Cuttlefish 'talk' with their arms, study reveals

Summary

Scientists have discovered that cuttlefish use distinct arm movements to communicate with each other, adding another dimension to these already remarkable marine creatures. Researchers from the École Normale Supérieure in Paris and the Italian Institute of Technology have identified specific arm gestures they’ve named “arm wave signs” that appear to serve as a communication system between cuttlefish. The study, published this month in bioRxiv, reveals that these underwater signals can be perceived both visually and through water vibrations – essentially creating a multi-sensory conversation. According to the researchers, this newly discovered behavior involves distinct arm movements that follow specific patterns in two cuttlefish species. These arm wave signs involve deliberate, expressive arm undulations that can last several seconds and be combined in various sequences. The research team, led by Sophie Cohen-Bodénès and Peter Neri, documented these movements over months of observation. They identified four distinct gestures they named “up,” “side,” “roll,” and “crown” signs. Each movement involves different arm positions and undulating motions, often combined with color changes on the cuttlefish’s skin. What makes this discovery particularly intriguing is that the cuttlefish responded differently to these signals depending on their orientation. When shown videos of other cuttlefish performing these arm waves, the animals were significantly more likely to “wave back” when the video was displayed right-side up versus upside-down – similar to how humans perceive faces and other socially relevant displays. But perhaps most surprisingly, the researchers found evidence that these arm motions might be perceived not just visually but also through vibrations in the water. Using specially designed playback experiments, they recorded the mechanical waves produced by these arm movements and played them back to test subjects. The researchers found that these signals work throu...