The researchers put several specimens in a tank in their lab to observe them as they interacted with one another. They also videotaped several specimens as they moved their arms and played the videos back to the cuttlefish to see how they would react. They found four waving patterns that appeared to be consistent—up, side, roll, and crown.

They also found that the cuttlefish responded by waving back when viewing cuttlefish on video waving with any of the four patterns. When the researchers played the videos upside down, such responses were greatly muted.

The researchers also noted that the waving patterns used by the cuttlefish generated vibrational waves, which may also allow the cuttlefish to communicate messages when they can’t see each other.