Do spiders dream?

Spiders, dream or nightmare? - 26th September 2022

New findings imply that like us humans, spiders do sleep and perhaps even dream. An ecologist at the University of Konstanz, Dr Rossler, examined jumping spiders, also called saticids, one of the many species of arachnids. She identified what appears to be a Rapid Eye Movement (REM) sleep cycle leading her to conclude the arachnids are in a dream state.

Having observed the young arachnids, or spiderlings, Dr Rossler noticed a pattern in their eye movement, whereby they experienced rapid retinal movement lasting for about 77 seconds which happened every 20 minutes. Evenmore, their legs curled and uncurled and their abdomen wiggled whilst sleeping, leading the scientist to hypothesise that they're experiencing REM sleep.

Although REM sleep is observed in both humans and animals such as dogs and monkeys, it remains unclear as to why it's practised. Some scientists argue that it supports muscle memory and development for difficult manoeuvres, so in the case of saticids, they could be training their muscles for hunting in their adulthood. Whilst for humans, scientists claim REM aids in stress management.

While arachnophobes experience nightmares over spiders, arachnids themselves might also be suffering a similar ordeal. According to Dr Rossler, during deep sleep, dangling midair, like on a bungee cord, young jumping spiders will, with a sudden jolt, awaken "all the legs get extended at the same time, like aah!"

With limited data on the sleep habits of arachnids, scientists are cautious to confirm whether they dream, even though all the evidence points to them having rest. Hibernating for weeks leading up to months or sleeping with just half their brain at a time, frogs and marine mammals and birds are but a few examples of how sleep manifests in a variety of ways across the animal kingdom.

However, arachnids are far too diminutive to have their brains scanned, hence we may have to settle for never really knowing if they do dream. But given that we prove they do, scientists foresee the possibility of humans developing more empathy and less fear of them. “If they dream, I mean, what can you do? You cannot smush a spider that dreams,” added Dr Rossler.