A common cuttlefish lifts its arms upright (left) and at an angle to match stripes in an aquarium.
The use of two-dimensional patterns allowed the researchers to precisely measure how well the arm positions corresponded to the backdrops—and to rule out the possibility that the animals were basing their configurations on touch, according to study co-author Hanlon.
And because the experiments were done in controlled aquariums, the researchers could be sure the cuttlefish weren't reacting to chemical cues.
Reaching about 17 inches (45 centimeters) long, the common cuttlefish changes its color and skin texture to evade predators, including marine mammals, fish, and seabirds.
"They have an enormous variety of predators, some of which have marvelously good visual capabilities," Hanlon said. "That's why the [cuttlefish] camouflage has to be so good."