The Truth About Butterfly Metamorphosis (It's VERY WEIRD)

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Does any other creature on Earth undergo a life transformation as dramatic as the butterfly? I think not. Unfortunately, children's books about very hungry caterpillars skip all the COOL and WEIRD and GROSS stuff that happens along the way. It's time to dig into all the mind-blowing biology behind metamorphosis!
Filmed on location at the California Academy of Sciences
0:00 We were lied to as kids
1:48 Metamorphosis is more common than you think
3:36 It starts with an egg
4:46 Eat/Poop/Grow
6:05 Busting the biggest butterfly myth of all
7:23 Time to take your skin off
8:40 Inside the "sack of magic"
11:08 Metamorphosis,… metamorphosis everywhere
11:55 Why do butterflies do this?
13:42 Sign up for our Patreon!
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[@rickseiden1]

Could you imagine if humans did this? "I'm sorry, but Johnny can't come to school today. He's locked himself in his room, and isn't coming out for the next two weeks." "That's exciting, Mr. Smith. I'm sure your whole family is very proud. Please remember that when he does emerge, he will be expected to make up the work."

[@garvgupta3567]

I laughed so loud while reading this lol

[@raraavis7782]

If only puberty actually worked like this 😂

[@vashsunglasses]

@@raraavis7782 It isn't really puberty, it's more like if humans gave birth to 5 month old fetuses and then those fetuses foraged for food for few months then created their own womb to finish maturing into a baby.

[@oracleofdelphi4533]

I would argue that humans are more amazing. It doesn't seem so as we are just more familiar. Butterfly: "Watch me metamorphosize" Human: "Watch me create a noise with my armpit"

[@jaydflay4809]

Getting COVID being like:

[@johncao6516]

Small correction towards the end: flies don't do the metamorphosis IN rotten meat or poo, they tend to stop eating and craw away from food to pupate (otherwise the adult will immediately drown as soon as they eclose). I worked with both fruit flies and blow flies in the past and you always find the pupae far away from the food.

[@pierreabbat6157]

Also, cicadas are bugs; they don't turn into pupae.

[@divingstag]

@@pierreabbat6157 Neither do cockroaches shown at 3:08

[@patrickcoin9457]

And another quibble, moths (11:20) do have a pupal skin--the silk cocoon is an additional layer over that. Also a few groups of moth do not make a cocoon--they just have a chrysalis.

[@patrickcoin9457]

@@pierreabbat6157 Right, at 11:43 he says "beetles and cicadas do it too, often buried in the ground". Beetles have complete metamorphosis like Lepidoptera, but not cicadas--they have gradual metamorphosis. Great video though, explaining a lot in a short format with excellent graphics.

[@76rjackson]

Learned a cool new word today: eclose. Sounds poetic except it's about bugs. I only know one poem about a bug: The lord in his wisdom made the fly And then forgot the reason why. Ogden Nash He never realized how cool bugs are, I suppose. I understand because I dislike the vermin very much, too, myself.

[@jimmytaco6738]

Preschool teacher: And from within the fat little caterpillar burst a writhing mass of wasp larvae that ate the caterpillar from the inside out and grew up and laid their eggs inside more caterpillars!

[@besmart]

I'd read that book

[@Cdubb1967]

I actually had that occur with a Yellow Swallowtail caterpillar I pulled off my Dill plant years ago. Instead of a regular Crysalis forming after the caterpillar attached it self, it turned black and it's mouthparts fell off. It was the first time I had collected that type, so I was not sure if this was normal or not. I waited and was very shocked to later find a very large wasp in the jar. It was pretty scary opening the jar and releasing it.

[@kearstinnekenerson6676]

That sounds like a fun book is there other type of parasitic children

[@raraavis7782]

Isn't nature magical?

[@Ender240sxS13]

​@@kearstinnekenerson6676so so many, the insect kingdom has all kinds of horrors. Some birds even do a similar thing with their young, they lay their eggs in other species nests and push out or break as many of the host species eggs as they can when they do it, and just leave their eggs there for the host species to raise.

[@OlleLindestad]

Big and important correction: moths don't spin a silk cocoon INSTEAD OF becoming a hard-skinned pupa; they do it BEFORE becoming a pupa. Cut open a moth cocoon, and there's a pupa inside it. Also, cicadas are mentioned in the same breath as beetles, but cicadas don't have a pupal stage; they're hemimetabolous. They go straight from nymph to adult.

