Octopuses are incredibly clever beings that have been known to escape the confines of their aquariums, play hide-and-seek, solve puzzles, and even use their arms as tools. Just like humans, octopuses act more social, engaged, and interested in their surroundings given MDMA. Their uniquely evolved body has also led some to speculate that the cephalopods originally came from outer space.
Now, it appears that the eight-limbed mollusks dream in their sleep.
David Scheel, a professor of marine biology at Alaska Pacific University in Anchorage, has been raising a day octopus named Heidi in a tank in his living room. She recognizes her human caretakers and loves to play with Scheel’s daughter Laurel by chasing a ball on a string. But in a new video captured by the daddy-daughter duo, Heidi shows signs of potential dreaming in what Scheel calls a “dramatic moment.”
However, Scheel is quick to note that he is neither a sleep biologist nor an expert in such behaviors. Because there is no associated peer-reviewed study, he says he can speak about sleep and octopuses simply from a "passing familiarity".
In the video, Heidi appears to be sleeping with her legs wrapped neatly under her mantle. Gradually, her coloring changes, flashing between white and orange to a deep rusty red before pulsing stark white and camouflaged hues.
“You could almost just narrate the body changes and narrate the dream," said Scheel in the video as Heidi turns all dark, a tactic that octopuses do just before leaving the ocean's bottom. According to Scheel, Heidi’s “unusual” behavior may mean there is more to octopuses than meets the human eye.
“Sleep can be recognized behaviorally, and studies have found that both octopuses and their relatives [the] cuttlefish have behaviors that satisfy the definition of sleep: they become quiescent and less responsive to disturbance but can be roused. After a period of sleep deprivation, they sleep longer to catch up. And their brains are active during these sleep behaviors,” Scheel told IFLScience in an interview, adding that cuttlefish also display a “similar sleep-like state with rapid eye movements and changes in body patterns with twitching of the arms” that could be analogous to REM sleep, the state in which humans dream.
During rest times, octopuses will often display a pale smooth skin pattern with limply held arms. However, some will start twitching their suckers or arms and change their skin's pattern display.
“It should remind us that our own experiences and challenges are not that different from those faced by others, even when we have very distinct lifestyles,” said Scheel.
However, other possibilities for Heidi's nighttime color-changing can't be ruled out. Sleep helps biology stay active and healthy, ensuring that everything is running properly. (Think men and erections, which doesn't necessarily mean they are dreaming of sex.) It may also be that at a certain point during the octopus' sleep cycle, she has less control over her color-changing cells.
Day octopuses (Octopus cyanea) are endemic to the waters of the Indo-Pacific and Hawaii. Reaching up to 80 centimeters (31.5 inches), the Monterey Bay Aquarium describes the cephalopod as “one of the most athletic and active species” capable of huffing and puffing and blowing water. As Scheel’s video shows, the day octopus can even change its skin into lumpy bumps and ridges to mirror nearby coral, rocks, and algae.
Scheel’s video is set to air on the PBS special Nature – Octopus: Making Contact on October 2, 2019.