Chordates - CrashCourse Biology #24

[@mikeysrose]

I knew I'd found the perfect guy for me when I looked him straight in the eye and introduced myself as "A mammalian amniotic tetrapodal sarcopterygian osteichthyan gnathostomal vertebrate cranial cordate" and he looked back at me and said, "... Hey! Me too!"

[@courtneysteward7936]

I would love if you guys made an entire series on Zoology. These videos are so helpful when I'm studying.

[@JC-zx3bd]

yes courtney!!

[@robertelee3889]

Evolution is a hoax. Read your bible!

[@robertelee3889]

Everything this guy says are satanic atheistic lies. There is no such thing as chordates, vertebrates, or invertebrates. There are only humans, animals, plants, and God. The bible is 100% truth!

[@humanbeing6640]

@@robertelee3889 Omg man you gave me a good laugh 😂😂

[@kaitlyncarter5868]

@@robertelee3889 I really hope you're joking! 🙃

[@veilsariel5282]

Want a T-Shirt with "Hello, I am Mammalian amniotic tetropodal sarcopterygiian osteichthyan gnathostomal vertebrate cranial chordate"!

[@tomas2375]

You probably meant: "Mammalian amniotic tetrapodal sarcopterygian osteichthyan gnathostome vertebrate cranial chordate", not "Mammalian amniotic tetropodal sarcopterygiian osteichthyan gnathostomal vertebrate cranial chordate"!

[@jayparekh4080]

@@tomas2375 google suggestions be like

[@daniellin7425]

Yessir

[@Callum724]

when you look at the taxonomic name for humans at the end of the video and then you find out that this name was pioneered by one person carl von linnaeus you really do start to appreciate the genius of that man.

[@micahgruenwald9321]

* the genus of that man

[@WerAllFromHere132]

There are actually 5 common characteristics that all chordates share. The fifth one is the endostyle. It controls how quickly the body uses energy, makes proteins, and controls how sensitive the body is to other hormones. (Ex. our thyroid glands)

[@whitecharcoal10]

this is amazing. it is so nice to review this before my exam. i have all my questions answered. i couldn't thank you more for this. i am so grateful for this video.

[@Lexyan23]

This series makes me understand biology so much more than I ever did in school.

[@bridgetisadreamer]

I got strangely excited when you mentioned the hagfish. They fascinate me because they literally tie themselves in knots over where their next meal comes from. They secrete organic chemical then tie themselves around the carcasses of sea creatures. The chemicals and tightening body act like a kind of knife!! And they seem to absorb this meat through their skin and gills!! Its just so crazy and awesome :) Thanks for mentioning them Scishow!!

[@oluwatomiolanrewaju6456]

"Scarlett Johansson" This man was ahead of his time.

[@AdobadoFantastico]

She was definitely already hot 8 years ago.

[@jackdawmystery9408]

I have to rewatch these so many times since I'm terrible with names whether it's Hank Green or Cephalochordata.

[@ihh2921]

but dude, use the wikies

[@owenperez87]

why did I read that as cleopatra

[@raikespeare]

So we're a bipedal species in a tetrapedal superclass; I guess that means we stand out. SCIENCE PUUUUUUUUUUUUN

[@salmonsaladsandwich8161]

Tetrapodal refers to number of limbs. How you use them is irrelevant. Even snakes are technically tetrapods. The term for an animal that happens to use all four limbs for walking is quadrupedal.

[@eliascorrea8573]

heeeyyy gj

[@NoActuallyGo-KCUF-Yourself]

*appropriate amount of applause*

[@neq7141]

:-:

[@saniasingh4171]

I have ABSOLUTELY hated biology all these years at school and now, thanks to you, this is one of my favorite subjects. 😀 (final exams, first year of high school, and you've helped me a lot.) Thank you. :)

[@meghanpierce5375]

Hey, I just want to point out that there's two living coelacanth species- and they are both in the genus Latimeria. There's the West Indian Ocean coelacanth (Latimeria chalumnae) and the Indonesian coelacanth (Latimeria menadoensis).