[@mycosys]

I feel like one factor for metamorphosis is energy - the amount of energy required in the egg to create a pupal stage vs a more complex adult. The pupal stage means the mother can expend a LOT less energy and instead make hundreds or thousands of eggs that then acquire their own energy. But im an engineer - its always energy XD

[@marksando3082]

Lots of organisms have reproductive strategies that involve producing many eggs instead of investing more intensely in a smaller number of young, but also don't involve metamorphosis. How is metamorphosis specifically and separately from producing lots of eggs saving the parents energy?

[@TheMunchkinita2509]

Energy plays a HUGE part in every animal's biology, so you're not far off by thinking of it that way

[@terryarmbruster9719]

@@marksando3082 it isnt. Nonetheless its still engineering as the field also covers costs. The amount of energy invested per egg is small so total energy invested by mother gives many eggs. Engineering considers business factors too. Since there are many competitors odds of survivability are small per unit but produce volume enough .... Lol you get the idea now

[@mycosys]

@@marksando3082 clearly metamorphosis isnt the only way to have many eggs, but it seems an efficient strategy to do so. Obviously there is more than one factor to why most of the world's animals use it.

[@catherine_404]

It's mostly about organisms at different stages of development not competing for same resources.

[@MrLeafeater]

When I finish writing/illustrating "The Very Hungry Maggot", I'll expect you to review/endorse it. Love your work.

[@garethdean6382]

I believe Gary Larson already tried that.

[@richmcgee434]

That's been done repeatedly. There's a book called Brainboy and Bob in The very Hungry Maggot, another one called the Moderately Hungry Maggot, and a variety of "Very Hungry Maggot" merch, my favorite of which use a human skull and maggot in a parody of the Hungry Caterpillar cover.

[@whoisWAZz]

Username checks out

[@diyeana]

You've brought back a memory from my 5 yr old self where I squished a cocoon to see what it was all about. I buried the pulp and cried.

[@ketsuekikumori9145]

If you keep in mind that during the chrysalis stage that hard shell on the outside was once the exoskeleton of the caterpillar before metamorphosis, it makes sense that it has protowings and such.

[@kienesel7]

I’m genuinely surprised the chrysalis is inside the caterpillar and they just reveal it. Somehow more disturbing.

[@TheMunchkinita2509]

The butterfly wings are kinda like our 2nd set of teeth.. already there but just under the surface where we can't see it.. pretty cool

[@RJ_Ehlert]

Imagine parents consuming all the resources in an ecosystem and blaming the children for not having enough.

[@jamesehlenfeldt7132]

Oof

[@Not.Your.Business]

shots fired!

[@ConnorNolan]

Maybe my grandchildren will be able to afford a house as long as I don’t spend anything on healthcare

[@LineOfThy]

Damn, shots fired!

[@renmacrae5924]

Average boomer

[@ntt2k]

"This isn't kids book stuff, this is more like Silence of the Lambs." I wonder how Joe teaches his kids about the facts of life😂

[@garethdean6382]

"Now bedbugs, BEDBUGS do something called 'traumatic insemination', are you paying attention?"

[@arisis6709]

I have a fear of butterflies and am trying to reduce it gradually by exposing myself (virtually) and learning about them. This was really cool to watch :)

[@Ziorac]

...Not sure this video is gonna make your fear go away though.😅

[@TheMunchkinita2509]

I do the same with spiders! However, I can still only do it with pics or videos. Irl I wanna die 😅😅

[@Splarkszter]

Butterflies do nothing, is from wasps that you have to fear.

[@ForestFire369]

Do you know where that fear originated? I've never heard of someone being afraid of butterflies before & I'm really curious. Sorry if that's a weird thing to ask lol

[@EmilySmirleGURPS]

@@ForestFire369 I've seen it before. Sometimes as part of a larger fear of insects, but sometimes just independent "creepy flappy thing eugh" horrors. Not me, I get the horrors about slugs instead - I'm OK with pictures and video but I am NOT getting near one. Calvin said it best: "Living booger"

[@Tser]

My sibling worked at a neurology department in their moth lab. They used the metamorphosis of sphinx moths to study neural development!

[@risooo2274]

this is sooo niche omg ur sibling has a very cool job

[@pyro-millie5533]

Dude that’s so metal whoaa

[@devaraiuzuchiha1982]

Sounds really awesome, do you remember which lab it was?

[@Tser]

@@devaraiuzuchiha1982 OHSU!

[@mapples007]

Moths are better than many people.

[@LeoAngora]

It seems to me that caterpillars are just a second stage of embryonic development, but external and more autonomous. Since the egg does not have enough nutrients, they must eat to continue their development. Once they secure enough food, the final transformation is done.

