Researchers just spotted cunning cuttlefish waving to one another with their tentacles, a previously unobserved behavior that pushes the boundaries of the creature’s intelligence.
Cuttlefish—sometimes referred to as the “chameleons of the sea”—are renowned for their camouflage abilities. In other cephalopods, that color-changing capacity is also used for communication. And like other cephalopods, namely octopuses, cuttlefish are quite intelligent. The cuttlefish’s apparent waving behavior reveals a new aspect of their sophistication, and opens up a new avenue for researchers to investigate their smarts using machine learning. The team’s research is not yet peer-reviewed, and is hosted on the preprint server bioRxiv.
In its research, the team studied four different arm movements in two cuttlefish species, S. officinalis and S. bandensis. The researchers recorded videos of animals signing and played them back to the “cuttlefish participants,” who waved back at the displays. The team also flipped the video in some playbacks, revealing that the cuttlefish were more likely to wave when the video was played upright. The cuttlefish had four different signs, dubbed “up,” “side,” “roll,” and “crown.”
As for the meaning of the arm waves, the jury remains out. The researchers wrote that the signs could be domination signs, as after a cuttlefish waved, other cuttlefish tended to withdraw. But the signals could also be courtship displays—though the signs were also made by juvenile cuttlefish that were not yet sexually mature. Other possibilities remain: The signs could be aversive displays, made in defensive contexts, or exhibit internal states such as mood in the animals. “The most plausible interpretation is that these signs are symbolic and can encrypt a variety of possible meanings depending on the associated behavioral contexts,” the team wrote.
But the arm waves themselves are not the whole story.
“In addition to their visually striking display, arm wave signs produce mechanical waves in the water, prompting us to explore the possibility that they may also be perceived via mechanoreception,” the team wrote. In other words, even when the animals could not see one another underwater, they could feel the vibrational waves produced by the arm movements of the other participants.
“Using playback experiments similar to those adopted in vision, we obtained preliminary evidence to support this hypothesis, indicating that arm wave signs may represent multimodal signals involving vision and mechanoreception,” the group added.
Cuttlefish are bright; previous research indicated the animals are capable of waiting for a reward when there’s a promise of a bigger payout. The animals are able to plan for the future, which previously was thought to be a behavior only exhibited in mammals and birds.
The researchers, including first author Sophie Cohen-Bodénès from Perceptual Systems Laboratory at the École Normale Supérieure (ENS) in France, added that machine learning algorithms could be applied to similar data to better understand how the animals dished out different arm signals depending on the stimuli. Similar work has been done with sperm whale click data with stunning success—researchers recently managed to identify specific patterns of speech in the animals’ communiques, and roughly assemble their “alphabet.”
Cuttlefish’s intelligence, reasoning, and behavior remains enigmatic, but the new research indicates that the animals have plenty more secrets to decipher.