[@Angelamica7253]

Using this to review for midterms c: It's honestly not that different from what the professor is covering, and y'all make it look interesting, so yay!

[@bdubbs1492]

Definitely one of my favorite CrashCourse Biology Episodes! Great job Hank and the rest of the CC team!

[@TheMindfr3ak]

what about endostyle? that's another characteristic of chordates

[@AllisonPiperjosephine]

Got an A on my test! THANK YOU CRASH COURSE

[@nasroafidi1837]

Hello

[@blutiga22]

This was amazing. Literally my entire quarter of Vertebrate Biology at UCLA in a nutshell!

[@kayla1558]

This helped a lot! I was struggling understanding these concepts in school, and I had a science exam. I understand the concept so much better now! Thanks!

[@cassiopeiayc8762]

u make me remember this subtopic by linking all the classes together thanks so much!

[@culturekate]

I.LOVE.THE.CHORDATES. Learning about them is my chocolate! Just remember though, it is a little wrong calling the chordates the most 'complex' who are we to judge, [even if they may seem that way to us]

[@thebeluvdtrex]

I caught a Coelacanth one time... in Animal Crossing.

[@MeanderingMeagan4]

Just got my AP Bio exam score - 5!! I can't help but think it's slightly because of these videos, even if he posted one that was all about one of the essay questions the night of the day of the test! I was livid when I saw it. Livid. But it all worked out, thanks Hank!

[@Olucatei]

That's something that has happened multiple times, as it is really, really useful. Basically you start out with a light sensitive patch of cells, which mainly tells you what time of day it is. But if a depression forms, it is possible to tell the direction of the light, which is slightly more useful. Selection gradually deepens the whole while restricting the entrance until you have a pin hole camera like that of the nautilus. Add a lens and a few other things and you're done.

[@FrancesBaconandEggs]

"One of them is designed for flying around, and being graceful and stuff." LOL! Hank, you win.

[@14KKnight]

this is fantastic! I love how everything is so connected.

[@undertheseathings]

Been watching you for years and I am so excited to say that the current University I attend in Australia often links to your videos. Thank you for always teaching such extraordinary things :).

[@davi.movement]

this does make me feel smarter... but it also makes me realize how lacking my own education has been. Thank you Hank (and John), for doing what the public schools are often not.

[@ALLIBOOWITHLOVE]

You just saved my Zoology grade, thank you so much!!!!

[@sarahh4389]

These videos are so helpful - I am a college level zoology student and these definitely help - I think you guys should make a video about asymmetrical cell division, as well as cell fate maps and stem cells - that would be amazing beneficial

[@keulron2290]

"There's actually some controversy between taxonomists.." When is there not?

[@Skippa1986]

I just started watching CC Biology and I already get the impression that the CC world history has a bigger budget. Animation! Music! A chair!

[@abhyarthanabehera4802]

you just summerized my whole chordates syllabus in 12 minutes....

[@anthropomorphisis]

I love that I can laugh while learning. Thanks, Hank and the Scishow crew!

[@frenchtehllama]

Hey, I'm having fun! I love reading these things. On one hand you have the religious zealot and on the other the non-religious zealot, and then outside you have the spectators who are, to extend a highly tenuous metaphor, placing metaphorical bets on the outcome. This is better than popcorn at the movies.

[@starsarahh]

love it! i got a couple of baptist friends who would argue heavily against the Osteichthyan part, that is, if they knew what it meant! Yay for bony fish!

[@vmphy]

Echinoderms (e.g. Starfish) share a recent common ancestor with chordates and are among their closest relatives. Both fall under deuterostomia, but echinoderms lack the notochord, dorsal nerve chord, post anal tall and pharyngeal slits that are characteristic of all chordates.

[@LeoLDA1]

I have a feeling that the book he reads is completely blank

[@KingCadmos]

Look. It is.