[@vashsunglasses]

Yep, that's exactly it.

[@OlleLindestad]

This is, in fact, a decent summary of the prevailing model for how holometabolous development evolved. The pupal stage is believed to correspond to the nymph stage in non-metamorphosing insects like grasshoppers, while the larval stage is thought to correspond to a kind of mobile late-stage embryo called a pronymph.

[@toolbaggers]

What's even weirder is the life cycle of the malaria parasite.

[@erinm9445]

That's exactly how I think about it. Kinda reminds me of how a lot of people call the first three months of a human baby's life the fourth trimester, the final trimester of development that happens outside the womb, before they really start becoming interactivec and learning how to human.

[@youngspaghettii]

​@erinm9445 the reason for this on humans is our huge heads. If babies were brought to "full term" based on mammal biology their heads would kill the mother almost 100% of the time (before modern medicine obviously). Most other mammals can at least walk and see when they are born (as with horses) or at most take 3 or so weeks before they can (as with dogs and mice)

[@urphakeandgey6308]

I think you missed out on the most interesting aspect: Butterflies remember things from their caterpillar days. Let me remind you they turn into insect goop while inside the chrysalis and then re-assemble.

[@erinm9445]

Your first sentence is true. But this video shows that your second--though widely believed and taught--is an oversimplification at best. There's no reason to think that the brain of the organism is turned to goop during metamorphasis. But I still agree that butterfly/caterpillar memory is super cool!

[@littlerave86]

Couple years ago I had a cabbage white in my living room and let it out. More than half a year later I found its crysalis hidden behind the door inside of my fridge, where it apparently ended up as caterpillar with the groceries. Despite the cold, it pupated and eventually hatched. I also found another one next to it, which didn't hatch yet, I could feel it bobbing around carefully shaking the crysalis. I assumed it dead, took both crysalises out and ordered some resin, colours and tools to make fake amber earrings with the crysalises inside. After a week of lying on a table in the warm living room, while I was waiting for the supplies, the 2nd one miraculously did hatch as well. I guess the cool environment inside the fridge basically told it to lay dormant and wait for spring before hatching, which then it did. I was amazed.

[@erinm9445]

I also found mystery cabbage moths in my living room one day. Or rather, one one day, and another a few days later. I don't know why it never occured to me that they must have pupated right in my house! (I don't recall finding the chrysalis later, but who knows, it was quite a while ago now). Neat story!

[@ckq]

I haven't thought about this in 10+ years, so thinking about it seems like magic how a bug turns into a butterfly

[@kindlin]

Does that mean a butterfly isn't a bug?

[@toolbaggers]

What's even weirder is the life cycle of the malaria parasite.

[@brandon8900]

I raised a monarch from caterpillar to butterfly last year, it was fascinating seeing them change. The end of the period they are in the chrysalis it turns clear

[@garethdean6382]

It's always clear, it's the butterfly's forming body that's changing. Amazing the fine scales on the wings can form in just a day or two.

[@Beryllahawk]

As a matter of fact, no we didn't raise any butterflies in school. HOWEVER. The school I attended for 3rd grade and 5th grade (don't ask, Midland Texas has WEIRD school district lines) had a "caterpillar problem." Every year in spring there would be absolute hordes of itty slightly fuzzy pale green caterpillars, all over the ornamental plantings but also all over the walls!! A lot of the kids were freaked out by them but I was always fascinated since I knew they weren't going to bite or sting me, and finally one day in 5th grade, I caught one of the caterpillars and very carefully brought it home with me. My mother did not flip her lid, and instead gave me a glass jar to put the creature into, and told me to go outside and pick three stems off the ornamental bushes in the apartment complex, but ONLY the ones that looked just like the bushes at the school. (At that age I already knew my mother was smart, never even questioned it, ha) She fixed up the jar so that the caterpillar couldn't easily crawl out, and we gave it its food and it was chill! I would get it onto my finger for a few moments every day just because I could, and I'd bring home a new stem every day with more leaves. Then - the weekend. Saturday morning - and my caterpillar had vanished!!! I looked high and low (well, as "high" as a nine year old can look) and couldn't find it. Very sad. But SUNDAY morning I saw the pupa!! The caterpillar had managed to get out of the jar and made its little sack of magic on the curtain. Few days later - and there was a moth!!! A beautiful white moth with vivid tiger-orange on the inside of the wings. And though I know now as an adult that bugs don't exactly bond with anything or anybody, it seemed to me like the moth remembered me, and it flew over and landed on my shirt and just kinda sat there like "Welp. Outside now, please." So of course I took it outside, set it carefully on a bush, and watched it fly off to do whatever moths do. And at the school? Dozens and dozens of white-and-orange moths on Monday! So many! The grownups were all super annoyed but to me it was pure magic. To this day I have no bloody idea what kind of moth it was though. I've never found ANY picture that looks like my moth pal.

