Joyful communication: Dolphins use open mouth expressions while playing

Scientists found that bottlenose dolphins (Tursiops truncatus) use the open mouth expression as a means of communication while engaging in play, highlighting its significance in social interactions akin to human smiling.

Dolphins are often observed performing underwater acrobatics, playing with objects, and engaging in chase games. However, this new research reveals that this facial expression is particularly important for communication among dolphins during play.

STUDY INSIGHTS

Dr. Elisabetta Palagi, an evolutionary biologist from the University of Pisa, noted that dolphins signal enjoyment to one another through the open mouth expression during their social play. The study indicated that this expression strengthens social interactions and helps avoid conflicts.

This expression, observed in humans, monkeys, and some social carnivores, may have played a significant role in the evolution of social communication.

RESEARCH DETAILS

Researchers examined 22 captive dolphins through 80 hours of video recordings, identifying the open mouth expression during 837 play sessions. This expression was particularly prevalent, appearing 92% of the time during dolphin-to-dolphin play.

The research team noted that the expression is used more frequently when visible to other dolphins. Dr. Palagi emphasized, "Dolphins do not merely mimic each other; this expression serves as a conscious tool for social communication."

The study's findings were published in the journal iScience.