Octopuses have an extremely effective means of camouflaging when it comes to escaping predators or, for stalking their prey. Colors and patterns of their bodies change according to the requirements of different situations. But this system is also activated when these animals are sleeping. Although marine biologists do not yet fully understand the process, they hypothesize that these color changes may be related to cephalopod dreams.
Sleeping octopuses can change color. While they are resting, certain neurons that fire in their optic lobes cause their chromatophores, cells containing pigments, to activate. As a result, octopuses change color and pattern while they sleep, as if they’re reacting to a dreamlike situation.
This spectacular effect can be seen in a new video, shot for the documentary Octopus: Making Contact on Nature on PBS. In this part of the documentary, marine biologist David Scheel of Alaska Pacific University explains the change in color of a sleeping octopus named Heidi. These color and pattern changes seem to correspond to real world behaviors. Scheel narates comparing them to possible real encounters / stimuli.
Although the mechanisms of dreaming are not yet well known, scientists believe it has something to do with how the brain processes and stores memories. If so, it would make sense for many animals to dream, even cephalopods, whose intelligence is quite different from that of mammals.
Although REM sleep was not recorded in octopuses, another cephalopod showed something similar. A 2012 study found that cuttlefish Sepia officinalis “display a quiescent state with rapid eye movements, changes in body colouration and twitching of the arms, that is possibly analogous to REM sleep.“
Heidi isn’t the only octopus to have changed color while sleeping. In October 2017, Rebecca Otey, who was doing an internship at The Butterfly Pavilion Invertebrate Zoo, filmed a sleeping Caribbean octopus ( Octopus hummelincki ) and posted the video on YouTube:
We know that octopuses use their amazing camouflage ability to change colors. One might be tempted to think that involuntary color spasms would spoil this camouflage, but fortunately, they take precautions before sleeping by building hidden dens, in their natural environment at least, where they retreat to take a nap.