[@erinm9445]

Wow, what a great story! Now I really want to know what kind of moths they were, but I did just go down a little google images binge looking at all of the different moths with white and orange wings. There are so many beautiful kinds! As for a moth bonding with you, I wouldn't rule it out! There's good science showing that adult insects retain memories from when they were in their larval stage, and there is also increasing evidence that insects have emotions! If nothing else, it sounds like the moth knew you were trustworthy!

[@Beryllahawk]

@@erinm9445 There ARE so many pretty moths with those colorations! I've gone down that image path a few times too hehe, it's never disappointing.

[@diaryofablackspinster]

I know multiple people who are scared of insects, even “pretty” and harmless ones like butterflies, despite not having bad experiences with them. I’m sure you have a video posting schedule but it would be neat to explore what draws out the natural fear of these things in a future video :)

[@TheMunchkinita2509]

My BIL is one of those people. If it has 6-8 legs he ain't dealing with it 😂

[@Byter09]

It all started with that one scene in Spongebob.... God it was awful.

[@shadycactus6146]

for me, at least, it tends to be a combination of unpredictable/fast movement and small fragile bodies (i.e. i’m afraid i might hurt it by accident)

[@b.a.erlebacher1139]

The definition of phobia is more or less a morbid fear of something that isn't dangerous. People with phobias are quite aware that their fear isn't rational. We have deep-seated mechanisms for developing fear of dangerous things as we encounter them, and sometimes this goes wrong. The good news is that treating phobia is probably the most successful psychotherapy there is. So if you have a phobia, know that you can get rid of it with known, successful methods.

[@ForestFire369]

​@@TheMunchkinita2509That's exactly my problem with spiders and centipedes. Too many legs.

[@TonyTylerDraws]

We had a bunch of caterpillars for a school project. Some metamorphosed just fine, some died before they had the chance, and some seem to never make a chrysalis and just turned to goo? We never found bodies but there was goo.

[@dilophosaurusking7437]

Odd

[@ForestFire369]

missed a step

[@EmilySmirleGURPS]

If I remember correctly, the goo is because after they die, the hormones and chemicals that were directing unneeded cells to recycle themselves are out of control, so the whole pupas corpse "recycles" itself. I'm having trouble finding confirmation, the internet just keeps giving me "caterpillars turn into soup" stuff. Vertebrates get attacked by our digestive acids, enzymes, and symbiotic bacteria after death too, but it's not as extreme because we're never in the middle of trying to completely redo our architecture.

[@wesleyson21]

Yeah a fair number die during the many molts that they have to go through as they grow. That and eclosing in to an adult are the riskiest times for them and when things tend to go wrong.

[@garethdean6382]

The goo ones are because of a viral infection, they liquefy and are picked up by other wandering caterpillars, continuing the cycle. The gypsy moth baculovirus is an especially ingenious version of the parasite.

[@ForestFire369]

I feel like the butterfly goo myth originated when somebody tried to open a pupa to look, its guts came out, and they just went "Welp I guess that's all there is in there!"

[@OmateYayami]

This is super interesting. Also a bit more approachable but on par in weirdness is that an egg containing of inconspicuous white and yolk that probably each of us ate on breakfast at some time... consists all ingredients to make a whole small bird. Given the egg is fertile it contains all the resource and bioengine to transform it into a bird, from some bio-mush. In that sense it's like chrysalis.

[@richmcgee434]

Not really. Butterfly species still lay eggs themselves which hatch to produce live young, which is perfectly conventional. They just pause at the end of the larval stage to undergo a second transformation into the adult reproductive stage, which is a less common reproductive approach. The genes for the butterfly are the same as the caterpillar that presages it, they're just being expressed differently until the hormonal triggers are released. The shell of an egg is (from a human viewpoint) much closer to being a self-contained external uterus than anything else. The resources needed for the embryo to develop are pre-loaded rather than being drip-fed over time the way things work in a mammalian womb, but otherwise the functions are essentially the same. Both approaches have their own biological advantages and drawbacks.

[@toolbaggers]

By that logic a 'woman of the night" has consumed half the ingredients for a civilization.

[@HPDevlin]

I wonder, did all these genera of pupating insects independently evolve their pupating strategies, or did they diverge from a common ancestor only after it adopted the pupating strategy?

