How the Starfish Got Its Arms

Thank you to Blinkist for supporting PBS. For more information and trial go to www.blinkist.com/pbseons
The story of how the starfish got its arms reminds us that even animals that might be familiar to us today can have incredibly deep histories - ones that stretch back almost half a billion years.
Thanks to Franz Anthony for the incredible Echinoderm illustrations featured throughout this episode: franzanth.com/ And thanks to Dr. Sarah Sheffield, Dr. Imran Rahman, and Dr. Aaron Hunter for advising on the artwork.
Produced by Complexly for PBS Digital Studios
Super special thanks to the following Patreon patrons for helping make Eons possible:
Steve Descoteaux, William Craig II, Tracey, Hizrihel Alkawa, James Dowling-Healey, District Fungus Mycology, Frans Balendong, Irene Wood, Derek Helling, Margaret Luby, WilCatRhClPPh33, Mark Talbott-Williams, Elizabeth Baker, Eddy, Angel Alchin, Julie Cohen, salsablog.band, Sean C. Kennedy, Eric Roberto Rodriguez, Hillary Ryde-Collins, Frida, Yu Mei, Dan Ritter, faxo, Jayme Coyle, Gary Walker, Patrick Wells, Aziza Ashling, GrowingViolet, Stephanie Tan, Nick Ryhajlo, John Pollock, Ben Cooper, Leonid, Robert Noah, Matt Parker, Heathe Kyle Yeakley, Jerrit Erickson, Anton Bryl, MissyElliottSmith, Zachary Spencer, Stefan Weber, Andrey, Ilya Murashov, Merri Snaidman, Gabriel Cortez, Marcus Lejon, Robert Arévalo, Todd Dittman, Betsy Radley, Anthony Callaghan, Philip Slingerland, John Vanek, Eric Vonk, Henrik Peteri, Jon Monteiro, James Bording, Miles Chaston, Michael McClellan, Jeff Graham, Daisuke Goto, Gregory Kintz, Chandler Bass, Tsee Lee, Robert Hill
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References: docs.google.com/document/d/1h...

[@TransSappho]

Fun fact: echinoderms and hemichordates are the closest phyla of life to chordates! You’re more closely related to a starfish than you are to an octopus

[@ancientswordrage]

Knew it

[@crunchylettuce]

And you’re…not? lol

[@ylhajee]

That's a cool way to put it! Really drives home how amazing it is that octopodes have evolved to be so intelligent even though species more closely related to us, like starfish, totally aren't.

[@greatgarnation2092]

@@ylhajee it also shows many examples of convergent evolution aswell like the eye in both cephalopods and vertebrates

[@felipeantonio1304]

patrick star is my cousin, makes sense similar in intelligence

[@walrus4046]

This episode of PBS Eons proves that video didn't kill the radial star

[@XD152awesomeness]

This needs more likes lol

[@hewystudio7832]

Someone give this person an award or something

[@abruemmer77]

Oh deer

[@Epupify]

Become a patron and submit this hahahaha

[@millicentduke6652]

*rimshot*

[@DeRien8]

Downward facing starfish sounds like the easiest yoga pose ever

[@OGbluetooth_]

Just lie flat on your face and you're done 😂

[@holothuroid9111]

But you have to get your mouth to the center. Good luck with that

[@Roboprogs]

Patrick: I’m on it, I got this one. You two go do your karate.

[@greensteve9307]

Pretty sure "starfish" is already slag for a sex position...

[@evilsharkey8954]

Corpse pose seems a little easier.

[@RevereShin]

"You bet Jurassic can" is ACTUALLY an amazing punchline.

[@luispablogonzalezv4522]

The best so far

[@OverTheVoids]

Most of the jokes they get are meh, but this one was golden.

[@timmmahhhh]

Definitely the best one so far!

[@kwakas4ever]

It cracked Kallie up for sure!!

[@origaminosferatu3357]

@@kwakas4ever i love how that joke completely destroyed her. Top notch dad joke.

[@AaronShenghao]

“Help! I had fallen and I can’t get up!… Hello?… right… I guess I will live like this them…”

[@LimeyLassen]

Starfish: "I need help" Evolution: "Do you want help?"

[@absalomdraconis]

Yeah, starfish probably started with sea lilies adapting to survive long enough to regrow their stalk, and then optimizing around that route.

[@gavinoaw]

"Guys, seriously, I'm getting really hungry.... hello, anybody?.... hmm, actually this floor is kinda tasty..."

