The blare of human noise causes birds to pipe down and frogs to breed less frequently. Now, scientists have found a humanmade sound that has a far more colorful effect: The boom of a ship’s engine makes common cuttlefish (Sepia officinalis) change the complex swirls of skin hues, stripes, and spots that they use for camouflage and communication. Like other cephalopods such as octopus and squid, cuttlefish rely on visual and tactile signals to communicate; there’s been little evidence so far to suggest they perceive—or respond to—sound. But when researchers placed a loudspeaker near cuttlefish tanks and played the sound of an underwater engine, the animals swam more and changed colors more often. They also raised their first pair of arms, which are used to sense water movements, more frequently, the team reports in this month’s issue of The American Naturalist. The sounds of crashing surf had no effect, providing the first evidence that engine noise may stress the animals out. The fast color changes could hinder camouflage when ships are near, increasing the animals’ chances of being spotted by predators. Cuttlefish distracted by human clamor in the sea may also find it difficult to woo mates or sense the movements of potential prey, the researchers suggest. Because cuttlefish are important both as predators and prey in marine ecosystems, the changes might also ripple into wider impacts on life underwater.