Dolphins are one of the most cheerful and sociable animals on the planet, but not much is known about how they communicate during games and other casual interactions. New research on captive bottlenose dolphins (Tursiops cut off) indicates the use of an “open mouth” facial expression, similar to a smile, to communicate during social play. This expression is most consistently used when the dolphin is within sight of a playmate, and some dolphins respond with a similar expression. For more information on the survey results, please visit The study was published Oct. 2 in the journal Cell Press iscience.
For dolphins, Play includes: Acrobatics, surfing, playing with objects, chasing, and pretend fighting. Although these activities may seem aggressive to humans, they generally are not. Other mammals, including primates, use facial expressions to convey playfulness, but it was not clear whether marine mammals also use facial expressions to do this.
[Related: Male dolphins form alliances to help each other pick up mates.]
“I spent years studying the play of different species, and Livio [Favaro] I also wanted to start researching dolphin play. ” Elisabetta Palagisaid study co-author and comparative behaviorist at the University of Pisa. popular science.
in studyparagi, Favaro – Marine biologist at the University of Turin– Video recording of 22 bottlenose dolphins from four social groups. They filmed the dolphins playing in pairs, alone, and with human trainers.
“After recording the first video, we noticed that the dolphins emitted long displays with their mouths open while playing, but we did not see similar behavior in other situations,” Palagi said. says Mr. “Opening the mouth is not a bite. During the open mouth expression, the subject never attempts to bite the playmate.”
The researchers believe that this gesture likely evolved from the act of biting, and that the act itself, when broken down, includes only the intention to bite without contact. This relaxed open mouth is seen by carnivores as a sign that humans are having fun, including when humans are smiling.
The dolphins in the study almost always had this open-mouthed expression when a playmate came into view. Credit: iScience Maglieri et al.
Video: The dolphins in the study almost always had this open-mouthed expression when a playmate came into view. Credit: iScience Maglieri et al.
The research team observed that open-mouthed facial expressions mainly include: Used when playing with other dolphinsbut not when they are playing with humans or playing solo. Only one open-mouth event was recorded when the dolphins were playing alone, but 1,288 open-mouth events were recorded during social play sessions. total 92 percent One of these expressions occurred during a dolphin-dolphin play session. Additionally, children were more likely to make this open-mouthed expression when their playmate’s face was in their field of vision.89% of recorded open mouth facial expressions.
Importantly, when this “smile” was recognized, the playmate smiled back. 33% chance. Although it could be argued that the dolphins are just copying this expression by chance, Palagi said, if the recipient physically saw the original expression, within a second they would have been able to copy another dolphin’s open expression. It doesn’t explain why people are about 13 times more likely to imitate a mouth.
Playmates imitating the open-mouth facial expression were observed 33% of the time during the study period. Credit: iScience Maglieri et al.
video: Playmates imitating the open-mouth facial expression were observed 33% of the time during the study period. Credit: iScience Maglieri et al.
“This rate of mimicry in dolphins is consistent with what has been observed in certain carnivores, such as meerkats and sun bears.” Palagi said in a statement accompanying the paper’s publication..
The team did not record any dolphin acoustic signals during playtime. Future research could investigate the possibility that vocalizations and tactile signals also have a purpose during playful interactions.
[Related: Young dolphins mimic sex as part of play.]
“Future research should delve into eye tracking to investigate how dolphins perceive the world and use acoustic signals for multimodal communication during play.” Favaro said in a statement:. “Dolphins have developed the most complex vocal system in the animal kingdom, but sound can also expose them to predators and eavesdroppers. When dolphins play together, they combine whistles with visual cues. , which helps dolphins work together to achieve a goal, a strategy that is especially useful during social play when there is less fear of predators.