[@saniasingh4171]

King Cadmos It is. Completely. Blank.

[@crazytricksmore7121]

It is

[@TheHydeparkcorner]

Your channel is the most amazing channel here on youtube !

[@gabrielabigas2735]

love this guy, I learn so much more than in class

[@josiahklein70]

We are faamily! I've got all my chordates and me! (Correct me if I'm wrong.)

[@meepmerp1562]

+Josiah “The Philosopher In Green” Klein basically all of living things are related...

[@mathmatucla]

They are exceptional mammals, a yet-to-be-discovered level of awesome.

[@sazarod]

I was waiting for Hank to say, "unless you're a platypus."

[@mishka10ify]

mum walks into the room: " what are you doing?" me: being a mamalinathrodfgdrgg.... watching a video"

[@kimhong3033]

these videos are life savers! Thank you so so so so much! I just want to hug you all and thank you! but since I can't here's a virtual hug.. *Huuuuuuuuuuuuuuuuuuuuuuuug ❤️💙💜💛💚*

[@TremendousHeart]

Dear Hank, thanks for making videos about animal phyla when i was actually taking/failing my zoology course at school. Love, a sarcastic nerdfighter

[@HolyGoucky]

That name tag made by day, Really really amazing episode. It all makes so much sense now! *w*

[@thGothicHobbit]

8:46 "and getting those four feet onto land was really awesome" ...indeed. As Carl Sagan once so brilliantly put it, it was a "great, breath-taking adventure." :P

[@linathompson2519]

You are the best articulate folk I know thanks... ❤️ love your knowledge and enthusiasm

[@pg9ilta17c]

this videos will never cease to excite me

[@kcclontziv3056]

Hello, Im Mammalian amniotic tetropodal sarcopterygiian osteichthyan gnathostomal vertebrate cranial chordate, whats your name?

[@meepmerp1562]

+Ken Clontz Homo sapienz

[@comicarmy8766]

Yea the same wat u said

[@TheBuddsO]

crashcourse teaches 2 subjects, world history with John, and biology with Hank. Scishow is about science in general with only Hank. :)

[@JunohProductions]

I paused the video at 6:33 with the funniest face I have seen in a video in a long time. I love random moments like this.

[@KRAPYBARA84]

I was reading Rise and Reign of Mammals and it sparked my quest to know more about my fellow mammals. I slowed this video down because I am drunk and also I love pretending you are too! Cheers!!

[@CallMont]

HOW THIS DOESNT HAVE MORE VIEWS! awesome job! thanks so much for doing this ;)

[@MooMooMath]

I always learn something new with your videos. Thanks

[@Alchemydude667]

This brings back so many good memories of one of my course's a few years ago, Vertebrate Animal Biology. Such an interesting course.

[@selena8433]

These videos are perfect for those of us cramming for a bio final

[@rinaann]

Wow this is great! Thanks for helping me review this material and making me understand what the words actually mean.

[@paulavalbuena8298]

OMG! That last part was sooo FUNNY 😂😂😂 thanks for the info! It will help on my thrum only test! :)

[@CrazyPurpleLady]

I'm doing all this in college now, so this video is super helpful! Thanks Hank!

[@JaylaCucu]

I like that Crash Course and SciShow and such allow enough time to the viewers so that we can actually read the credits. And John says names outloud. I don't like that in most movies anymore, they just zip through the credits. If credit is earned somewhere, let it be given. As you do.

[@BloomWithYoo]

You just save my life T_T Thank You so much for making this video

[@hailvishnu]

I simply love that Dame Judy Dentch is listed as if she were a separate species of mammal!

[@OptimusSkiver]

I am proud of this insane lineage that we share, and I am proud to be a mammal who may have living cousins, extremely distant they may be, who are fish.

[@ianalvord3903]

Where does he get those book covers for the Bilo-ography?

