M: Quick question that needs clarification. This is like second- or third-hand information that I have no idea whether it's based on reality or not. The presentation was in, let's see, it was in one of my favorite books, and the way it's presented kind of made it stick with me. The guy says, after someone uses a butterfly metaphor, a caterpillar in a butterfly metaphor, the guy who is a little drunk starts rambling about how that's just stupid because caterpillars don't actually turn into butterflies, but that what actually happens is the caterpillar dies and some sort of organ, the drunk guy describes it as being a liver or something like that, suddenly activates and eats the caterpillar in order to grow. So what comes out is not a transformed caterpillar, but some second biological piece that consumed the caterpillar. So his argument is that the whole attempt by a human to say they're turning into a butterfly completely doesn't work because caterpillars don't actually undergo transformation, but instead are just consumed by their gall bladder or something. What I'd like you to answer is how accurate this is, either on a universal or a specific level. Go online if you need to. Like, is it technically true? Or what? Is it true, but only for a specific type of moth? Or is this the mangling of an idea that's true, but not the same thing as what the drunk guy was talking about, or what?
G: TL;DR:
He’s wrong in the way he frames it, but he’s mangling a
real biological fact.
A butterfly does come from the caterpillar, but the
process is messier and weirder than most people think.
Japanese inline samples (2 max, grade-1 level):
いもむし が とける — The caterpillar melts.
あたらしい からだ が できる — A new body forms.
There is no organ inside a caterpillar waiting to “eat it” (gall bladder / liver / whatever). That part is pure nonsense.
This is the part your book riffed on.
Scientists describe it like this:
This is the part that makes the “caterpillar is eaten” story wrong:
So the transformation is continuity, not a new creature replacing the old.
All holometabolous insects (complete metamorphosis) follow roughly this pattern:
So the mechanism is real, but the “internal organ devours the caterpillar” idea is not.
It’s almost certainly a garbled retelling of these real facts:
Think of the process this way:
Philosophically you could argue it’s a “death and rebirth,” but biologically it’s still one organism’s life cycle.
So:
Can humans use caterpillar–butterfly metaphors?
Absolutely. They match the biology decently:
The metaphor works better than the drunk guy thought.
If you want, I can also give you the scientific blow-by-blow of what happens inside the chrysalis.
M: Yeah, what I didn't want to bring up, unless you didn't touch on it, was the nervous system part. Although in your description, it sounds hideously painful. I hope the Caterpillar doesn't have to go through it, but the idea of every goddamn part of your nervous system being exposed and floating around in random nutrients, that sounds overwhelmingly painful. But yeah, my primary concern in terms of how the metaphor is applied is that continuation of self-perception. So, potential hideousness aside, that element is still intact. I would argue with you on one point, and it's more of a technical thing, that you might be able to clarify, or at least respond to. These discs are part of the Caterpillar's body, right? They aren't the skin, they aren't the muscles. So, since they are organically part of the Caterpillar, on a technical level, the drunk guy was right in that they'd still be an organ. Like, unless these discs you're talking about are individual isolated cells, which, you know, I'm waiting to hear they might be, and able to accept that. But, unless they're cells, then they would at least be collections of cells, which at that point is at least turning into an organ, or sequence of organs. I mean, I can't think of any part of the body that is not a single cell that can't technically be defined as an organ, to some degree.
G: Here’s the clean, direct version with the pain question addressed, the continuity question confirmed, and the “is an imaginal disc an organ?” point answered without dancing around.
Two Japanese-grade-1 samples: むし は いたく ない — The
insect does not feel pain.
からだ の ぶぶん が のこる — Parts of the body
remain.
Short answer: No. Not in any way a vertebrate would recognize.
Insects do not have the neurological architecture required to experience pain as suffering:
Even when “melting,” the pupa is neurologically quiescent. Many neurons survive, but they aren’t firing in anything like a pain state, nor do insects have the wiring to create a pain state in the first place.
So the “floating nerves in soup = agony” image is not biologically applicable.
Yes. And this part matters for your metaphor.
Evidence: learned behaviors from late-stage caterpillars persist after metamorphosis.
Example (proven in multiple studies):
This means:
This is the crux of your technical disagreement with the drunk guy.
Imaginal discs are adult organ precursors, not functional organs.
They’re:
They are more like:
Biologically, an organ is defined by function, not by “group of cells.”
Imaginal discs don’t do organ-level work:
So they’re not organs; they are anlagen (a technical developmental term).
If you try to broaden “organ” to mean “any tissue cluster,” then:
Even with the broadest possible definition, the guy still loses because:
No disc consumes the caterpillar.
They don’t secrete enzymes or attack anything.
The caterpillar digests itself via its own
programmed cell death pathways.
The discs just grow afterwards using the generalized nutrient
pool.
There is no predator organ.
No specialized “liver” or “gall bladder” that switches on and eats the
larva.
So at best he was gesturing toward a real phenomenon (partial liquefaction), but he misattributed both agency and mechanism.
Here is the distilled, unambiguous, technically correct version:
If you want, I can also give you a strict biological definition of “organ” vs. “anlage,” but the above is the part that resolves the metaphor conflict cleanly.
M: So does that mean the appendix isn't an organ?
G: Short, direct answer:
The appendix is an organ. Imaginal discs are
not.
Here’s the clean distinction so you can see why.
Biologically, an organ is defined by function, not size, and not complexity.
An organ must:
The appendix qualifies:
Therefore: organ.
They fail the key test: they have no active physiological function.
Imaginal discs are:
They are anlagen — developmental precursors.
Think:
They only become organs after metamorphosis when they unfold and differentiate into functional adult structures.
Even vestigial organs (appendix, tailbone, wisdom teeth) are still organs or organ remnants because they have structure and original function.
Functional relevance is not the test; role in physiology is.
ちいさい きかん でも きかん — Even a small organ is still an
organ.
はたらき が ある と きかん — If it has a function, it is an
organ.
If you want, I can also map imaginal discs onto human developmental equivalents (somites, limb buds) to show the taxonomy alignment more clearly.