creating a global animal rights."
"Research oceanographers showed that cetaceans have large brains and complex behavior, complex communication systems, communication and learning. Dolphins are very intelligent mammals with highly developed social structure. Dolphins call each other by name, choose their own unique names - a series of complex high-pitched sounds - until they reach the age of one year. From this point on, all the other dolphins in their social group call them this unique name, using highly complex grammatical relations."
Mentally, I just rays of goodness and sent them to the Government of India.

Mari s
Mari 's4 years ago

Dolphins not only do not forget they even call each other by name. We must save them from these monsters that have no empathy.

Mari s
Mari 's4 years ago

I don't understand how some people can be so barbaric and cruel. Animals have rights too all of them. I think it's very selfish to not consider their lives as equal if not even more so Important. Stop the animal holocausts!!! End the wars on animals!!