How the Squid Lost Its Shell

Published on Apr 17, 2018
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The ancestors of modern, squishy cephalopods like the octopus and the squid all had shells. In ancient times, their shell was their greatest asset but it eventually proved to be their biggest weakness.
Special thanks to Franz Anthony for the beautiful cephalopod reconstructions. You can see more of Franz's tremendous work at
And thanks as always to Nobumichi Tamura for allowing us to use his wonderful paleoart:
Produced in collaboration with PBS Digital Studios:
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  • They lost their shells and we got rid of our monkey ears...

  • brief yet comprehensive and informative just what I like..

  • I like those animals

  • Can we PLEASE have Neil DeGrasse Tyson co-host an episode on the astrological events that transpired at the time of the Cretaceous-Paleocene Extinction Event???????????????????? That is perhaps the only thing that would make this channel better, seriously you guys rock! (((:

  • The episode's counter part is called how turtles got their shells.

  • It looks like a funny wizard hat

  • it is OCTOPI!!!!!!!!

  • Every Species is trying to get on top of the food chain. :3 that's where we don't wanna lose

  • Ey, how could we know if an ancient non-shelled mollusc ever existed? I mean, is it even going to become a focile? Can we be sure that ALL ancient molluscs had sells?

  • wtf it had a shell

  • When and why did humans lose their fur (to become “ naked apes”) ?

  • Excellent video very informative. And not a single name mispronounced, see you can do it America!

  • this channel is amazing!!! thanks for making this

  • Wait a minute, I know this guy... doesn’t he have another channel dedicated to history? I remember watching him when I was still in school.

  • I agree with comment below, freaking cool. - I wanna learn about EVERYTHING !

  • Its like a really big hat thats only possible to werar when youre underwater and gravity is quite light.

  • What about the shell between his eyes

  • Cthulhu’s garden gnomes

  • Did you just tell me that these organisms can choose to change their appearance and create or discard shells or features by choice?

  • How did scientist know that it looked like an upside down ice cream cone squid tho. I mean, squids dont have bones to show its structure

    • The shells would have fossilised like bone.

  • Octopuses @ 6:17 🤔 octopi 🤷‍♂️

  • Can someone please explain to me the actual gradual evelotion between one feature of an animal changing? Like was it a sudden generation of mollusks that could float from birth? Was it a handful who were then naturally selected to build a full generation? Did they figure out how to float over a lifespan and then those smart ones passed their genes on?

    • At first, there would have been a mollusc that had a shell that allowed them to become lighter. This would have given them an advantage as they could get farther and get more food in the water and not from bottomfeeding. These molluscs will reproduce and pass on their genes. Those with more advantageous genes, like becoming lighter and "floatier" from the shell, would have been passed down to offspring more. The not so advantageous molluscs woupd have died and not pass their genes. Eventually, they adapted to become more like the cephalopods you see in the vid.

  • that isn't a squid thats a wizard


  • honestly, your story is really nice to listen to (and also convincing) but it just doesn't make much sense......someone please explain the thing

  • i love science but i dont really believe this evolution theory.

  • How does this video have over 1K dislikes?

  • We are all four lobed fish. Food for thought.

  • Floaty bois should be brought back.

  • squidward evolution

  • I think Octopuses might be my favourite animals like, ever. I'd honestly love to learn more about them!

  • I thought hank worked with scishow

  • the plectronoceras is so cute. Lil buddy looks like he's wearing an ugly birthday hat I love him

  • Trypophobia warning

  • Early Cyler Baby

  • It’s insane, humans have only been around for 10,000 years MAX and yet we’ve drastically changed the world unlike any other of the billions of species that have popped in and out of existence. Makes me wonder if we’re just another species that will only stay for a blip of time, only for a couple thousand years. Then life will begin how it started yet again billions of years ago. I just kind of wish we weren’t so different sometimes. Maybe the universe is a never ending cycle and you just come back at random times throughout its cycle, becoming whatever available. But playing your part.

  • At 03:38 you say that sphooceras tried a different tactic...breaking the end off the did you come to that conclusion? It's not like they just popped into existence over night, right? arn't there any intermediate fossiles or something? It feels like you just state/assume things but I would like to know why and how this came to be...I could see why some people wouldn't just accept this (creationists). Me? I'm just a sceptic and really interested :)

  • I still don't get how the know such details about how they lived from a fossil


  • 6:10 The I.Shell, Think different

  • Not 20 feet long it’s 18 feel long dummy

  • It looks like a wizard

  • You forgot to talk about how they learned to life on land and began developing language living together in harmony with the until THE GREAT TURF WAR

  • Clickbait: I came for the African folktale.

