Octopuses, one of the most astonishing invertebrates known for their impressive intelligence, have been seen twitching in technicolor, with researchers questioning whether octopuses could dream?
As it wraps its eight legs snug around itself, its pupils narrow, breathing evenly, and its body shifting to a uniformed gray.
Suddenly it changes color, shifting from burnt orange to a rusty red. The octopus' muscles and sucker pads twitch as if the invertebrate is experiencing vivid dreams.
In 2015, an octopus named Heidi went viral for a video where it apparently changes colors as it seemed to sleep soundly.
Could Octopus Dream?
Brazilian researchers explain that the octopus' shifts in color, movement, and behavior are evidence of an apparent sleep cycle in cephalopods-- with the 8-legged invertebrate switching from active to quiet sleep equal to the humans deep sleep and REM sleep.
A study published in the journal iScience, entitled "Cyclic alternation of quiet and active sleep states in the octopus" shows that sleep may have evolved similarly in different creatures, suggesting that octopuses might be experiencing a similar phenomenon to dreaming.
Sidarta Ribeiro and Sylvia Medeiros, lead authors of the study from the Brain Institute of the Federal University of Rio Grande do Norte said in an email that it's virtually impossible to definitively say whether octopuses can dream or not because they can't tell us otherwise.
However, research shows that during the invertebrates 'Active sleep' the octopus experiences analogous to REM sleep, a state where humans dream the most.
Scientists previously believed that different sleep states could only be experienced by mammalian and avian species.
On the other hand, recent studies show that other species like reptiles and cuttlefish--a member of the cephalopod family relative to the octopus--show non-REM and REM-like sleep behavior.
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Studying Octopuses Sleep Behavior
To understand octopuses' sleep behavior, researchers recorded 4 members of the octopus insularis species studying the creatures' behavior over a 50-day period.
During laboratory research, the octopuses were seen to be sensitive to weak stimuli when alert, however, in both sleep states the invertebrates needed strong visual or tactile stimulus to evoke responses.
Octopuses are known for changing skin color for communication and camouflage, but during sleep, environmental stimuli are no longer a contributing factor to the changes.
Researchers inferred that the octopuses' technicolor twitches during sleep result from independent brain activity.
Despite the cephalopods' brain structure differing from mammalian brains, they share some functions. Octopus has been known to have specialized learning abilities where they could solve problems and other sophisticated cognitive abilities.
The team found that octopuses experience active sleep after a long episode of quiet sleep, equivalent to roughly 6 minutes.
Authors of the study say that if octopuses were in fact dreaming, they are unlikely to experience complex symbolic plots like humans. 'Active sleep' in the invertebrates is short in duration typically ranging from a few seconds to a minute.
Researchers theorize that if dreaming in octopuses is possible, they would see dreams similar to short videoclips or gifs.
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