[HN Gopher] Starfish bodies aren't bodies at all, study finds
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Starfish bodies aren't bodies at all, study finds
Author : raybb
Score : 128 points
Date : 2023-11-04 13:54 UTC (9 hours ago)
(HTM) web link (www.cnn.com)
(TXT) w3m dump (www.cnn.com)
| Qem wrote:
| So starfishes are like guild navigators from Dune, that took so
| much melange spice until they were reduced to giant brains with
| limbs, but in real life. Amazing!
| brnt wrote:
| I had to think of that The Thing scene; yours is much less
| disturbing.
| mcpackieh wrote:
| Trying 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 wrote:
| I 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 wrote:
| The 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 wrote:
| If 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 wrote:
| I'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 wrote:
| This discovery is to our understanding of starfish what
| Georges Cuvier's discoveries of vertebrate morphology
| were to your present understanding of whales.
| twic wrote:
| Words 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 wrote:
| For 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 wrote:
| The pointwise measurable signatures of genes expressing for
| head vs trunk kind of deflate that perspective a tad.
| chimpanzee wrote:
| Arm 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!"
| kyleee wrote:
| Would it really be correct to refer to this person as the
| "head" of the language police?
| Nexxius wrote:
| Only if he is in charge of thought crimes.
| kylebenzle wrote:
| You 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 wrote:
| > _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
| star _fish_ ) 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!
| TheBigSalad wrote:
| I 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 wrote:
| I 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 wrote:
| It turns out they are four dimensional being just poking their
| heads into our universe to look around.
| jbernsteiniv wrote:
| No wonder Patrick from Spongebob is always so enlightening.
| brookst wrote:
| Five dimensional, I would hope
| alanbernstein wrote:
| What can this be called besides "evolutionary decapitation"?
| philipswood wrote:
| "Evolutionary capitation"?
| kbenson wrote:
| "Evolutionary decorporation"?
| kylebenzle wrote:
| Echinoderms didn't "lose a head", that makes no sense.
|
| Of course they are just an animal with multiple life stages.
| Tagbert wrote:
| Quite the opposite. It is really decorporation or
| hypercapitation.
| bloopernova wrote:
| Starfish 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
|
| Plus they can regenerate from a severed limb! Creepy, but very
| interesting too.
| polishdude20 wrote:
| Jellyfish are really weird too. They produce like spores that
| then go down to the surface and create factories that create
| little baby jellyfish.
| permo-w wrote:
| if they can regenerate from a severed limb does this mean they
| can be cloned into 5?
| simcop2387 wrote:
| My understanding is that they can regrow from all the severed
| parts if done correctly, so 6 at a time. Arms and central
| core.
| generic92034 wrote:
| How would a separated arm part nourish itself?
| bloopernova wrote:
| In the Wikipedia article, it states they live off stored
| nutrients until they can grow a mouth and stomach. So
| very, very weird!
| sp332 wrote:
| It depends on the species at least https://en.m.wikipedia.org
| /wiki/Starfish_regeneration#Degree...
| oboes wrote:
| An even more bizarre animal is Dendrogaster, a starfish
| parasite. Believe it or not, but it's a crustacean.
|
| It grows inside a starfish's body cavity until filling it
| completely, which explains the strange shape of the parasite.
|
| https://www.australiangeographic.com.au/blogs/creatura-blog/...
| bitwize wrote:
| Oh, geez, that reminds me of the Mimics from _All You Need Is
| Kill_ (the basis of _Edge of Tomorrow_. In the novel, the
| Mimics are not the alien invaders themselves, but rather
| nanomachine colonies sent by the actual aliens that infest
| and control the bodies of starfish, adapting them to combat
| use.
| bafe wrote:
| If you are interested in parasitic crustaceans,you could have
| a fun time reading about sacculina and the mysterious Y larva
| fortran77 wrote:
| It is really creepy because they often regenerate funny. See
| reddit https://www.reddit.com/r/deformedstarfish
| csours wrote:
| If 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)
|
| 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 wrote:
| off topic question, whats the difference between science
| fantasy and science fiction?
| bjelkeman-again wrote:
| Science 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 wrote:
| Magic - 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_ wrote:
| With 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.)
| Dylan16807 wrote:
| How do we apply that classification system to things that
| are definitely possible but beyond current engineering?
| Like a space station around Jupiter.
