Almost all cephalopods—the class of ocean dwellers that includes octopuses, cuttlefish, and squids—have an incredible ability not just to change the color and patterns on their skin, but also to transform their body’s shape and texture.

Thanks to these tricks, cephalopods can radically change their appearance faster than the blink of an eye, the swiftest known change in the animal kingdom.

“They’re the best at it of anything that we know,” says Michael Vecchione, the curator of Cephalopoda at the Smithsonian National Museum of Natural History. This is especially surprising since most cephalopods are color-blind, so we have yet to understand how they can fully perceive what to copy in the first place.

“It has to have been evolutionarily important for them to evolve [the ability to change color and texture] and to evolve so many different versions of it,” says Vecchione. Indeed, studies suggest that each cephalopod species has evolved up to 30 different ranges of patterns to hide in plain sight.

This group of soft-bodied mollusks have skin covered in millions of pixel-like cells called chromatophores: pigment-filled sacs each surrounded by their own small muscle fiber. These muscles can stretch the chromatophore to flood with color or contract and shrink to a dot, creating varied, complex patterns. Octopuses and cuttlefish are also covered in small bumps, flaps, branches, and ridges called papillae, which can be ruffled upwards or smoothed out to create different skin textures too.

(Stream Secrets of the Octopuses now on Disney+ and Hulu)

The common day octopus (Octopus cyanea) can become almost see-through beige and white on flat sandy surfaces; dark, mottled, and rugged on bumpy rocks; and flashes orange, red, and brown spikes along corals. Cuttlefish sometimes clump up, shrivel, and hide their arms to look like a tuft of algae, and baby giant cuttlefish (Sepia apama) hiding among seaweeds have been recorded sending waves of shaded dark brownish-green pigments across their body to copy the motion of swaying seaweed.

Common octopus (Octopus vulgaris) hunts through a low bed of kelp on the ocean floor near Catalina Island, California.
PHOTOGRAPH BY RUSSELL LAMAN

While these shapeshifting skills certainly come in handy for inconspicuous disguises, there are many other reasons octopuses and other cephalopods change their skin—and they may surprise you.

To intimidate predators

Sometimes cephalopods need to do the opposite of blending in to escape a predator.

If they’ve been caught while in camouflage, many octopus species can turn their bodies dark and cloudy, darken their eyes, stretch out their body and arms to look bigger and stand taller. Cuttlefish even create eye-like shapes on their mantle — their sack-shaped body — back to stare down their predator.

Predators learn to associate the highly venomous blue-ringed octopuses with the gaudy rings of indigo they flash across their yellow skin to alert predators they’re not to be messed with.

(8 fascinating facts about octopuses—from their supersmarts to their favorite foods.)

Meanwhile, the less-dangerous mimic octopuses (Thaumoctopus mimicus) impersonate all sorts of animals that are more threatening or venomous than they are. Among many other disguises, they can spread out their arms and display white and brown stripes to look like the sharp-spined, highly venomous lionfish.

A Broadclub Cuttlefish (Sepia latimanus) displays sandy colors in the Lembeh Strait of Indonesia.

To trick and hypnotize their prey

Mimicking other animals also helps cephalopods to appear less threatening and get close to their prey. Pharaoh cuttlefish (Sepia pharaonis) have been seen using their color, texture, and movement to appear as docile hermit crabs to their prey, the tropical damselfish. Caribbean reef squid (Sepioteuthis sepioide) swim in reverse and wave their arms like fins to look like herbivorous parrotfish, also to get close to their prey.

Cephalopods can also send stripes, circles, and patterns of color across their body as if to bamboozle their prey before striking. Martin How, an ecology of vision researcher at the University of Bristol, studies how Broadclub cuttlefish (Sepia latimanus) ripple dramatic dark rings of color from their head to their arms as they get closer to their prey. “It’s almost like a magician trying to mesmerize, or hypnotize their audience,” he says, theorizing this helps the cuttlefish is disguise its approach, looking farther than it is, to catch the prey off guard.