Dolphins are known to be one of the most intelligent animals on Earth, living in highly social groups and displaying empathy, self-awareness, problem-solving skills and tool use.
They communicate using a sophisticated array of clicks, body language and whistles, with “signature whistles” (SWs) serving as names for individuals.
Recent research by scientists with the Woods Hole Oceanographic Institution (WHOI) and partner institutions has identified possible language-like communication among dolphins.
Their research focused on “non-signature” whistles (NSWs), which the researchers found to potentially function like words in communications between multiple dolphins. NSWs have received less research attention than the name-like vocalizations of SWs.
“Bottlenose dolphins have long-fascinated animal communication researchers,” said biologist Laela Sayigh, leader of the WHOI research team, in a press release from the institution. “Without the over five-decade-long study by the Sarasota Dolphin Research Program, we would not have such an extensive library of vocalizations for individual dolphins. With this, we can study non-signature whistles, which have received very little research attention to date. Our work shows that these whistles could potentially function like words, shared by multiple dolphins.”
Check out this piece on some of our latest findings on dolphin communication, in research led by our colleague Laela Sayigh.
— Frants Jensen (@frantsjensen.bsky.social) May 22, 2025 at 10:50 PM
The WHOI team and partner institutions, including the Brookfield Zoo Chicago’s Sarasota Dolphin Research Program (SDRP), were the winners of the first Coller Dolittle Challenge for their work.
NSWs make up roughly half of the whistles produced by dolphins living in the waters around Sarasota, Florida.
“Signature whistles are individually distinctive whistles that function much like human names. Non-signature whistles are all whistles other than signatures. We have only very recently started studying them and know very little about them, but we have found evidence for widespread sharing of a variety of stereotyped non-signature whistle types,” Sayigh told EcoWatch in an email.
The research team used playback experiments in the wild to identify distinct types of NSWs used for communication by multiple dolphins.
“We have been studying the possible functions of some shared, stereotyped non signature whistle types, including NSWA. We found that this whistle type typically elicits avoidance responses, leading us to believe that it may have an alarm-type function,” Sayigh told EcoWatch.
The researchers found another NSW that they correlated with a “query” function — “NSWB” — produced by the dolphins in response to an unfamiliar or unexpected situation.
“We first observed NSWB as a response to NSW playbacks, which were likely unexpected in the context that they were presented. Later we also observed them to be produced by a pair of males in response to unexpected playbacks of their own signature whistles. This led us to suggest that this whistle may be produced in response to an unexpected stimulus, perhaps as a way of inquiring what it is,” Sayigh explained.
The team placed digital acoustic tags and non-invasive suction-cup hydrophones on the dolphins during catch-and-release health assessments to record known individuals.
“We have built a unique library of sounds produced by known individual common bottlenose dolphins (Tursiops truncatus),” the authors wrote in the study. “We have catalogued the name-like signature whistles (SWs) of most animals in this resident community of 170 dolphins, which has enabled us to begin studying little known ‘non-signature whistles’ (NSW). We have so far identified 22 shared NSW types, of which two, NSWA and NSWB, are known to have been produced by at least 25 and 35 different dolphins respectively.”
The authors said that, since SWs and SW copies appeared to be referential signals, and are already known to be learned, it is likely that stereotyped and shared NSWs are also referential and learned.
This is “an idea that is supported by the fact that dolphins are flexible, life-long vocal production learners, unlike most other non-human mammals,” the authors wrote. “Our study provides the first evidence in dolphins for a wider repertoire of shared, context-specific signals, which could form the basis for a language-like communication system.”
Sayigh told EcoWatch that the research team has so far “only suggested” that NSWs “may be word-like, in the sense that they may have specific meanings that are understood by multiple animals. However, this is only a hypothesis at this stage.”
Sayigh said the team is currently trying to understand how dolphins use NSWs to communicate.
“We have so far only tested responses to NSWA and NSWB. Responses to playbacks of NSWB have been variable, which could support a variety of functions, including our suggested function as a query,” Sayigh said.
The study, “First evidence for widespread sharing of stereotyped non-signature whistle types by wild dolphins,” is available on the bioRxiv preprint server.
“Humans share this planet with millions of other species, but for far too long we’ve only talked among ourselves. The Coller Dolittle Challenge aims to change that, so I’m excited by the fascinating work Laela and her team have done on dolphin communication. They are worthy winners and I can’t wait to see how they use AI to further interpret this vast set of data,” said Jeremy Coller, founder of the Coller Dolittle Challenge, in the press release.
This article by Cristen Hemingway Jaynes was first published by EcoWatch on 10 July 2025. Lead Image: Four long-term resident mother-calf dolphin pairs swim off the coast of Sarasota, Florida. Randy Wells / Sarasota Dolphin Research Program.
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