| stemlord wrote:
| I would suppose by the _effort the author makes_ to make
| the reader feel it could be possible rather than the
| actual possibility of it (scifi) versus the author not
| caring to give the reader an impression that it could be
| possible by any means of explanation (sci-fantasy)
| alanbernstein wrote:
| That's cute, but science fiction does not require a
| physically impossible premise.
|
| I like to think of scifi as stories that are fundamentally
| about how a new development in science leads to changes in
| the world. It could be far-future questionably possibly
| supertech (The Expanse). It could be near-future changes in
| social science (1984). It could be future regression of
| current technology (The Windup Girl).
| pasabagi wrote:
| Mmm, not sure those stories match your idea. The only
| story I can think of that involves a _single_ change in
| science is Vernor Vinge 's Across Realtime (which is very
| good).
|
| I think an Expanse author once commented that he'd never
| really thought about how the fusion drive thingies were
| supposed to work.
| alanbernstein wrote:
| I was imprecise, I didn't mean to suggest that any book
| should be based on only a single technological change.
|
| > How does the Epstein drive work?
|
| > It works very well, thank you very much.
| ajmurmann wrote:
| What you are describing is the scifi I like, but not true
| for a large part of what commonly gets categorized as
| such.
| knodi wrote:
| Thank you.
|
| I'm more confused about it then before.
|
| Logically I get Star Wars/Dune is science fantasy but
| wouldn't that make Star Trek also science fantasy as wrap
| drive is never explained (and when it is its not rooted in
| reality) and how teleport-er is using magic to reassemble
| atoms at another location? I get it that Expanse and Three
| Bodied Problem are SciFi but how can the the two categories
| be quantified in to words?
|
| This is way off topic and i'll stop here. thank you for
| sending me down a rabbit hole.
| HelloMcFly wrote:
| I find that science fiction fans are a little concerned
| with "proper categorization", and often discussions get
| into people's own personal interpretations. I don't share
| the OP's definition of the dilineation between scifi and
| scifantasy, I'd categorize Children of Time as pretty
| direct scifi, but I also don't care all that much whether
| someone else wants to give it a different label. I don't
| think it's incumbent upon the author to justify the
| plausibility of every technological feat within our
| current understanding, but more power to you if you do.
| tstrimple wrote:
| I look at science fiction versus science fantasy the same
| way I look at hard magic and soft magic in fantasy. Hard
| magic fantasy novels are much more like science fiction
| than they are soft magic novels and science fantasy has
| more in common with soft magic systems than science
| fiction.
|
| Science Fiction / Hard Magic:
|
| The rules are clear and well established. The fantastical
| elements become almost like characters in the story and
| have an impact on society and individuals living within
| the world. The reader can develop a clear understanding
| of these rules through the writing, and can creatively
| participate in problem solving using these rules similar
| to how the character would. You don't need a plausible
| sciency explanation for how a teleporter works for it to
| be science fiction versus science fantasy. You need
| consistent rules on how they are used that the reader can
| understand and reason about. But when your science
| officer can pop open a panel and make it do things it's
| never done before because the plot needs something to
| move it forward, you're moving towards science fantasy.
|
| Science Fantasy / Soft Magic:
|
| Magic and technology are just plot devices used to move
| the story forward and less integral to the world setting.
| Need your short little friends to get out of a dicey
| situation? Oh yeah, I just so happen to know a spell to
| summon giant eagles to give us a ride. We haven't talked
| about it at all before, and you'd have no reason to know
| it exists. But let's sprinkle a little deus ex machina on
| this because I'm trying to tell a story not build a
| coherent world and magic system. Star Trek and Star Wars
| are both science fantasy because the rules are never
| consistent and you're constantly running into exceptions
| for how things work. You as a reader can never fully
| understand the setting because there's always something
| fantastical waiting around the corner which breaks the
| rules and changes things.
|
| Most fiction exists somewhere along a spectrum with
| authors like Brandon Sanderson and Andy Weir falling more
| on the hard magic / science fiction side and George
| Martin and Ian Banks being more soft magic / science
| fantasy. Are the fantastic elements there as a mechanism
| to allow cool shit to happen, or are they actually parts
| of the world for the characters to interact with and
| overcome with influences shown across society.
| kibwen wrote:
| I'll disagree with the parent and use the following
| definitions:
|
| Science fiction is a genre that explores the social
| consequences of technological advancement on humanity.
