Just like humans call out to one another using each other’s names, dolphins have a signature whistle they use to identify themselves.
According to a new study, dolphins can remember the whistles of their fellow dolphins after being separated from their tanks for more than 20 years. According to the research, no other species other than humans have such long-term social memory.
Dolphins have normal whistles, then they also have signature whistles, which they develop to function like a name. When a dolphin comes in contact with another dolphin it will use this signature whistle as a way of announcing its identity.
“Dolphin long-term memory has been difficult to study,” said Jason Bruck, a biologist with the University of Chicago. “Mostly we have anecdotal evidence of dolphins’ long-term memory, such as how they can remember trained behavior for a few years.”
Bruck’s interest is about a dolphin’s social memory, rather than sematic memory and episodic memory.
“In a social species, it may be the case that social memory is really important, but we don’t know yet because it is poorly studied,” Bruck told i09. “We also don’t know yet how it related to episodic and other forms of memory."
For his study, Buck took 43 dolphins from a variety of facilities, including the Brookfield Zoo near Chicago, the Minnesota Zoo and the Seas at Walt Disney World. All of the dolphins were part of a breeding program that rotated animals between the institutions, allowing the dolphins to become familiar with different individuals over time, according to io9.
What he found was that when he played a recording of a signature whistle, the dolphins would often quickly approach the loudspeakers, make eye contact with it and even at times whistle at it.
According to i09, Bruck compared the experiment to what would happen if a person saw a realistic hologram of someone they knew.