[@rouelejour4080]

Me too! Anybody know?

[@jjy1874]

What are you talking about? Evolution is false.

[@OlleLindestad]

It evolved once. The insects with a pupal stage form a single branch on the insect family tree, called the Endopterygotes.

[@Dynamaximometer]

I'm real curious as to how this process originated. It's such a drastically different life stage from what other species do it's hard to imagine how they might be related.

[@bobtuckey2409]

Hi Joe, Bob here. Another amazing show. I also used to catch caterpillars and watch them pupate and emerge as butterflies. It was fascinating. And still is.

[@IanTindale]

One further interesting tiny point that I find fascinating and inexplicable is the very small period of time when the chrysalis, if it is one that hangs downward from the tail (not all do, some are suspended upward with a silk waistband, some are in cocoons such as with moths) has to shed the skin of the final instar of caterpillarness, which becomes a crinkled up bundle, and then the chrysalis (blind) has to walk with it's tail hooks (which are like hook&loop fastener) across the drying bundle of shed skin, and onto the silk pad onto which it hooks and stays - that’s not only amazing it can do this every time, but that it has ‘knowledge’ to do this specific one-time action, and seriously, how did that evolve, there must’ve been so many that fell off and didn’t survive? That’s certainly one for Darwin if you ask me

[@andrewf2630]

the genetic coordination involved, first evolving an organism like a caterpillar which itself has thousands of parts which have ireducible complexity, and then the whole organism , for one, how did the caterpiller movement spring forth out of.nowhere, one day no caterpillers, the next, a whole new organism with hundreds of different protiens. And the way they move, coordinating all their legs to.move at the right time, im sceptical of the scientiic theorys proposed about competition. Sometimes scientists want to be sound right becaise they dont like to appear to have an incomplete understanding How the butterfly completely changing shape and function 4 times could have evolved purely by chance. You can't tell me this process evolved by chance, It seems designed, like the cell. Irreducible c complexity. Ohh and it doesn't explain how these processes evolving by adaptation, mutation and competition, how ststistically its nearly impossible to have evolved by chance. Im not a creationist,im atheist, but this has always been a mystery to me.

[@jennypai3763]

13:54 Joe talking with his hand shaking the chrysalis back and forth 😂I was like, "you're going to shake it off the branch!" imagine the pupa going "ohmygod everything's shaking it's the end of the world!!!!!!"

[@briank326]

Thank you so much for this video! A few times now I've gotten really curious on what exactly is going on inside a chrysalis but had never been able to find anything remotely detailed enough. This not only provides some good detail into what's going on but also contains some really mind-blowing stuff, such as the imaginal disc starting to develop prior to the pupal stage.

[@SavannahBurris]

I got up close and personal with some butterflies while camping and even as an adult it’s just such a joy to see them! It’s like a welcome visit from a friend, and I always talk to them as they fly by. I’d always wondered what went on in there 😊

[@martinmarkov9707]

Flight, forage, fornicate, futile.

[@ruudhollenberg]

Omg I didn't know scientists had figured this out. The last thing I heard (long time ago) was that it wasn't known what happens. I always wanted to know this. Thank you so much!

[@OlleLindestad]

Yeah, that's also a myth. It's been known roughly what goes on during metamorphosis since at least the first half of the 1900s, although with new tech like x-ray tomography we can get way better images of it now - earlier research relied heavily on things like dissection and transplantation of developing organs.

[@Wolf-tk6dk]

Heh I taught myself that chrysalis are just another layer under the skin while reading my own caterpillars. Also moths do the the same, they just do it inside the cocoon. Certain ones like the gypsy moth will even just make a super lazy cocoon, just folding a leaf partially together.

[@SuiLagadema]

School taught me the version of Caterpillar -> Chrysalid -> ? -> Butterfly. I'm 33 and I'm ashamed of myself for never actually questioning "Huh, what does really happens to that caterpillar once inside"

[@xamishia]

Cool. Suggestion: for shots that are sped-up or slowed down, always add the speed in the corner (like "x100 speed"). It's science communication after all. Thanks.

[@viljuska7844]

i love how much comedy effort is put into making into all of yours videos

[@verdantpulse5185]

Not just cannibalistic caterpillars. I had some shaped like inch worms preying on aphids, on some umbelliferous plants one year.

[@Rennanbarbosa0]

Great video! I was trying to research that exact things a while ago but I couldn't find it in a way that I would understand, now I did!

