The next time you see a spider hanging upside down in your apartment, it may be napping a bit like humans.
Behavioral ecologist Daniela Rößler made this accidental discovery when she first saw jumping spiders dangling in her lab in 2020. Rößler and her research team recently published their findings in the journal Proceedings of the National Academy of Sciences.
Rößler, a researcher at the University of Konstanz in Germany, originally set out to study predator-prey interactions in spiders. She used baby spiders for her experiment and filmed the animals opportunistically at night with an infrared camera.
The spiders exhibited something called rapid eye movements (REM), a behavior that we and many animals often experience while sleeping. During REM, activities in the body, such as heart rate escalateswhile the eyes remain closed and move rapidly.
A large spider will spread in the US No, it will not ‘sky jump’.
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While watching the spiders, the research team also observed that the animals occasionally trembled with their limbs, another classic REM behavior. Together, these findings suggest that spiders could have a dreamy, sleep-like state. There is already evidence that fruit flies sleep. But this is the first time the REM pattern has been documented in a jumping spider, Rößler said.
But what seems like sleep to us may or may not be sleep in spiders. While the research team’s findings strongly suggest that spiders sleep, the evidence isn’t certain yet, Rößler noted.
“If we really want to understand the function of sleep, we need to look at it where it happens.”
As an extension of this research, Rößler plans to conduct sleep studies in a field atmosphere rather than catching and studying spiders in an artificial laboratory setting. “If we really want to understand the function of sleep, we have to look at it where it happens,” she explained.
Nevertheless, the laboratory environment still yielded convincing results. It is a well done study that documented twitching in spiders, said Mark Blumberg, a professor at the University of Iowa who studies twitching and REM sleep in rats and human infants. Blumberg was not part of this newly published study.
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Blumberg acknowledged that it is difficult to study sleep in animals because animals experience sleep differently than we do. “I agree with a lot of the study. I don’t agree with everything,” Blumberg told Mashable. The nervous system of a spider or fly is very different from that of a rat or a human, which is why we can’t expect all characteristics of sleep to be the same in spiders, he stressed.
Rößler’s study addressed the possibility that spiders dream during sleep, thanks to the eye movement patterns the arachnids experienced in REM sleep. During REM sleep, vivid hallucinogenic dreams occur in humans. The new study raises the potential of studying the existence of visual dreams in spiders. But according to Blumberg, the dream connection is too uncertain and unconvincing.
“I think we’re going to find great things in the coming years.”
Dreaming in spiders also remains a big question for Rößler. She hopes to understand better if people can even fathom how a spider can dream, if they dream at all. “We always have a human bias to understand the world,” she said.
There is still much to discover about sleep in animals. But perhaps more insights will emerge. “I think we will find great things in the coming years,” Rößler said.