7 ms·
Starfish bodies aren’t bodies at all, study finds
- Qem 3y agoSo starfishes are like guild navigators from Dune, that took so much mélange spice until they were reduced to giant brains with limbs, but in real life. Amazing!
- brnt 3y agoI had to think of that The Thing scene; yours is much less disturbing.
- mcpackieh 3y agoTrying to say they have heads at all seems like trying to cram a square peg into a round hole. It's interesting that their bodies evolved from what was once the head of their ancestors, but in what meaningful sense is it presently a head? It's more like "head" is a discrete label created by and for the convenience of humans, and being a discrete label it doesn't really map cleanly to real world data in all cases. It's like saying humans have four legs, or dogs have two arms, because the front/top two limbs are related to each other. The labels of 'legs' and 'arms' aren't really meant to be used in this way, regardless of what evolutionary history says.
- radarsat1 3y agoI agreed with you until I read the article. It actually makes some really interesting observations about the comparison it's making regarding the typical definition of "head" and how body parts in general relate to gene expression patterns. The images in the article are really cool.
- mcpackieh 3y agoThe article convinced me that starfish bodies developed from heads, just as I'm convinced that primate arms developed from legs, but it didn't convince me that it's appropriate to call the modern forms of these things heads or legs.
- svnt 3y agoIf your education includes substantial aspects of evolutionary developmental biology and genetics, then you have important mental models with which you can work with an organism. If you discover that the whole organism is effectively developmentally a head, then it is extremely appropriate to refer to it essentially as a head. If you instead relate to the organism in its present form in some more mundane ways then it might not seem that way. Analogies are failing me, but perhaps it would be like realizing an entire government basically spawned out of the centering concept of religious freedom. The structure of it then makes a lot more sense.
- nyanpasu64 3y agoI'd say that whale flippers are homologous to legs/feet, but aren't legs/feet. This article says that starfish are homologous to heads, but I'm not sure whether I'd consider their bodies to be heads or not.
- svnt 3y agoThis discovery is to our understanding of starfish what Georges Cuvier’s discoveries of vertebrate morphology were to your present understanding of whales.
- twic 3y agoWords only have meanings in context. It might now be that in the context of developmental biology, starfish have heads. It is surely the case that in the context of millinery, they do not. But no particular context is canonical, and so you cannot say that in an absolute, context-independent sense starfish do or do not have heads.
- Sharlin 3y agoFor legs and their homologues we have the word "limb" (or should I say fins and their homologues? After all, cladistically we're all fish!) but there hasn't been a need for a term for "head and its homologues". At least not until now, I guess.
- pohl 3y agoThe pointwise measurable signatures of genes expressing for head vs trunk kind of deflate that perspective a tad.
- chimpanzee 3y agoArm yourselves! The head of the language police has arrived To butt his nose into your thoughts To tell you what is meant to be or not. This mouthy busybody rarely rhymes and always prefers others mime. Metaphors, just confusing bores. Similes, not much more. If Orwell had a Frankenstein, he might to us remind: “An elbow is L-bowed only some of the times!”
- kylebenzle 3y agoYou are exactly right and wrong. I teach biology at OSU and tease my students by asking, "Do humans have gills?" Do we? What would you answer? Then, "Do humans have tails?" Do YOU have a tail? The answer to both, in biology and evolutionary, YES, we have both. In the case of echinoderms what they have now "used to be" a head, so they are a head.
- mcpackieh 3y ago> The answer to both, in biology and evolutionary, YES, we have both. But only in those limited contexts is it true, and even then there are caveats. For instance biology textbooks will tell you that great apes are tailless primates. And in virtually any practical sense that's true. You can't yank a gorilla or a human by the tail. You can't get your tail caught in door. Your pants don't have a hole for your tail to poke through. If you told a child that gorillas have tails, you would be seriously misleading that child even if in some technical sense it was true. You would have to explain that gorillas only have tails in a very specific technical sort of way. If you aren't trying to be cheeky and entertain students with counterintuitive claims, then you would say that great apes have coccyxes, e.g. tailbones, which are the remnants of lost tails. How about this: Are whales fish? In the traditional sense, a fish is an animal that lives in the water, so whales (and starfish) are plainly fish. But anybody who has ever heard from marine biologists will exclaim that whales certainly are not fish, they're marine mammals. People will be very annoyed with you if you ever call a whale a fish, they'll take it as an insult to whales. But all mammals, including whales, are tetrapods and descended from an ancient lobe-finned fish. So in a cladistic sense you can claim that whales are fish. In the same sense, humans are also fish. And why not? As you say, we have gills too!
- kylebenzle 3y agoYou are not correct about a lot of what you are saying. Whales are not fish, but birds are dinosaurs, and humans have gills and tails, but your made up version of "whales are fish" might sound superficially similar but its not how any of that works. You can not "claim whales are fish" but humans do have gills and those are not the same thing, you are just confusing the two examples because they sound the same.
