Research shows

Scientists have found that cuttlefish use different arm movements to communicate with each other, adding another dimension to these already outstanding marine life.

Researchers from the École Normale Supérieure in Paris and the Italian Institute of Technology have identified specific arm gestures they call “Arm Wave Signs” that appear to be a communication system between cuttlefish. The study published this month in Biorxiv shows that these underwater signals can be perceived visually and water vibrations—essentially creating multisensory conversations.

According to the researchers, this newly discovered behavior involves different arm movements that follow specific patterns of the two cuttlefish species. These arm wave symbols involve deliberate, expressive arm undulations that can last for several seconds and combine in various sequences.

The team of research led by Sophie Cohen-Bodénès and Peter Neri documented the movements over several months of observation. They identified four different gestures that they named “UP”, “Side” and “Crown” logos. Each movement involves different arm positions and ups and downs, often combined with color changes on cuttlefish skin.

What makes this finding particularly interesting is that cuttlefish respond differently to these signals, depending on their orientation. When other Moran Powder videos are displayed performing these arm waves, animals are more likely to “wave” when the right side of the video is displayed with the inverted situation, similar to the way humans display faces and other socially related displays.

But perhaps most surprisingly, the researchers found evidence that these arm movements are perceived not only visually, but also by vibrations in the water. They used specially designed playback experiments to record mechanical waves generated by these arm movements and play them back to the test subject.

The researchers found that these signals work through multiple sensory channels. By using specialized playback experiments, they demonstrated that cuttlefish can perceive these communications visually and in water motion detection.

Cuttlefish respond faster to the original recordings than versions played backwards or competed for, suggesting that they can detect meaningful information in these water sports.

This dual-channel communication system may utilize the transverse lines and statocysts of cuttlefish to detect water motion and low-frequency vibration sensory organs. These findings suggest similarities between cephalopod communication and audiovisual communication seen in vertebrates despite independent development.

The team pointed to fascinating evolutionary similarities, suggesting that just like the cephalopods’ independently evolved camera-like eyes resemble vertebrates, their sensory system used to detect water movements may have evolved to have communication functions similar to vertebrate hearing.

The exact meaning behind these arm signs is not yet clear. Researchers observed them in various situations—in mating, hunting, defense conditions, sometimes spontaneous. This suggests that these signs may have multiple purposes depending on the situation.

The discovery opens new avenues to understand the communication of marine invertebrates and increases our appreciation of cephalopod intelligence. These surprisingly complex “dialogues” occur under the waves, highlighting how much we still need to know about communication in the animal kingdom.

Going forward, the team hopes to explore how this discovery might provide insights into exchanges between distinct animal species and potentially open up new avenues to understand the diverse organisms’ interactions with the environment.

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