[@zacrintoul]

I feel like this might have started as a new feeding method. Essentially face planting into something tasty. Or something that is producing the filter feeding things it finds tasty before evolving into just feeding on the actual item itself. I'm picturing like a large decaying flesh item.

[@MargoMB19]

I love how this channel is constantly asking/answering questions I would never even think to ask. How starfish got their arms, did giant sloths poop themselves to death, how walruses got their tusks... One of my all-time favorite Eons videos is the one asking why things keep evolving into crabs.

[@brain_tonic]

🦀 Crab is inevitable 🦀

[@Tinyvalkyrie410]

Oh man I forgot I never watched that crab one to the end because I got interrupted by a puking cat. Thanks for the reminder, I’m definitely rewatching that one after this one

[@darkartsleather5586]

@@Tinyvalkyrie410 Thank you for the reminder. I watched the crab one full through and forgot that my cat was puking.

[@raymondmejias8071]

Yes...mine too..that was so interesting. 👍

[@raymondmejias8071]

@@Tinyvalkyrie410 😂😂😂😂🙀🙀🙀🙀🤮🤮🤮🤮

[@TimeBucks]

Kallie's laugh and inability to to say it without breaking make the video even better.

[@ahmedtuama9979]

Nice

[@deadandmoved]

True, but shut up company

[@VikSun14618]

Ooooo check mark

[@praetorianguard261]

@@deadandmoved This is youtube not twitter

[@jasonfrye4669]

What makes certain echinoderms even cooler is that some are re-evolving bilateral symmetry like the sea pig.

[@mimisezlol]

I thought they're still bilaterians, just not as adults. Yknow, the way tunicates are chordates, even thought they loose their chords as adults

[@seanhall5385]

​@@mimisezlol easier to visualize if you add the reference axis. The 'face' of bilateral animal evolved pentalateral symmetry while becoming the dominate feature.... Ulitimatly core body plan at adult stage

[@Whymust898]

I’d love an episode on the evolution of monotremes (platypuses and echidnas). I know they’re the old mammals, and it’d be fascinating to see the fossil record we have of them and our split from them

[@l.mcmanus3983]

I remember being so excited when the genome of the platypus was sequenced and released about 15 years ago. It’s a fascinating paper the read because the genome contains such an odd mix of genes, quite mirroring their exterior. I second a video about monotremes! 😁

[@KlavierMenn]

they are Yinotherians. when the ancestrals of the platypuses were crawling about there were no T rexes yet

[@reyvilla8501]

All platypi are bi

[@blada0017]

@@l.mcmanus3983 how can I find this paper? Thank you for the answer.

[@JimJamTheAdmin]

@@reyvilla8501 based

[@YourPhysicsSimulator]

3:52 "If you're just going to sit still, capture food and not move around, the radial body plan may help you better access food in 360°" *Ahhh I sometimes wish I was a starfish* ...

[@brain_tonic]

Don't worry, you can still adopt a radial body plan if you try hard enough.

[@brain_tonic]

@@capturedflame I know, it was just a joke mate...

[@RadeticDaniel]

@@capturedflame well.... we usually say radial when meaning strictly planar radial or non-spherical radial, but if you want to be nitty-picky... the so called radial is only looking at a cross-section, while the spherical keeps the radius all around in 3D

[@mrjones2721]

The main problems are that 1. no eyes makes watching KZbin hard, and 2. your chips will get soggy.

[@sycanide]

"how the starfish got its arms" patrick: * *nervous sweating* *

[@akumaking1]

*Starro wants to know your location *

[@abeezekielmonteagudo607]

Why so nervous Patrick? Nothing is going to happen to you.

[@rl9217]

Evolution: “Ok, so there’s new competition for niches, so here’s what we’re going to do. Your gonna evolve multiple arms to help you feed and survive-…are you even listening to me?” Starfish: “LEEDLE LEEDLE LEE-”

[@PremierCCGuyMMXVI]

I died lol 😂

[@marliewarhaft]

I think it should be unanimously agreed upon that this did in fact happen

[@crapsound]

I read it in his voice. I couldn't help it. 😁

[@Mini_Squatch]

im afraid i dont get the joke

[@Kobolds_in_a_trenchcoat]

@@Mini_Squatch SpongeBob i think but I'm not entirely sure I get it myself.

[@jessicaclark7130]

When an Eons episode asks “Why…?” The answer is almost always “The environment changed” :) evolution is cool

[@dhutch71]

Yes... Earth's environments change constantly due to plate tectonics... the very slow movement of crustal plates driven by the internal heat engine of the inner Earth cause seas to shoal, to deepen, to change salinity, to dry up, etc. Of course, it takes a very long time.... Geologic Time.... to do these things.

