Stages of Animal Development: Cleavage, Gastrulation, Organogenesis

Before diving into animal diversity, we need a bit more information about animal development, as it will help us understand what we're looking at later. We know that animals reproduce sexually, so a sperm fertilizes an egg to yield a zygote. Then what happens? What is a blastula? What is gastrulation? What about organogenesis? How does one cell become an animal? Let's find out!
Script by Ryan Helcoski
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[@prawn1535]

Dave, you need way, way, WAY more appreciation from the internet. Thousands of students like me flock to your channel for assistance/clarification in every walk of education and science everyday, and I am appalled that the majority don't make sure you feel appreciated. Keep being awesome!

[@mnddcmpnn]

Dave, I appreciate what you do as a science communicator and educator. Finally getting my bachelor's in environmental science and your perspective sets a point of view which is quite helpful. Thank you!

[@timauth]

@@guff9567 Why would you ask that? Because he gave a great compliment as feedback?

[@timauth]

@@guff9567 Ok thanks. Strange, but thanks.

[@mnddcmpnn]

@@guff9567 No, not paid. I'm just a fan.

[@mnddcmpnn]

@@timauth Appreciate it :)

[@martinahernandez9053]

Congratulations on your bachelor’s degree!

[@NateHerrada]

Hey Professor Dave. Last year was one of the worst years ever in my entire educational life. I was pulled deeper into the chains of depression due to academic failure as the year went on. This continued until I had to drop 2 of my AP classes (Currently a HS Junior). I would just like to thank you for helping me bring my way back up to be on-par if not exceedingly past the expectations of my age.

[@mitsunori222000]

Just in time for my students' Introduction to Biology course. Can't wait for the next ones in the series. Thank you, Professor Dave.

[@BoltzSquad]

Hi, Dave please try to make a 1hr session of calculus 1) Differentiation 2) Integration Please make a vedio of one hour in each topic. This will help lot of students

[@blazingstar9638]

I remember going to Kahn academy in 2011 when I was trying to catch up on chemistry at university It’s very helpful! 2h is a tall order , but I appreciate all the info prof Dave gives us for free!

[@ProfessorDaveExplains]

I have a 35 part calculus series, please visit that.

[@beatriztesoro877]

discovered this channel when i was a junior in high school and i still go here for extra learning now as a sophomore in college

[@TheSandkastenverbot]

Great lecture! Looking forward to the next videos in this series

[@meryadamecarretero2726]

youre amazing. im at my second year of biology degree and this help me so much. i love u

[@marianaargentieri1015]

Hi Dave! I’m from Brasil and your video really helped me understand this topic!! Thank you so much :)

[@sciencenerd7639]

this is a very helpful topic

[@michaeldoherty5415]

I came for the annihilation of the globe busters but I stayed for excellent science content like this. Love the channel Dave!

[@oudomchan8299]

Love this, thank you, Pr. Dave!

[@valmid5069]

*Interesting science stuff, Dave!*

[@sciencenerd7639]

hooray, a new zoology video!

[@apollodos]

thank u for the high level science mr. science man. love this channel

[@Stevenn5]

thank you professor Dave ❤️🌷😊

[@blazingstar9638]

This dope professor Dave My kids love it too

[@MaryAnnNytowl]

This looks to be as educational as AronRa's phylogeney series, but with a little different perspective. Very interesting!

[@charleyedwards2121]

this was really coooool prof! you rule thanks for making us all smarter for free

[@beanureeves1787]

Thankyou Dave as always

[@antyspi4466]

Objection your honor! Not ALL animals require a sperm cell fertilizing an egg cell. After all, parthenogenesis is a mechanism of procreation observed in multiple species of invertebrates and vertebrates. On top of that polyps can generate new polyps via budding.

[@shadowmax889]

Just because some species of animals can reproduce by parthenogenesis or budding does not mean that animal as a group cannot be defined as a group of organisms that do sexual reproduction. After all, tetrapods are defined as a group of four limb terrestrial animals even if that is not true for cetaceans, manatees, snakes and ichthyosaurs. Also, there are animals that do photosynthesis by acquiring chloroplast from algae, even if the kingdom Animalia is defined as been heterotrophic.

[@thetigre1672]

Your videos safe me

[@PunmasterSTP]

Gastrulation? More like "Gee, I feel elation" whenever I watch one of your videos. Thanks again so much for making and sharing all of them!

[@four_leaf9110]

Hey dave, it'll be really fun seeing u react to a video called "the history of the entire world, i guess"

[@prschuster]

I liked it when your hair was longer. Otherwise, this was an excellent embryology primer.

[@veronicacarvajal4235]

I love you papa Dave, you're the best.