  • Since they evolved and started to float is it possible that they will be able to float out of the water U.U

  • Your big thinking words confuse me

  • Hank! What are you doing here?

  • He looks like iDubz

  • He said octopus's.... Isn't it octopi ??

  • I wanna know in the extinction that killed the dinosaurs... how did the Avian dinosaurs survive?

  • I for one welcome our Cthulhu overlord... and I'd like to remind them as a youtube personality I could help them round up others to toil in their chanting chambers.

  • Isnt this the guy from crash course?

  • so the Squid lost it shell because the turtle stole it, that's my theory

  • God Hank is the best, Ps if you don't you know Hank works on another channel called SchiShow. You should really go check it out if you like l this.

  • i love to know where my calamari came from

  • ummm snails still keep their shells

  • Science... 🙌 🙏

  • They all look delicious 😋

  • Next up: How the Squid learned to walk on land and make ink guns.

  • it is all dependent on what is available. world space ship.

  • Mr. Hank Greene I wish you a very merry Chocolate and Mint season.

  • upside down icecream cones - cthulu flavored

  • That was pure poetry!

  • Bio-engineering at its finest.

  • Very interesting video, thank you. Can you please make a video about the species that remain rather unchanged over millions of years and why they remain like this, slower mutation rates? very successful form? are they actually changing and the other forms disappeared?

  • Crocodile ...... Salt water crocodile please

  • Someone needs to add Splatoon sound effects to this.

  • That shows intelligence and flexibility are more successful than shells. Yet many people in todays society think literally building walls around them will solve the problems.

  • Thanks for this explanation of the fascinating evoltion of Cephalopods for nerds. PBS is a wonderful educational channel.

  • Squid and octopus are some of the most intelligentanimals on this earth only second to creatures like dolphin, orcas, monkeys etc.

  • Interesting video , fucking annoying narrating.

  • What the shell🐚

  • Those are some big words for shell

  • This makes me question what if prehistoric animals still lived today???

  • Did he digivolved?

  • I'll let "cephalopods" go, but the few plurals for octopus are 'octopedes' 'octopods' and 'octopodidae'

  • Hank and Joe looks more like siblings than Hank and John

  • How did the chicken cross the road?

  • Hank, that's one disgusting ice cream cone.

  • This is a super interesting story. Great explanations

  • The history of calamari

  • What gas is in their shells and how they get it? I guess dissolved gas in ocean water or they create gas.

  • Merçi

  • can you make a vid about malware?

  • fantastic

  • I thought for sure they were going to pin this one on global warming too.

  • Fantastic, thank you!

  • Subbed!

  • you are a kid, you are a squid. great video, it helps a lot.

  • Boi you said "octopuses" and it's octopi.

    • It's both. And octopi is technically wrong anyway, since "octopus" comes from Greek and -i is a Latin plural.

  • Admit it It looks cute with a shell

  • Thank you for explicitly saying Non-avian dinosaurs

  • 3:48 this creature literally rebelled against it’s own design. Like “no I’m better off without this dumb shell the universe gave me, I’m gonna go ahead and bite it off”.

  • Calamari anyone?

  • How Squidward Tentacles became bald.

  • This was really interesting!

  • Great Evolutionary rendition! Thanks, I would love to see how you track the origins of the digestive system of humans and the evolution of the Human body, considering it has about 7-9% viral DNA, and that about 70% of our DNA can be traced from Acorn Worms(Please See Philippe Cousteau's, "The worm from whence we came") There are 2 relative species for us(the 'Krusty the Clown' looking one, and the one that looks like a our GI System(please see YT- "The Hungry Microbiome") . Also if you look at the physiology of the systems of our digestion such as the GALT around our intestines and in the Brain- the three layers between our brain and the Skull. It indicates a consensual, symbiotic, synergistic relationship that caused the cohabitation and awesome collaboration that makes us human. If you look at a chicken and a whale embryo they look pretty human for the first few of the earliest recognizable stages. Why and What was the Third Major critter that joined the party about 500 million years ago. Perhaps a Jelly Fish? They have the Identical Cochlear system that would be pretty impossible to develop independently. Thanks in advance, Cheers, peace and happy trails!

  • very informative video on cephalopod evolution :)

  • 7:07 what the hell is that

  • I greatly appreciate your list of references in the description. Thanks!