Cuttlefish Communicate Through Complex Arm Gestures, Researchers Discover

If you happen to see a friend across the street, you might wave to get their attention. Cuttlefish, it turns out, have a similar instinct, and they use a variety of arm gestures to communicate, as detailed in a recent bioRxiv preprint. Researchers focused on two species of cuttlefish: the common cuttlefish (Sepia officinalis) and the dwarf cuttlefish (S. bandensis). During their observations, they noticed several distinctive behaviors that seemed to serve as signals. For instance, the cuttlefish would sometimes raise a pair of arms in a gesture reminiscent of a wave, which the researchers termed the "up" sign. They also observed the creatures sweeping all their arms to one side, folding them under their heads, and touching just the tips of their arms together, labeling these actions as "side," "roll," and "crown," respectively. To test whether these gestures were indeed forms of communication, the researchers recorded videos of the cuttlefish displaying these signs and showed the footage to other individuals of the same species. When exposed to the video recordings, the cuttlefish typically responded by reproducing the gestures. However, the responses weren’t always exact replicas, suggesting that the cuttlefish weren’t merely mimicking what they saw but were engaged in a more nuanced interaction. Further experiments involved using a hydrophone to capture the pressure waves generated by each gesture. The researchers then played back these sounds to the cuttlefish without showing them any visual cues. Surprisingly, the animals still responded by signing, especially near the hydrophone. This indicated that the gestures could be a form of nonvisual communication, likely mediated through the sounds they produce. While these findings are intriguing, the researchers caution that before labeling these movements as a true sign language, they need to demonstrate that each gesture has a distinct and consistent meaning. To achieve this, the team is developing artificial intelligence tools to analyze the cuttlefish's behavior more deeply. They are also exploring whether the signs are used to communicate with prey or other species, in addition to fellow cuttlefish. These observations highlight the sophisticated communication abilities of cuttlefish and open new avenues for studying the cognitive and social behaviors of these fascinating marine creatures.