Imagine a spider hanging from a silky thread, as if in a still corpse, until its eight legs trembled unexpectedly. While it may sound like a horror movie, it’s actually a nocturnal experience for the jumping spiders (avercha arcuate) who can reach rapid eye movement (REM) sleep, the stage in which most dreams occur, a new study finds.
in the study, published August 8 in the journal Proceedings of the National Academy of Science (opens in new tab)In this study, researchers used cameras to examine the jumping spiders while they were sleeping, observing the arachnids’ eye and body movements throughout the night. The twitching movements the team found when the spiders snoozed were similar to those observed in humans and other mammals. like dogsas well as nonvenomous reptiles and cephalopods during REM sleep.
The discovery came unexpectedly for lead study author Daniela C. Roesler, a behavioral and evolutionary ecologist and postdoctoral fellow at the University of Konstanz in Germany. She originally planned to study the responses of arachnids to 3D-printed models of predatory spiders. But her research quickly turned round when she saw spiders sleeping; At one point, he thought they were dead.
“They were all hanging from the lids of their boxes,” said Rosler. scientific American (opens in new tab), “I didn’t know what happened.”
related: Dead spiders reimagined as creepy ‘necrobots’
With a “cheap night-vision camera” equipped with a magnifying lens attached to duct tape, Rosler focused his lens on one of the women. At first, it just hung there, motionless. But eventually, her legs began to flutter, along with her belly and the silk-producing spinneret. At one point, his legs were bent upwards. The entire performance lasted about a minute and “repeated periodically throughout the night,” Scientific American reported.
“They were just vibrating uncontrollably in a way that actually looked a lot like when dogs or cats are dreaming and they have short REM phases,” Rosler told Scientific American.
For the study, Rosler and his team used an infrared camera to record 34 spiderlings (juvenile spiders). They observed “unmistakable eye-tube movements” that did not occur at other times during the spiders’ sleep cycles. According to the paper, jumping spiders have movable retinal tubes that help redirect their gaze, and in spiderlings, these movements can be seen through their exoskeleton, which remains translucent during their puberty.
Retinal movements of spiders occur at the same time as leg curling and jerking, which are similar to limb movements in other animals experiencing REM sleep, according to a statement (opens in new tab), And while scientists could not easily observe retinal movements in adult jumping spiders, they did document similar leg movements occurring at regular intervals during bouts of sleeping.
Prior to this research, not much was known about the sleep patterns of spiders and other invertebrates, as the study of REM sleep is still largely focused on mammals and birds. However, scientists have already recorded similar action in two other invertebrates: octopus and cuttlefishLive Science previously reported.
While Rosler cautioned that it is too early to say with certainty that jumping spiders are dreaming, the evidence looks promising. To broaden their research, he and his team will need to conduct brain scans to prove that the spiders’ brains are, in fact, in a REM-like state. This is a difficult undertaking, given that these tiny spiders, which are about a quarter-inch (6 millimeters) long, have brains the size of a poppy seed. To record the spiders’ brain activity, scientists would need to insert an electrode into each spider’s brain without crushing it.
Until then, scientists may find themselves dreaming about spider dreams.
“I personally think they are dreaming – like anyone who sees a dog or cat sleeping and kicks their leg will think they are dreaming – but there is no scientifically proven Being able to do it is a whole different story,” Rosler told Harvard Gazette (opens in new tab), “I don’t think we can say they are, and I’m not even sure we’ll ever be able to say it, but the mere fact that we’re thinking about it is already quite surprising.”
Originally published on Live Science.