Anyone who’s owned a dog (or been owned by a dog) and has watched their dog sleep, has probably seen their dog dreaming. Barking softly, legs twitching, eyes moving under closed lips, maybe the tail wagging.
In a human being, we’d call this “REM” sleep, and it typically happens when we’re experiencing a dream.
Dogs are noticeably more physically demonstrative during the dream state, in my humble opinion, than humans. When I was married to my ex-wife Darlene, we sometimes slept in the same bed, and I can vouch for the fact that I never heard her bark softly while dreaming. Mumbling, maybe.
Cats are occasionally known to display similar signs of ‘dreaming’, although they tend to be a lot more private about it.
Scientists have identified indications of REM sleep in octopuses and insects, and many species of mammals and birds.
Apparently, spiders are also prone to REM sleep. Jumping spiders, in particular.
If you’ve ever seen a close-up photo of a jumping spider, you might consider them “cute”… with their little bug eyes and whiskers and furry legs. According to a behavioral ecologist at the University of Konstanz in Germany named Daniela Roessler, jumping spiders are surprisingly intelligent, in addition to having a well-developed nocturnal dream life. Or so it seems.
Jumping spiders “tailor tailor their hunting strategies to the species of their prey… and they have elaborate mating dances…” according to an August 2022 article on NPR.com
Dr. Roessler recently led a study that found jumping spiders experience something like rapid eye movement (REM) sleep when they rest at night. Her team filmed jumping spiders overnight and observed behaviors that mirror REM sleep in other species.
Typically, jumping spider hang upside down from a strand of web, while they are ‘sleeping’.
“All the legs would curl into the body and they would twitch… We also detected quite significant and very obvious eye movements.”
I feel a little bit embarrassed, reading this. On behalf of the spiders, I mean. I myself would hate to be filmed while I was sleeping. It’s bad enough to have your wife watching you sleep, but how much worse to have a team of German scientists reviewing your twitching legs and “obvious eye movements” on film?
From what little I’ve learned about jumping spiders, and their intelligence and mating rituals, I wonder if they don’t also have feelings of embarrassment, with all this filming taking place. But since I don’t know for sure, I will be embarrassed for them.
Dr. Roessler is careful to admit that we don’t actually know if jumping spiders “sleep”. They have no eyelids, so they can’t close their eyes like a dog or cat. And if we don’t know if they sleep, then we’re only guessing that they also ‘dream’.
“I mean, it’s beautiful to think about it that way,” says Dr. Roessler, “that these spiders hang there and they have a visual scene of catching a fly or trying to get a mate. It’s quite cute, but probably is going to be very different.”
I would hope it’s very different. Especially the part about catching a fly. I don’t always remember my dreams, but I’m fairly certain I have never dreamed about catching a fly.
Now, trying to get a mate? I may have had that dream.