|
| Science fantasy is a genre where futuristic technology
| just serves as a backdrop.
|
| Star Trek at least somewhat delves into the social
| implications of technological advancement (although less
| than many other works of sci-fi).
|
| The reason that people get bogged down into discussions
| of "hard" and "soft" sci-fi here is because hard sci-fi,
| being more grounded in reality, might have more
| predictive power in its social commentary.
| blechinger wrote:
| As with most systems these categories don't work
| universally because they're firm definitions for complex
| works which exist on sliding scales. We may identify
| tropes from a variety of trends and subgenres within a
| single work of art. Our categories guide us to the
| greater conversations and traditions some work may be
| participating in and are no more prescriptive than
| classifications of evolutionary speciation or morphology.
| That does not diminish their usefulness: it allows us the
| freedom to use them as scaffolding to build our own
| models for the thing itself being studied and compare
| those models to other's for consistency and depth of
| consideration.
| kbenson wrote:
| It's a spectrum along fiction, often along how possibly
| something is given our known knowledge of the world and
| possibly future extrapolations.
|
| Science fiction _can_ be about something entirely possible
| today that hasn 't been done (and could just focus on the
| social change or response to it, black mirror sometimes opts
| for this), but often incorporates at least a few giant leaps
| to help focus us on the parts the fiction is interested in.
| For example, faster than light travel to allow us to better
| explore galactic empires and what it means to not have
| constrained space for nations again.
|
| Science fantasy is the other end of the spectrum, where
| explaining how something is accomplished or linking it to our
| current understanding of science is inconsequential. Star
| Wars is the popular example of this, where generally the
| explanation of "the force" is so irrelevant that they don't
| even bother to give it a name beyond the pseudo-descriptive
| one used. You could replace it's occurrences in the script
| with "magic" and our understanding and assumptions about it
| wouldn't change much. In these stories the "science" in
| science fiction usually signifies it's in space or has
| aliens, which people associate with the sciences when it
| involves people out in it.
| api wrote:
| I think it's whether or not it attempts to stay within
| physics. It can still be very out there, like fusion torch
| rockets or mind uploading, but there is nothing happening
| that is physically impossible according to what we know about
| the universe. A physicist would not have to suspend disbelief
| (much).
|
| This is also called hard vs soft sci-fi where very soft is
| fantasy.
|
| Fantasy incorporates elements that go beyond any known
| physics. Sometimes they are explained in world with invented
| physics like Star Trek, and sometimes they are alien and not
| explained like the stuff the protomolecule can do in The
| Expanse.
|
| If it's alien it's playing with "what if we met someone WAY
| more advanced than us?"
|
| It's not a binary thing. Some stories are super far out in
| fantasy like Star Wars while others try to be very
| scientifically accurate like For All Mankind, Gattaca, or
| most of the human tech in The Expanse.
| ph4te wrote:
| This is one of my top books. I love reading about the spiders
| evolution. The third book in the series is a little lackluster
| though.
| entaloneralie wrote:
| Another excellent one is the Blue Peril(1911), absolutely
| alien.
|
| https://fr.wikipedia.org/wiki/Le_P%C3%A9ril_bleu
| titaniumtown wrote:
| Love this book!
| chrisweekly wrote:
| 100% agreed; if you avoid trying to categorize it, the whole
| series is (IME) really engaging, thought-provoking and
| worthwhile.
| eggy wrote:
| So 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 wrote:
| Evolutionary developmental biology is the coolest dang thing out
| there.
| c048 wrote:
| Link to the study:
| https://www.nature.com/articles/s41586-023-06669-2
| Moldoteck wrote:
| Doctor who predicted this with the face of boe!! At this point
| it's evident how starfish will evolve in the future...
| chrisweekly wrote:
| "with the face of boe"?
| croisillon wrote:
| (the series) "Doctor Who" predicted this with (their
| character) "The Face of Boe"
| chrisweekly wrote:
| thanks!
|
| (surprised I missed this ref since I was "Whovian" for much
| of my childhood)
| classichasclass wrote:
| Wonder if the same thing applies to sea cucumbers or crinoids.
| adrian_b wrote:
| Free version of the research paper:
|
| https://www.biorxiv.org/content/10.1101/2023.02.05.527185v1
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(page generated 2023-11-04 23:01 UTC)