- TheBigSalad 3y agoI belive they are only saying the beefy center of the starfish body evolved from a head with legs, rather than a body with 5 legs. It doesn't mean we have to label it a 'head', but that language helps people understand.
- xg15 3y agoI think the more amazing insight here (not a new one though) is that "head" and "torso" aren't just human categories, they are at the root of some very old genes that govern body development for a vast number of species. So starfishes are "heads without bodies" in the sense that they use the molecular/genetic mechanism that in other species shapes the creature's head, but use it here for the entire body.
- bee_rider 3y agoIt turns out they are four dimensional being just poking their heads into our universe to look around.
- jbernsteiniv 3y agoNo wonder Patrick from Spongebob is always so enlightening.
- brookst 3y agoFive dimensional, I would hope
- alanbernstein 3y agoWhat can this be called besides "evolutionary decapitation"?
- philipswood 3y ago"Evolutionary capitation"?
- kbenson 3y ago"Evolutionary decorporation"?
- kylebenzle 3y agoEchinoderms didn't "lose a head", that makes no sense. Of course they are just an animal with multiple life stages.
- Tagbert 3y agoQuite the opposite. It is really decorporation or hypercapitation.
- bloopernova 3y agoStarfish are bizarre. They start as a bilaterally symmetrical larva, then grow a stalk that attaches to the sea bed. They grow, then rearrange themselves into a pentaradially symmetrical form. https://en.wikipedia.org/wiki/Starfish https://en.wikipedia.org/wiki/Starfish Plus they can regenerate from a severed limb! Creepy, but very interesting too.
- polishdude20 3y agoJellyfish are really weird too. They produce like spores that then go down to the surface and create factories that create little baby jellyfish.
- Obscurity4340 3y agoWhat do you mean by "down to the surface"?
- polishdude20 3y agoI mean the sea floor haha
- Obscurity4340 3y agoWhy do you have to be so affable about it ;)?
- permo-w 3y agoif they can regenerate from a severed limb does this mean they can be cloned into 5?
- simcop2387 3y agoMy understanding is that they can regrow from all the severed parts if done correctly, so 6 at a time. Arms and central core.
- csours 3y agoIf alternative forms of cognition are your jam, consider giving the Children of Time series a read: https://en.wikipedia.org/wiki/Children_of_Time_(novel) https://en.wikipedia.org/wiki/Children_of_Time_(novel) Note: I would consider this series science fantasy, not science fiction. I had to kind of unfocus my critical perspective to enjoy it, but I really did enjoy it.
- knodi 3y agooff topic question, whats the difference between science fantasy and science fiction?
- deleted 3y ago[deleted]
- bjelkeman-again 3y agoScience fantasy, something like Star Wars. Magic in a setting that seems technical. Science fiction, only break a few laws of physics, the fewer the hard the science fiction.
- csours 3y agoMagic - or - something that sounds science-y but probably is not possible. I call this one science fantasy because there are some big science gaps that are not filled in, so that the story can happen. It makes a better story, but it is not so scientific.
- dsr_ 3y agoWith science fiction, the author describes how things work in enough detail that you can definitely tell that it won't. In science fantasy, the author glosses over the explanations and just shows you the effects. In fantasy, the author doesn't care about how it violates known science. (Technically, fantasy is the root of all literature, but these are the marketing categories we have today.)
- 3y ago
- eggy 3y agoSo Patrick is really an old starfish then. He has a torso! I get vibes of HP Lovecraft's "At the Mountains of Madness" when it describes the creatures in Antarctica.
- tracerbulletx 3y agoEvolutionary developmental biology is the coolest dang thing out there.
- c048 3y agoLink to the study: https://www.nature.com/articles/s41586-023-06669-2 https://www.nature.com/articles/s41586-023-06669-2
- Moldoteck 3y agoDoctor who predicted this with the face of boe!! At this point it's evident how starfish will evolve in the future...
- chrisweekly 3y ago"with the face of boe"?
- croisillon 3y ago(the series) "Doctor Who" predicted this with (their character) "The Face of Boe"
- chrisweekly 3y agothanks! (surprised I missed this ref since I was "Whovian" for much of my childhood)
- classichasclass 3y agoWonder if the same thing applies to sea cucumbers or crinoids.
- adrian_b 3y agoFree version of the research paper: https://www.biorxiv.org/content/10.1101/2023.02.05.527185v1 https://www.biorxiv.org/content/10.1101/2023.02.05.527185v1
- HocusLocus 3y agoObligatory "I'm Sorry, Spongebob!" https://i.imgur.com/fGB9eDF.jpg https://i.imgur.com/fGB9eDF.jpg