[@NeonsStyleHD]

It's called a printer lol

[@ianalvord3903]

But it's plastic.

[@PlasmoX]

Ian Alvord it's called, production value!

[@sk8ercv]

Thank u for these videos on animals I have my biology final tomorrow and am just now watching these vids and just now inderstanding. Thanku thanku thanku!!!!

[@sarahlapotin8393]

I study evolutionary biology, particularly ichthyology, and every fish enthusiast I know has a coelacanth shirt.

[@14h3ndo]

IM IN UNI AND THE LECTURER TAKES 4 WEEKS EXPLAINING THIS VIDEO xD should i just give you £9000?

[@MarshallTheArtist]

Why are you paying that much for a single course?

[@faceman9507]

@@MarshallTheArtist Uni prices in the UK

[@Vincisomething]

@@MarshallTheArtist have you seen tuition costs 😭?

[@poonamvarshney7511]

Uni,? I have this for 9th grade.

[@thatweirdguywhostalkspeopl1908]

I pay abt £900

[@iLOVEpicklesBRO28]

I love watching these, especially in the summer. They keep me on my mental toes xD

[@RazorSharpClaws]

I love these videos despite not being a sciency kind of person. I was really surprised to not see a llama in here... but this video helped me understand a Mountain Goats song, so that's pretty cool!

[@bemoorfun]

I "get" science, that is why I love watching Hank Green's videos... I have watched every video he has available on youtube... yet I also learn from many other scientist and there is a lot more scientific proven data that is available... I look at all the facts

[@jufemonve]

Hank, great video...would you please explain whats the deal with the PLATYPUS

[@JC-zx3bd]

you're saving my grade in Bio... thank you!

[@drewdogggg1]

i love Sci-show. Even if i have no idea what he's talking about, it's still entertaining.

[@Natuurbescherming]

Nice, the biggest challenge with @crashcourse and @scishow is to develop subtitels in Dutch, so the children in Holland also can become awesome intelligent. Knowledge and humor is a stunning cocktail. I suppose there is also a challenge for the French and German public. Idea? Maybe it;s even possible to produce this in dutch? Best regards, Arnout-Jan Rossenaar

[@dftbachick1929]

2:12 When you said "nerve fibers" at first I thought you said nerdfighters. Carry on. :)

[@lisajade2961]

how is it fair that you can teach so much better than my uni lecturer that I am paying £9.25k for??? he explained this and genuinely I was so confused, but you made it so easy?

[@merrymachiavelli2041]

Are mammals really more complex than birds? Not to be unpatriotic to my taxonomic Class, of course.

[@merrymachiavelli2041]

He refers to mammals as a group as 'the most complex phylum'. Basically, are the traits that characterise modern mammals more complex than those than characterise modern birds? Picking a specific mammal or a specific bird isn't really the point, as I'm referring to traits all mammals and all birds share.

[@Kumquatodor]

Merry Machiavelli Mammals tend to be much smarter than birds with far more efficient nerves and oxygen regulation. Not always, but generally.

[@merrymachiavelli2041]

Kumquatodor I'm not sure the oxygen thing is true. In mammalian lungs, Oxygen and CO2 mix internally as we're breathing, This decreases Oxygen concentration and thus makes breathing less efficient. . In avian lungs, however, it's a one-track system. This means that the Oxygen we need and the CO2 we expel don't mix. At least, I believe that is how it works. I'm certainly not an authority on comparative anatomy. I've never heard the nerve thing though, what do you mean? Do mammals have quicker reaction times for something?

[@Kumquatodor]

Merry Machiavelli About Oxygen: We are much bigger (and therefore require more). And, though, they mix, the chemicals don't poison us. It's complex in that manner. We have much faster reflexes. Our twitch muscles allow for much quicker burst of movement. Dogs and cats can pounce so very quickly. Birds have fewer of these muscles. They aren't slow, but they are nowhere near as fast overall as an ape in quick movements. Apes can also answer questions faster than humans; they could press a button when prompted 5x quicker than you and I. This is faster than birds by far. This is a mixture of muscles and nerves that make mammals so darn quick.