[@ldmonul22]

Woooow!! I wish there was a super like button on KZbin to smash it right now! I love this video, I had always wanted to see the inside of a chrysalis and thanks to your flawless explanation now I understand metamorphosis way better. Thank you for your work! 🙏

[@candycemonroe7345]

Eric Carle fan. He actually wanted to write a book about a bookworm. His publisher or editor wanted the change. He just wanted to make a book with fun holes in it. A lot of his books have fun tricks to them.

[@tanostrelok2323]

I have been wondering about this in particular for quite some time, thank you for uploading this.

[@shadowscribe]

It's a little more horrifying to know the foundational elements of the butterfly are developing within the whole time. Its less you assuming a new form, and more your existence is fueling this second lifeform eventually taking over. Like it started with a parasite and they linked life cycles.

[@erinm9445]

It's all one brain the whole time, so I think it's okay! Think of it more like permanent teeth vs baby teeth. The permanent teeth are in there forming long before you lose your baby teeth and the adult teeth come in, but all of it's you the whole time, the adult teeth aren't the foreign teeth of some weird organism living through you!

[@clivematthews95]

This is my favorite video of this week 😊 Very cool, everything I saw here. I always wondered about the pupa stage 🤔🙏🏾

[@hcn6708]

3:09 Gonna have to point out cockroaches are NOT holometabolous, they do not pupate and the nymphs look like smaller wingless paler adults

[@Konekoexe]

Thanks for this video. Always wondered what was going on in there

[@user-fy8dg5xq4s]

As an ex-preschool teacher I had A very ambivalent feeling about "the very hungry caterpillar." But I always told the children that not all of the story is scientificly accurate. Not only what happens in the pupa. I don't appreciate when people accuse preschool teachers of all the misconceptions people have when they grow up.

[@akmartinez419]

Very interesting video! We just became a Monarch Waystation about a year ago. Last fall was our first time rearing , tagging and releasing Monarchs. It was the most amazing process but watching them emerge was probably by favorite. It’s a lot longer process than I thought, they typically stay a good hour or so in the same position just swinging back and forth and pumping their wings. We have only had one bad chrysalis so far so not a bad record!

[@maxgluteus4263]

I am so glad you recovered!

[@drhat77]

It's an example of the Swiss Army Knife effect - if you have a tool that can do a bunch of different things, it will do them all but poorly, like a swiss army knife. By confining the eating and growth phase to one body plan, and the mating and reproduction phase to another body plan, each body is optimized to that task. All life forms and functions strive for maximal energy efficiency.

[@davidripley2916]

Hi Joe, when I was a kid my granddad found a thumb-sized black caterpillar covered in hairs. He put it in a plant propagator box with a privet twig. Days later, it pupated. Turns out it was a beautiful Privet Hawk Moth, with magenta and lime green wings. It did its first crap on my thumb, and fed it with sugar water on a microscope slide. I never forget it warming up its flight muscles by vibrating. We released it shortly after, and it remains my fave childhood memory.

[@A3Kr0n]

In the United States, students are typically taught about butterfly metamorphosis in elementary school, specifically during the early grades. The age at which students are taught this subject can vary by school district and state, but it is commonly covered in early elementary grades, such as kindergarten through third grade.

[@alllove1754]

There is so much about our very souls that you may have very well shown us today/tonight, good sir. This was awesomely informative. Thank you!!

[@shuckieddarns]

I love the closed captions, especially towards the end

[@Areaninetyone]

Well over 15 years ago as a child I would bring this up to family and teachers that I believed the inside of a chrysalis was liquid and I wanted to order some caterpillars and open them up mid metamorphosis to prove my theory.So you better believe I was so excited to learn the truth about them when I got older

[@darcieclements4880]

Complete to incomplete metamorphosis is a spectrum. Different species, different amounts of development per molt. The goo is just an over simplification and there are many pupa that are strongly dominated by goo rather than structures visible to the naked eye. In some butterflies you can see into the matrix as the structures develop. I recommend swallowtails. Cicadas are usually classed as incomplete metamorphosis, not complete, which is to say the structures grow strongly between each molt with less goo so they don't suddenly dramatically change form, you can see this in the casts left on trees which are nearly identical to the adults minus wings and a few other changes.

[@GardenUPLandscape]

By far the best and most comprehensive video on metamorphosis I have ever seen! Possibly the best on the internet! ❤️🦋❤ Not to mention entertaining! "Eric Carle didn't mention that part did he!?!" 🤣

[@thethirdjegs]

I was so excited at the start, it felt like i was about to watch pbs be smart, pbs eons, & just keep thinking in a single episode. Please check the last one too. I hope scientists would discover how holometabolous development evolved soon.

