My Jellyfish Comment
This was posted in 2021 on Hacker News.
Sleep might have helped to maintain the first sleeper’s rudimentary nervous system, but it could just as easily have been for the benefits of its metabolism or digestion. “Before we had a brain, we had a gut,” he said.
I will note that the nervous system of the human gut is so complex that some people speak of it as "a second brain" and there is growing evidence that the gut biome and what we eat significantly impact brain chemistry.
If jellyfish sleep, that suggests sleep may have evolved more than 1 billion years ago
This is sort of off topic.
When me and my adult sons were first homeless, we spent a month in Port Aransas. While we were there, there was a big storm and this storm left a lot of jellyfish stranded on the beach.
My oldest son set out to rescue some of them. He would take a plastic container and plastic utensils and flip them into the container so they couldn't sting him. He would get five or six of them into the container and in his first attempt, he just walked out into the water and dropped them in the water and then he had to get the hell out of the way so they wouldn't wash into his legs and sting his legs.
So he began walking out onto the jetty so he could drop them into the water while standing on a rock. That way he was in no danger of being stung because he wasn't standing in the water he was dropping them into. The other reason he began going out onto the jetty is because they were getting washed back up onto the beach. He felt it wasn't working at all.
And he told me that the jellyfish stranded on the beach all closed themselves up as best they could, as if trying to conserve water while on dry land in hopes of surviving long enough to wash back out to sea.
He reads really fast and has always been interested in science. He knows more about science than I ever will and he told me he had never read anything like that about jellyfish behavior.
Once he dumped them in the water, they "uncurled" and began to pump immediately. So perhaps they were sort of "asleep" or hibernating while on land and once they were in water and safe from this harsh environment that was threatening to be the death of them, they would revive and resume pumping.
He went on a bit about that. He thought it was really exciting and interesting stuff.
I think he saved a few dozen jellyfish over the course of about three days.
Edited for accuracy after fact checking with my son.
In talking with him, he said that at first he thought it was coincidence that they were kind of closed up. But after seeing them all immediately open up and start pumping, he decided "No, I think this is deliberate."
Additional update:
He quit trying to rescue ones that were flat and a different color because he concluded they were dead. Those didn't pump when they went back in the water. The ones that were curled up were still alive.
(Read by my son, edited in accordance with his wishes and signed off by him as an acceptable telling of the story. There should be no further edits after this.)
qrybam on May 19, 2021 [–]
Thank you for sharing this story. Really interesting. If this isn’t part of the literature, hopefully some jellyfish experts will take note!
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2 points by DoreenMichele on May 19, 2021 | parent [–]
I hope so. I did my best to make it as accurate as possible because I don't think it is part of the literature, so I want it to be as useful as possible as a scientific note in case someone does want to pursue this further.
My son told me today that it was a big deal to him precisely because the seemingly intentional nature of the behavior ran completely counter to everything he had read about jellyfish. So all of his reading had "anti prepared" him for what he was seeing. (That's in quotations because that's the actual expression he used today in conversation with me.)