[@merrymachiavelli2041]

Kumquatodor Okay, I'll accept you point about nerves :) But that's not what I meant in regards to Oxygen. CO2 doesn't *poison* us, it's just that it means the concentration of Oxygen is lower in the lungs. If the concentration of oxygen is lower, then it means the concentration gradient is less steep. This means oxygen diffuses into the bloodstream slower. Birds evolved to cope with flying at high altitudes, where the air is thinner. It makes sense that they would have a more efficient method of extracting oxygen. There are other things as well. The honeycomb structure of bird bones is far lighter than mammalian bones, yet almost as strong. This is part of what makes birds light enough to fly. Bird feathers are widely regarded as one the most complex structures in nature, with the way the quills interlock at a semi-microscopic level. They have all kinds of properties that put fur, scales, and skin to shame. I would say birds and mammals are roughly equally matched. It's just difficult to way which is more 'complex' when most avian adaptations focus around a very specific end-goal; enabling flight.

[@beeumble6450]

you guys saved me from my final in bio....thanks

[@jessicabane2899]

This was really awesome thanks! :)

[@ktvyas5277]

Great video explained very nicely . Must watch it.

[@melanyebaggins]

wow, the first time I get to watch this and it's not over a gazillian views :D Is it bad that I look forward to these videos every single week? ^_^

[@qdadahu]

This actually just helped me understand why I can only find the gene I am studying (resistin) in lamprey, coelacanth, reptiles and mammals but not bonyfish or birds =D

[@MaryPellyCat]

i used this video to study for my bio test tomorrow. amazing :))

[@heliosphaeresonnen_wind_ki5720]

i would love to know, how the uterus evolved. i mean, from hard-shelled egg outside the body to semi-parasitic growing inside the mum...evolving yolk to a placenta...this seems like such a crazy step.

[@rbcmpbll]

You guys are awesome! Thanks for the vids, I really look forward to them!

[@MeanderingMeagan4]

The aquarium haha - since you catch it with a fishing rod! (when it's snowing or raining, after 4pm, all year round). I can't tell if you're being sarcastic, but I did pick up on it if you were just joking, if not, there ya go haha.

[@DrReginaldFinleySr]

Beautiful, thanks Hank!

[@Auros2525]

It surprised me how, when I received an alert for this video, I dropped everything and yelled "Now it is time for SCIENCE!"

[@fenellaevangela]

As soon as Hank mentioned a fisherman off South Africa I KNEW we were in for a coelacanth story :-D The number of cryptozoology texts that mention the coelacanth are many.

[@mrsdiggory3211]

"whatever hagfishes, still want to join our club but have no vertebrae" fineee

[@ShawnBird]

Why is everyone dismissing this comment? culturekate makes a good point. The most complex chordates are probably the most complex lifeforms but it would be hard to argue that a lamprey is more complex than a mimic octopus.

[@flacawinn]

Thank you, i definitely needed this as a review for my midterm.

[@lauragullan91]

Ahh this video would have helped so much when i was studying for my exams!

[@kalifusch]

You did mention that mammals laid eggs at one point. Apart from the platypus, are there any other mammals that do that or that used to do that?

[@JasonJBrunet]

Teleosts are within Octeichtyes, so either way we're in that group. But teleosts came on the scene relatively recently, after our lineage split off from other fish, so we are not teleosts.

[@theamazingdiscworld]

That was very interesting. Thank you, Crash Course Biology team.

[@WCOBDisorder]

Because, unlike history, science is always open-ended. We can always learn more.

[@couplingrhino]

Among other things, it allows blood to be pumped separately through the lungs/gills/breathing apparatus before it is circulated through the rest of the body, which gives the entire body more oxygenated blood to play with. More oxygen in the blood provides more available energy that can be obtained from food.