[@Ben-Hollingbery]

When I was a child, I wanted to go to university to be the first person to figure out how catapillars become butterflies because it seemed like no one knew.

[@nyuh]

yes i know this fact because theres this visual novel game thing titled butterfly soup. its definitely about butterflies and arthropods trust me

[@vlinderXXI]

I literally asked myself about this and now I see this upload. I love this channel

[@lollsazz]

I've heard about the "caterpillar soup" many times, but when watching an actual caterpillar transform, I thought that this definitely does NOT look like a soup, and either some people have a weird definition of "liquify", or something is quite wrong about the "soup" explanation.... my 2 year old is very interested in watching caterpillars metamorphose - now I'll make sure to tell her about the REAL way they do it 😊

[@ThatReplyGuy]

The Anti-Hero reference did not go unnoticed.

[@nlbuescher]

You know it

[@Brambrew]

Tldr: the caterpillar turns into a production line, only retaining basic vital organs as the rest of the body turns into liquefied mini-factories, each "factory" tasked with manufacturing a different part - legs, wings, eyes, etc. Then all the parts are assembled together and voilá, butterfly! And somehow, they can RETAIN MEMORIES after this process, remembering information from when they were a caterpillar!

[@suruxstrawde8322]

Well yeah the brain clearly doesn’t change much at all in the process just by the fact that’s true at all.

[@WAMTAT]

I've always wondered about this. Thank you for making this video

[@naturalcauses8768]

2:00 - 2:03 "It's me, hi, I'm some people, it's me" sound awfully similar to "It's me, hi, I'm the problem it's me"

[@cadrenadams9109]

I literally googled this yesterday and got distracted before I could find out the process 😂😂😂 this video is just what I needed

[@edsaurus1419]

Have you tried joining nebula? It’s a streaming platform like KZbin but it was made by a bunch of educational youtubers without an algorithm I think you might fit in quite well I really enjoy the channel thanks for the information joe!

[@VirtuousCreature]

Fascinating video! Though, cicadas go through INCOMPLETE metamorphosis. I loved collecting their shed skins as a kid! Lol

[@eham757]

Thanks for the video, finally it answered something I wanted to know for sooo long

[@Angel-Kitten]

It was very interesting to look inside the cocoon, thank you. I never thought that magic happens there. I was about right in imagining that a caterpillar grows new limbs while it is in a sleep-like state.

[@JHaven-lg7lj]

Oh my gosh, that’s one of my favorite books - it came out when I was 3, and my grandmother got it right away 😄

[@UnintentionalSubmarine]

It is a very fascinating thing. It has been weirding us out, probably since we began to think about things abstractly. But while the various forms of complete metamorphosis are all very interesting, I have always considered the incomplete metamorphosis to be much more curious. Take the larva of a dragonfly. While not as completely different as a larva is to a butterfly, it is still remarkably different from the adult animal. But one day it simply says "I'll go up that talk and shed my skin and then fly away." As in for a while a fully adult dragonfly was running/swimming around in an insect version of an encounter suit. That has got to be among the most weird things. And yes, I did notice the part about the proto-wings in the larva. And that is probably connected to the dragonfly approach.

[@Fab-n-dabKev]

This makes alot of sense. The pupa builds up a nice hardy molt to rest in while it's thin new body, like a crab in its soft delicate state, hardens up a bit.

[@martinezee4704]

Great episode! Well done 😂

[@kittylynx8911]

Love this!! Thank you ❤❤❤

[@FreedomDaveX]

It’s even wilder that many insects have such brief adult stages while spending most of their lives in their larval stages.

[@ShadareaRapt]

that hurt my heart to see the little wing separated from the caterpillar. interesting to see but heartbreaking too.

[@pirobot668beta]

Zebra finches are a tiny bird that does this 'soupy' trick twice a year, but only for parts of its brain! Part of the year, their brain is patterned to be champion singers and mimics. The other part of the year, they can navigate like nobodies business. But their 'flying brain' and 'singing brain' are very different in structure, appearance and purpose. Just like butterflies undergoing metamorphosis, most of the Finches brain 'melts' into a soupy consistency, and after a few days it reforms into the other brain. They retain knowledge from previous cycles: songs, social groups, feeding areas, nesting sites. While their brains are soupy, the Finches don't do much but eat and groom themselves. Strangely, injuries to the flying brain are absent in the singing brain and vice-versa! Weirder still, injuries that occur to the transitional brain usually fade away and heal without a trace. I worked at University with a lab doing research on the Finches 'healing' ability. They were looking at the melting/reforming mechanism as a means to heal brain lesions in people.

