- Spiders showed patterns that looked like sleep cycles, suggesting they snooze like humans.
Do spiders even sleep? Does everyone remember hearing that people swallow like 7 spiders a year or something like that? Or just me?
In a study by Daniela Roessler and her colleagues, baby jumping spiders were watched by cameras at night. Footage caught showed sleep cycle-like patterns. During this time, the spiders’ legs twitched and parts of their eyes flickered.
The group described the pattern as a “REM sleep-like state.” For us humans, REM or rapid eye movement, is an active phase of sleep. It’s when parts of the brain light up with activity and is closely linked with dreaming.
Some birds, mammals, and other animals have shown experiencing REM sleep. However, creatures like jumping spiders hadn’t gotten as much attention, so it wasn’t known if they got the same kind of sleep, Roessler, evolutionary biologist at the University of Konstanz in Germany.
Roessler, along with her team, dug into sleep after discovering that the spiders were hanging from threads of silk in their lab containers at night. She recently scooped up the jumping spiders to study.
The species is a furry brown body with four pairs of big eyes. “It was just the most unusual thing I’ve ever seen,” Roessler said of the suspended spiders.
The movements of the spiders overnight looked a lot like REM in other species, like dogs or cats twitching in their sleep. The movements happens in regular cycles, similar to what we see in sleep patterns when humans sleep.
Other species similar to spiders don’t have moveable eyes, which makes it hard to compare their sleep cycles, explained study co-author Paul Shamble, an evolutionary biologist at Harvard University.
These jumping spiders are the predators that move their retinas around to change their gaze while hinting. And the baby spiders have a see-through outer layer allowing a clear window into their bodies.
“Sometimes as a biologist, you just get really, really lucky,” Shamble said.
Research is still needed to determine whether the spiders are actually thinking while in these resting states, including if they respond more slowly, or not at all, and what triggers might normally set them off.
There is some doubt among researchers. “There may be animals that have activity in quiet states,” said Siegel, of the UCLA Center for Sleep Research. “But are they REM sleep? It’s hard to imagine that they could be the same thing.”
Even so, Barrett Klein, an entomologist at the University of Wisconsin-La Crosse who was also not invo2427lved with the study, said it was exciting to find REM-like signs in such a distant relative.
REM sleep is “still very much a black box,” Klein said. There are still many questions regarding REM sleep and what possible purpose they may serve for the species.