Octopus That Changes Color While Sleeping Might Be Dreaming, Scientist Says: 'This Really Is Fascinating'

PBS has released a fascinating video clip from an upcoming documentary which shows an octopus changing color multiple times in its sleep.

The sequence features in Octopus: Making Contact, which will premiere on October 2. The film focuses on marine biologist David Scheel from Alaska Pacific University as he raises and studies an octopus, known as "Heidi" in his home.

Over the course of the filming process, Scheel makes "remarkable discoveries" about the animal's extraordinary intelligence, personality and skills, according to the producers.

The clip released by PBS begins with shots of Heidi in her tank, with Scheel narrating.

"Last night, I witnessed something I've never seen recorded before," he says.

We are then shown images of Heidi sleeping upside-down while her skin rapidly switches between different colors. Scheel suggests the possibility that the animal is dreaming—although this has not been confirmed by research—while going on to speculate about what it is she could be thinking about.

"If she is dreaming, this is a dramatic moment," Scheel said. "You could almost narrate the body changes and narrate the dream. She sees a crab and her color starts to change a little bit, then she turns all dark, octopuses will do that when they leave the bottom [of the ocean.] This is a camoflage, like she's just subdued a crab and she's just going to sit there and eat it, and she doesn't want anyone to notice her."

During resting times, octopuses often display a pale smooth skin pattern with their arms held limply.

"I have seen this commonly," Scheel told Newsweek. "However, during some periods they may show some sucker and arm twitching (random movements) and changes in skin pattern display."

Some of this is visible in the clip, but the scientist notes that he hadn't ever sat and observed the phenomenon before.

"It's a very unusual behavior to see the color come and go on her mantle like that, just to be able to see all the different color patterns flashing one after the other, you don't normally see that when an animal's sleeping," he said. "This really is fascinating."

The mantle is a significant part of the octopus anatomy which is located behind the head and directly opposite the arms. This large, bulbous structure contains all of the animal's organs.

Octopuses—like their fellow cephalopods squids and cuttlefishes—are among the few animals on the planet that can rapidly change the color of their skin, to match their surroundings or make them stand out, according to the Smithsonian Museum of Natural History.

This ability is the result of color-changing cells just below the surface of the skin, known as chromatophores. Octopuses can even change the texture of their skin—say, to match rocks—by altering the size of small bumps on their skin called papillae.

Despite the color-changing behavior in the video, we simply don't know whether octopuses dream. But intriguingly, a group of scientists found in 2012 that their cuttlefish relatives go through a phase of rest that is remarkably similar to rapid eye movement (REM) sleep, which is often linked to dreaming in humans.

This finding did not prove that cuttlefish dream either, but it does leave open the possibility, according to the researchers.