[@chubbrock659]

It’s weird how climate changed even before humans existed, and now we think we can change it with a tax.

[@WanderTheNomad]

@@chubbrock659 Not that weird considering the time scales of change. If we can do as much change to the climate unintentionally in just a few hundred years as other natural processes can do in millions of years, it's not a far cry to think we could do some *massive* change _intentionally._

[@ozarkecologies]

@@chubbrock659 "We think we can change it with a tax" we already have changed it with carbon emissions

[@rolfs2165]

The interesting part is how the environment changed and how those changes affected the animals over time.

[@gwenpoole1071]

Her laughing that hard was icing on an already "stellar" video

[@bbirda1287]

The fact that their larva are bilaterally symmetrical and they become adults by one half splitting into 5 parts while the other just drops away, wow.

[@shawon265]

: Is this an Echinoderm? : No, this is Patrick.

[@fodetoure1576]

“I was happy floating and looking at the stars” 🌟

[@TheBlueB0mber]

“Starfish is common slang for a butt-hole…do you believe there is a connection?”

[@razvanmantu]

We need to up your comment. Had to search a lot for the Starro reference.

[@pagerewrite]

I'm still sad 😭

[@FujiAppul]

@@pagerewrite Me too buddy. Me too. ;-;

[@demonatemu]

other animals: i will evolve to move in one direction and thus have bilateral symmetry starfishes: hgjkfdkfhgjhk

[@achillobator-xs1zq]

Me: WHY CAN'T YOU BE NORMAL!?!?! Starfish: **incoherent screeching**

[@Platypus2175]

Isn’t multiple starfish just starfish not starfishes

[@Archgeek0]

@@Platypus2175 Yes, but starfishes is used when discussing multiple _types_ of starfish.

[@Noname-67]

Starfish: *Reject bilateral symmetry, return to radial*

[@impendio]

Whenever I’m reading or watching something about Echinoderms, it always boggles my mind that they are by far the largest Phylum with absolutely no _freshwater_ members! I’ve always wondered how or why it is so, almost every other major Phyla has evolved either freshwater and/or terrestrial forms independently, and often multiple times and back into both aquatic and/or marine forms. There’s obvious reasons as to why we never got terrestrial _sponges or cnidarians,_ but that didn’t really stopped mollusks from trying time and time again, but how hard could’ve been for Echinoderms to evolve into freshwater? Maybe something about their hydrostatic inner skeletons or something? We’ll never know for sure…

[@drsharkboy6568]

Maybe their tube feet can’t support their weight very well on land?

[@l.mcmanus3983]

Perhaps it has to do with things necessary to their anatomy, or maybe it’s just that they found their own little niche and flourish in it well enough to never feel the pressure to evolve for life not in the ocean.

[@l.mcmanus3983]

Or perhaps some did evolve at some point but were not very successful for whatever reason. With all the extinction events in earth’s history, I continue to be amazed life even made it to our present day. 😂

[@AlienRelics]

@@drsharkboy6568 Freshwater, not dry land.

[@drsharkboy6568]

@@AlienRelics perhaps freshwater lacks a certain mineral that they use to build their skeletal structure?

[@jjjjjjjjjjjjaime]

This show makes me happy in so many ways I can’t even tell

[@Xnaut314]

One very obscure fact about echinoderms and similarly related genera is that their early cellular development from fertilized zygote to blastula is deuterostome rather than protostome, where the first few cellular divisions remain fully undifferentiated genetically rather than predetermined based on their orientation to other cells. To explain it simply, if you removed one cell from a protostome body when it's only fours cells big the two new bodies won't form properly and will die since both are already developmentally incomplete, but a deuterostome that is separated at the same time will develop into two fully normal genetic clones of each other. That's how we know that echinoderms and chordates like all vertebrates are more closely related to each other than all other animals, but it's also strange that protostomes have a vastly greater biodiversity of species overall, including genera like arthropods, molluscs, and the multitude of worm groups. Deuterostomes on the other hand, while much more limited in the total number of species seem to have a greater proportion of their species that are relatively large-bodied, weighing at least one kilogram while the vast majority of protostome species weigh less than that. Why that dymanic exists, both genetically and morphologically, and why the biosphere of the tree of life is oriented as it is a complete mystery to biology and has always fascinated me despite the fact that practically no one ever talks about it.

