They are widely considered to be some of the most charismatic animals in the ocean.
Now, it turns out that bottlenose dolphins actually “smile” at each other while surfing, chasing each other and play-fighting, according to a new study.
Until now, little is known about how this species, famous for its intelligence and playfulness, interacts during playtime.
But experts have finally revealed that these dolphins use the “open mouth” facial expression, comparable to a smile, to communicate during social play.
The researchers found that dolphins almost always used facial expression when they were in their playmate’s field of view, and the playmates responded by “smiling” at them a third of the time.
They are widely considered one of the most charismatic animals in the ocean. Now, it turns out that bottlenose dolphins actually “smile” at each other while they surf, chase each other, and play-fight, according to a new study.
“We have discovered the presence of a distinctive facial expression, the open mouth, in bottlenose dolphins, and we have shown that dolphins are also capable of mirroring the facial expression of others,” said lead author and evolutionary biologist Elisabetta Palagi, of the University of Pisa. , saying.
“The signals of open mouth and rapid mimicry appear repeatedly throughout the mammalian family tree, suggesting that visual communication has played a crucial role in shaping complex social interactions, not only in dolphins but in many species across the world.” over time.”
Dolphin play may include acrobatics, surfing, playing with objects, chasing, and fighting.
To investigate whether dolphins visually communicate joy, researchers recorded captive bottlenose dolphins playing in pairs and while playing freely with their human trainers.
They showed that dolphins frequently use the open-mouth expression when playing with other dolphins, but do not seem to use it when playing with humans or when playing alone.
Experts have finally revealed that these dolphins use the “open mouth” facial expression, comparable to a smile, to communicate during social play.
Dr. Palagi said that while some may argue that dolphins simply imitate the mouth expression of others by chance, “it does not explain why the probability of imitating another dolphin’s open mouth in one second is 13 times greater when the receiver actually sees the original expression. ‘
While only one open-mouth event was recorded during solo play, the researchers recorded a total of 1,288 “smiles” during social play sessions, and 92 percent of these events occurred during inter-dolphin play sessions.
The dolphins were also more likely to assume the open-mouthed expression when their faces were in their playing partner’s field of vision, and the team saw their playing partner smile back 33 percent of the time.
Dr. Palagi said that while some may argue that dolphins simply imitate the mouth expression of others by chance, “it does not explain why the probability of imitating another dolphin’s open mouth in one second is 13 times greater when the receiver actually sees the original expression. .’
The researchers did not record the dolphins’ acoustic signals during play time and say future studies should investigate the possible role of vocalizations and tactile cues during play interactions.
“This rate of mimicry in dolphins is consistent with what has been observed in certain carnivores, such as meerkats and sun bears,” he added.
“The open, relaxed mouth, seen in social carnivores, the play faces of monkeys, and even human laughter, is a universal sign of joy, helping animals (and us) signal fun and avoid conflict.” “.
The researchers did not record the dolphins’ acoustic signals during play time and say future studies should investigate the possible role of vocalizations and tactile cues during play interactions.
“Future research should delve into eye tracking to explore how dolphins view their world and use acoustic cues in their multimodal communication during play,” said corresponding author and zoologist Livio Favaro.
«Dolphins have developed one of the most complex vocal systems in the animal world, but sound can also expose them to predators or spies.
“When dolphins play together, a combination of whistles and visual cues helps them cooperate and reach goals, a particularly useful strategy during social play when they are less on guard against predators.”
The findings were published in the journal iScience.