[@thefryingpan__]

I was shocked when I found out about this during one of my random searching this up sessions. I was even taught about the soup stage!

[@walmirneto3728]

I actually feel validated that Joe pronounces the e in winged when just the other day I was corrected for doing just that.

[@ForestFire369]

I think they have slightly different meanings

[@tim40gabby25]

What a wonderfully informative video. Well done. Old uk duffer here :)

[@OlShaky]

Omg!! Joe I haven't seen that caterpillar book in years. Nostalgic

[@acuddlyheadcrab]

I just realized something about Chrono Trigger, and it's that the earth was Lavos' leaf and he was just the caterpillar. what a dark story setting

[@glasshalffull2930]

Everybody knows about the difficulties honey bees have had with their colonies collapsing, but did you know the monarch butterfly featured in the video is also having a decline in their population. Scientists believe it is a combination of factors: loss of habitat, food source, insecticides, climate change, etc. If you want to help the monarch, the easiest way is to plant milk weed (only plant the female monarch will lay eggs on and the caterpillar will eat). Most local nurseries carry the plants, but you can also get seeds. It’s an early Spring activity. They can also point you to flowering plants that the monarchs like. Plant these and the monarch’s will come. If you want to really get into raising monarchs, there is an excellent series of KZbin videos entitled Mr Lund Science Monarch.

[@Erufailon42]

11:44 Correction: Cicadas are actually hemipterans and have partial metamorphosis like the rest of their order.

[@Khyranleander]

Have to wonder if it's also about metabolic costs & vulnerabilities. Live young is resource intense while making the bearer weaker/clumsier; eggs defer the vulnerability more to the young & lets bearers defend better. Larva, tho, are a cheap build layable in job lots that can collect their own resources before they re-gestate into full adult form.

[@CarlosBunn]

Most insects go from larva to the final form, but somehow butterflies have a better PR

[@Manojspidey18]

Why children books doesn’t have these stages explained because i think they still don’t have the age to understand that deeply.

[@xpndblhero5170]

I was the teachers choice for "growing" the Monarch Butterflies for 4 years in elementary school and it was my favorite time of year.... We released probably 400 over all the different classes that did it. 😁🦋❤

[@JohnHoranzy]

Thank you for explaining this mystery. It is not two different types of creatures. The butterfly is part of the larva to begin with.

[@DickVanWrinkle]

My favorite KZbin channel. Thanks Joe and team. I don’t mean to sound greedy, but it would be awesome to see you more often

[@maxdon2001]

Great video!

[@NewMessage]

And here I thought the transformation my wife goes through before we go out was miraculous.

[@MaGioZal]

We terrestrial vertebrates go through a kind of “metamorphosis” too, but as embryos inside eggs or wombs instead of external larval forms.

[@KyubiBubi]

Ontogenesis is not that special, though, insects have it, too

[@SoulDelSol]

They taught us in 80s/90s in school that caterpillar turns to bug soup in chrysalis and then reorganizing and forms a butterfly. Can't believe it

[@Pengalen]

"If the caterpillar doesn't turn into soup, what does it do?"

[@eileengannon5946]

This is SO COOL! I also thought they went from goo to butterflies. Wonderful!

[@omnipresentrose1850]

Not really related to the vid but I can’t believe that it’s been over 6 years since I first found this channel as a kid. I started watching it’s okay to be smart in primary school and I’m watching be smart in high school

[@crystaldragon471]

I kind of felt sad watching this video. I grew up in Arizona and remember seeing monarchs in the thousands every year. 20+ years later, i rarely see monarchs here, and it's usually only one or two when i do see them. I guess what got me is thinking about the struggle to survive for their species. Knowing how limited their allowed food sources are makes it hard for the caterpillars to survive. Agriculture and cities are virtually sterilized, and their preferred food sources are overgrazed. Our way of life as a global unit has completely changed the web of life on our planet, and such a small thing as the flap of a butterfly's wings can allegedly cause a hurricane somewhere else in the world. Point being, we should all consider individually and collectively how much we are willing to sacrifice for the love of life and all that is whole and perfect and beautiful.

[@badbiker666]

OK. Yup. I totally bought into the story that butterfly larva liquify inside the pupa/chrysalis and the various pre-butterfly bits (now I know they're called imaginal discs) migrate around the muck and get cemented in place and grow into their designated body part. Now I know the truth. That old story wasn't too far off, though. Just some of the details were left as, "and then a thing happens" and now I know what those things are. This was one of my favorite Be Smart videos ever!