[@absalomdraconis]

The early differentiation probably either causes fragility to interfertility (faster speciation), or simplifies organization (somewhat akin to what distinguishes our branch from bacteria & archaea in the first place).

[@musaran2]

This is the kind of mystery I like. Got any link about it ?

[@twistedtachyon5877]

Well, add me to the club. That IS fascinating, and I have never heard anyone talk about any of it.

[@cowboykelly6590]

Personally, I think : their fun to look at .

[@johannageisel5390]

Wait, does that mean that when you split a human embryo into two when it's only 4 cells old, you would get two human clones of each other?

[@spiraldown2710]

When I was very little I used to (carefully) examine my mum’s seahorse and starfish skeletons. Only primus sea of cheese album cover fascinated me as much at the time Life before inter webs. This episode weirdly took me back, thank you

[@radRadiolarian]

thank you for introducing me to new (to me) music!

[@geodkyt]

Why do I feel like this script was originally written for Blake, the Master of Dad Jokes? 😆

[@Fitten06]

Callie writes those in for him 😉

[@AifDaimon]

@@Fitten06 🤣🤣🤣🤣🤣

[@CGaboL]

I came here to for the starfish, but learned that the Pokémon Lileep is more an echinoderm than it is a cnidarian. It has inspiration from both, but the main one is ancient sea lillies.

[@vreaum]

that's cool!

[@PaulTengco]

As Lileep is a fossil pokemon, this makes so much sense.

[@sephikong8323]

And it still is not a plant ........ freaking grass type

[@frogboyclips]

@@sephikong8323 well lillie's are a name for a plant so it's probably that

[@ScionStorm1]

@@sephikong8323 Slugs aren't usually made of lava either.

[@PremierCCGuyMMXVI]

“How the starfish got it’s arms” *NO THIS IS PATRICK*

[@mimikiryuu]

So...ur not a Crusty Crab? 🦀

[@SveninColorado]

"You Bet Jurassic Can".... I am still laughing! Thank you for bringing these wonder filled presentations. What you all do is true science...raising as many, or more, questions as you thoughtfully and thoroughly seek answers. Eons is truly a breath of fresh air for this old man. I look forward to each new episode.

[@AifDaimon]

wait, timestamp?!

[@danielwolf4935]

@@AifDaimon it’s near the end of the video where she reads a joke from one of the patrons on patreon

[@727Phoenix]

This video helped me understand the evolutionary history of the Elder Things, a race of aliens written about by H.P. Lovecraft. Thanks!

[@dennisdanner4273]

My opinion is that they are highly evolved descedants of Sea Cucumbers

[@joshuahadams]

The Elder things are _old_ and likely the source of life on earth. According to “At the Mountains of Madness” the came to Earth from the stars nearly a billion years ago, after the formation of the moon and oceans. “The persistence with which the Old Ones survived various geologic changes and convulsions of the earth’s crust was little short of miraculous. Though few or none of their first cities seem to have remained beyond the Archaean age, there was no interruption in their civilisation or in the transmission of their records. Their original place of advent to the planet was the Antarctic Ocean, and it is likely that they came not long after the matter forming the moon was wrenched from the neighbouring South Pacific. According to one of the sculptured maps, the whole globe was then under water, with stone cities scattered farther and farther from the antarctic as aeons passed. Another map shews a vast bulk of dry land around the south pole, where it is evident that some of the beings made experimental settlements though their main centres were transferred to the nearest sea-bottom. Later maps, which display this land mass as cracking and drifting, and sending certain detached parts northward, uphold in a striking way the theories of continental drift lately advanced by Taylor, Wegener, and Joly.” - ‘At the Mountains of Madness’, ch.7

[@727Phoenix]

Of all the creations of H.P. Lovecraft, the Elder Things have always been my favorite. Not sure why.

[@deathsyth8888]

SpongeBob: Patrick! Where did you get those arms? Patrick: Uh... I don't know.

[@treering8228]

7:25 is fascinating! The one in the upper middle left looks like a nasturtium seed and the top middle one is reminiscent of fungus that grows on trees, not to mention the obvious clam shaped one. The rest are so otherworldly and foreign. Wow, just, wow!

[@impishDullahan]

Kallie not being able to keep a straight enough face to deliver the punchline made my day.

[@djbenje4019]

This narrator is a really excellent communicator. Pleasant voice, tone, articulation, and energy.

