You’re ever seeing your animals sleep? When their feet and whiskers twitch and yip and mewl? Well, cats and dogs have REM sleep, which probably suggests they have a dream. But have you watched an octopus sleep before? Here we found a video clip of an octopus named Heidi who changes its colors as she dreams.
And while there is no proof of REM sleep in the octopuses till now, they have a type of sleep twitch of their own. Normally octopuses flicker when they sleep. When they are relaxing, neuronal fire in their optics leads the chromatophores or cells that hold pigments to become active. As a result, the pulpits move between colors and designs while snoozing, as though they react to only what they can feel.
Sidarta Ribeiro and his colleagues have established that octopuses are in two distinct sleep stages – active and passive, from the Federal University of Rio Grande do Norte in Natal, Brazil. The scientists videotaped four common octopuses in the laboratory (Octopus Vulgaris) for more than 180 hours of footage over a number of days and nights.
Over a period of more than half the day the animals had slept, says Ribeiro. “They remain in the same position for a long time, the pupils have closed, extremely quiet, very pale – and they respire very quietly regularly,” he said.
Every 30 to 40 minutes, this passive sleep was disrupted by a short active sleep lasting from 1 to 2 minutes. The octopuses revealed changes in color and texture of the body throughout this phase, including the emergence of fine bumps on the skin known as papillae. The eyes and arms of the creatures were also moved. “It’s obviously quite busy,” Ribeiro says.
By showing them a clip of a few crabs, the team has evaluated if the octopuses are actually asleep. “In contrast to your statement, Ribeiro said: ‘If we stimulated the animal with visual or vibrant stimuli, they did not react.’
Heidi is going from a lovely white to a dark deep violet before she becomes a full-blown pattern of camouflage. But Heidi is not the only octopus filmed in sleep that changes colors. The sleeping Caribbean double-point octopus of October 2017 was filmed by Rebecca Otey who interns at the Butterfly Pavilion invertebrate exhibit.
Video Credit & More info: Nature on PBS