Jumping spiders rapidly move their eyes and twitch during rest, suggesting they have visual dreams, never before observed in arachnids.
An international team of researchers studied the retinal movements of baby jumping spiders as they slept and found they coincided with body movements associated with REM sleep in other animals.
“This report provides direct evidence for a REM sleep-like state in a terrestrial invertebrate – an arthropod – with clear parallels to REM sleep in terrestrial vertebrates,” the authors say. “The combination of periodic limb twitches and eye movements during this sleep-like state, as well as the increase of duration of REM sleep–like bouts, meets core behavioural criteria of REM sleep observed in vertebrates, including humans.
“Eye movement patterns during REM sleep have been hypothesized to be directly linked to the visual scene experienced while dreaming – begging the deeper question of whether jumping spiders may be experiencing visual dreams,” they add.