[@rensnestworks4183]

My favorite episode just because of the pun at the end, her reaction made me lol

[@prod1gy305]

Her laugh is really cute also

[@drswag0076]

is this a starfish diversification? no, this is Patrick

[@bluedragon219123]

So Starfish are basically the real life version of the "This is fine" meme since they evolved from a top facing animal that basically fell over and evolved around that new position. :)

[@colliscarlitobrazil]

That stalkless feather star looks so crazy it's amazing 🤯

[@ShikiKiryu]

Ahh so those Crinoids are what Lileep/Cradily from Pokemon are based on...they're my fav fossil creature in the series, interesting to see their real-life inspirations and what they were like :o

[@impendio]

Yep, and anorith and armaldo are anomalocarids

[@ShikiKiryu]

@@impendio Yeah I recognised Anorith's inspiration pretty easily as I remembered watching Walking With Monsters as a kid around the same time as RSE came out, and I recognised all the other fossil inspirations but Lileep/Cradily was never sure exactly...knew was a plant but didnt know what. Its interesting!

[@eomguel9017]

Finally! Feels like it's been Eons since the last Eons episode!

[@stephenjohn2131]

You know it's a good time when PBS uploads!

[@theonebman7581]

Eons: *uploads new video* Me: *Day just got better~*

[@Sausketo]

So what you're saying is, that all starfish are left handed?

[@michaelblacktree]

Haha, you beat me to it.

[@Simon-np8bt]

More like left bodied

[@jim1550]

"upward pointing spines" The Lego Fish

[@skyflaks6380]

A man has fallen into a river in starfish city

[@rogaineablar5608]

More important about the hydraulic tube feet is that they're strong enough to open bivalves.

[@Leomoon101]

Patrick: I wasn't always the starfish you see today...

[@chekeichan]

*faceplants* Hey this actually works out

[@romefromiris7424]

Babe wake up new pbs eons just dropped

[@Erinselysion]

All of these animals are so beautiful! This episode is super interesting, nature is so amazing

[@Hannah_Em]

Hecc yeah, a new Eons episode is just what I need to cheer me up stuck in hospital recovering from surgery! Thank you, Eons team! 😊

[@mho...]

Imagine that "holy sh!t" moment, when the first of them realized that there is waay more food below them, then in the water above! time to move that mouth to the underside & move around 😏

[@sheepboy2560]

STARRO THE CONQUEROR brought starfish on earth

[@animalpeeps]

The evolution of moles and other fossorial animals could be a fun thing! Their humerus bones are so fascinating! The joke was also so good! LOL

[@romankozak8728]

Kudos for doing an episode about something that is not a vertebrate, arthropod or mollusc. There are so many biota out there that we rarely hear about.

[@Alusnovalotus]

Patric Star: when in doubt, radials out ⭐️

[@keksidy]

Cool, but when are we getting the episode on how the emperor got his groove back?

[@Katiethewizard]

Perfect timing! I've been watching the EVNautilus ocean expedition videos to go to sleep for the past week!

[@ambulocetusnatans]

At 8:52 No don't go that way, little Hermit Crab!

[@Ubiquitous111]

Finally, another video! I wait with bated breath in between each upload. Seen all of them so far, can’t get enough! Thanks for the awesome content, Eons!! 💜

[@seedhillbruisermusic7939]

fascinating, and any footage of feather-stars swimming is much appreciated. how amazing they are!

[@KimberlyGreen]

5 may be ok for starfish, but hexagons are the bestagons.

[@robotechgunpod]

Found the CGP Grey fan. Nice to see you out in the wild, friend!

[@KimberlyGreen]

@@robotechgunpod {friendly waving} And a smiling hello to you too.

[@dirtymagic29]

I braved the comments for a Hexagon reference...and I wasn't disappointed.

[@naveerakhan9622]

Kallie's laugh at the end gave me life 😆 that's a good joke

[@iansteelmatheson]

that's amazing that you're doing this video today. I just had my first day of classes in a technical program called Environmental & Wildlife Management, and my first class was a Biology lab in which we used microscopes to look at baby starfish!

[@tiaxanderson9725]

Wait, so starfish have *FIVE* left feet?

[@fleachamberlain1905]

Very cool. Seastars and their relatives are so interesting.

[@luizaneves6030]

Just yesterday i was looking for videos about evolution in echinoderms! I love this channel, great content, amazing explanation and illustration! Please keep up the good work!!!

[@Scarlet_Soul]

A new type of arms race

[@leetakamiya]

Or an old type of arms race.

