Cuttlefish Look Like Squid—and Like Crabs, and Like Algae, and Like Rocks

A new study examines the muscles, nerves, and chemicals that enable cuttlefish—animals related to squid—to change their skin texture, mimicking another animal or their surroundings.

When little bumps all over their skin, called papillae, stick out, two kinds of muscles are involved in the display. One kind, striated muscles—like skeletal muscles, such as your biceps—help the cuttlefish raise the spiny nubs fast. Another kind, which are similar to the smooth muscles in your gut, seem to allow the bumps to stay up for as long as an hour without using much energy.

Gonzales-Bellido and her collaborators also discovered that the a secondary nerve bundle, not the brain, controls the muscles, which hints at a deep evolutionary connection to a similar neural circuit in squid.