[@MrLouisbro]

The original arms race

[@ldbarthel]

I recall in Piers Anthony's _Macroscope_, our evolutionary relationship to starfish was a story point. (Starry point? Maybe take it up with your brothers and seastars...)

[@CarlytheWolf23]

My dad owns a serpent seastar, which I will say even though it's been a couple years it still is bizarre watching it move around lol Also nice vid again!

[@sewisinc.4545]

Great and interesting video and probably one of the top 5 even top 3 jokes ever told here. Kallie's laugh and inability to to say it without breaking make it even better.

[@mariothibau1070]

Amazing video! i love when PBS makes videos on the Cambrian and Ediacaran fauna.

[@squireob]

Suggestion: For timeline illustrations, you may want to have a gap marking the time between the prior event and the one currently being described. I would find that helpful.

[@MrFossil367ab45gfyth]

Basically, a crinoid got tired of feeding face up and it was like "You know what, screw this!" and then it put it's face down on the ground.

[@dennisdanner4273]

The crinoid was mobbed by its fellow crinoids and gave on being a crinoid but turned out very successfull

[@MacDelta]

The Artists that make these drawings from the fossils are amazing.

[@OGbluetooth_]

Eons is by far my favorite channel, I'm hyped for a new video every week and the days in between always seem so long 😂

[@leociresi4292]

The real Patrick Star Show!

[@nathanielbrown5148]

Absolutely favorite channel. Would love an episode on how Arthropods colonized land.

[@jimspace3000]

Beautiful video, and loved the LOL at the end!

[@theresacotty8214]

The joke at the end about knocked her out! Lol! Loved that part!

[@MrPenguinLife]

I find it odd that there was no mention in the video about how modern starfish are incredibly hard to kill.

[@lightreign8021]

There’s a wasting disease that does a great job of it in the Pacific Northwest. 90% of sea stars have died. Surprised that didn’t make it in there

[@cyberbrunk]

That was such a genuine laugh at the end, I love it

[@Rose-yx6jq]

How did I not know there was a new video. I am having a happy surprise.

[@Neenerella333]

I read this comment in Flula Borg's voice and accent.

[@aneweliseonlife]

Things I didn’t know I needed to know

[@selenaichtis6762]

My first time being early for a Eons video!

[@t0mn8r35]

This one was very interesting. Thank you!

[@hieutruong4519]

9:35 "So as odd as the starfish body plan seems..." I see what you did there, Eon :)))))

[@ooraculo223]

The starfishes survived the great dying and the extinction of dinosaurs. I hope they survive the humans too.

[@bunstructors8591]

Since one side of the body got absorbed and the other side became radially symmetrical, it means that they turned on the side first before flipping around?

[@absalomdraconis]

Perhaps the other side develops into the stalk of sea lillies?

[@johnmarkarroz4111]

Always love your videos!! Keep up the amazing and educational topics! 😍😍😍

[@Cashdummy]

fascinating, just fascinating. Thank you

[@jamminjamie1]

I love the indigenous recognition at the end!

[@mariosbrother6845]

after watching the suicide squad i'll never look at starfish the same way again

[@noahblaine9793]

I have found many starfish looking fossils in Mississippian age rock. I had no idea they were so intresting.

[@hemberger91]

Grew up on PBS. Now I can watch on KZbin. This is great.

[@PaulPaulPaulson]

We have bilateral symmetry, but our internal organs aren't. Is it the same for starfish?

[@LuinTathren]

Kallie, you are so cute! I love your videos!

[@markoroyan2170]

GREATEST joke/host reaction yet. Love that it caught her so off guard and her laugh is totes adorbs!

[@robertdorsey9631]

She is so much fun! I would never ever watch this type of video in the past. What a 'star' in the making!

[@mascadadelpantion8018]

I'm a simple man I see PBS I click video and hit like 🤗💯

[@FanUpFaker]

How do I never think about things like starfish once didn't have arms

[@kenbee1957]

Alternative title: How the Starfish became nom nom

[@MattHughes26]

Thanks Eons, loved this episode. I've always been intrigued about bilateral and radial symmetry since reading 'The Mystery of Metamorphosis'. I'd love it if you could do an episode looking at what has always been a head-scratcher for me and that's how are adult sea squirts radially symmetrical but their larval form at bilaterally symmetrical?! I've heard various theories, including one of hybridisation during the Cambrian but if you could shed any more light on this peculiarity I can finally put my mind to rest!

[@Scifinando82]

So you did sponges, squids, crabs and now star fish... so squirrels are next, right?

[@matthewwelsh294]

SpongeBob 😂😂