[@jamiegallier2106]

Thank you!❤

[@bpdmf2798]

How can you have nearly 2,000,000 subscribers but only get like 10-20k views per video? It's crazy.

[@ProfessorDaveExplains]

It's just how educational channels work. I release tutorials in dozens of topics. Students just watch them when they need to for class, not because I released it. They accumulate views over time. Check my chemistry and physics tutorials. They've amassed large view counts. Check channels like Khan Academy or Organic Chemistry Tutor. Same thing.

[@-JA-]

Thank you.

[@akshatgangwar7759]

OMG I can't Tell how much of a treasure you are. Yes sir! I'm shaking rn

[@ameerbader3055]

Proffesor dave,does the relativity theory say that gravity is not a force and is an illusion?

[@ProfessorDaveExplains]

It does not say it's an "illusion". Visit my general relativity tutorial for an introduction to this topic.

[@gzunfariqbalgazanivlogs7197]

Superb

[@helpyourcattodrive]

Hi. You sh do one about what a society is. Like how and why are we in this situation and we decide to go forward and continue or make changes. What is society.

[@helpyourcattodrive]

Great information.

[@cookieman2028]

I am interested in your cat driving school

[@PunmasterSTP]

@@cookieman2028 I am interested as well.

[@redraprs8828]

can say the difference between gastrula and embryonic disc .and also between stem cellsand germ cells

[@kardinaltv2250]

Pls do a video on embryology 🙏

[@mrnobody9465]

Thank you Jesus of PHYSICS & CHEMISTRY 🙏

[@alessandrarafanan3526]

I love his videos but I wish there were pdf notes for his videos so I’m not pausing and writing 😭.

[@akizeta]

Not to be confused with Oregano-genesis, which is a necessary step in making pizzas.

[@areejfatima4392]

Which book used?

[@harshwardhansathe8071]

Thank you chemistry Jesus 💙

[@peasantphotographer3897]

Hi Dave, I'm being a bit cheeky commenting on this vid because its about your debunking vids. I've only just come across your channel and I am very much enjoying it but (for many good reasons) new comments on old vids may not get seen by you. Two points: Firstly, the KZbin ad algorithm is weird - I get loads of ads for the kind of things you debunk whilst I'm watching! Not sure you can do anything about it but thought you should know. Secondly, your book. By advertising it on the vids you kinda put a target on your back. It just gives the loonys a comeback when you talk about charlatans and snakeoil salesmen. I understand the difference between earning a living as a science communicator and being a rip off merchant but I'm not sure everyone does. I'm not saying you shouldn't - it seems like a valuable publication, but perhaps you could come up with a pre-defence when you mention it. Apologies if these things have already been said. I'm going to get stuck into some of your biology vids now; top work matey.

[@helmetongrass1893]

professor dave, im a grade 12 student who has taken biology, im currently studying human embryo developement, my textbook says that after implantation, the ectoderm and endoderm form first then the mesoderm appears afterwards, my teacher claims that this is incorrect and the endoderm forms first by the morphogenetic movements of the cells of the epiblast to replace the cells of the hypoblast and when i search it up on the internet, almost all sources agree that the ectoderm forms first, then the mesoderm and the endoderm forms last, i am really confused please help (i also asked chatgpt, at first it agreed with the internet, then i brought up the mechanism my teacher explained, and it changed its answer to saying that all three layers form simultaneously 😂😂😂, i guess ais cannot replace human teachers anytime soon)

[@hibird805]

YOUR SO COOL

[@theblackbanana1157]

dave he did it globebusters actually posted a lunar eclipse video. ive just watched it and i dont really see how its proving everything that was supposed to be redeemed and i feel like you could IF YOU WANTED TO and no im not trying to be like oh hey you need to go do this you knoe but only if you want to now go do it, but actually thinking about if you really want to spend another second of your time on a lost cause like flat earth long story short you can make content out of globebusters

[@Night1989]

Dude, where are your religion videos? I think i can remember you even attended a livestream with some guy.

[@cpt.battlecock5264]

Since you brought up anatomical positions,does the butt of a human lie in the ventral or posterior end? Most people refer it as posterior but people stand up straight which would give our butts at the ventral side and not posterior side.

[@helmetongrass1893]

i think you mean dorsal? not ventral? and i think that most people refer to it as posterior because several animals dont stand up straight and we just follow the general trend for humans too

[@limpfall13]

So iv been doing my best to read articles on the comparison and comparability between budhism and science I’m not saying they are or are not I’m not well educated I either budhism or science to answer that’s why I want to gather opinions and ideas So I want to see if there are any underlying conflicts between the relgion and science and if there’s ways to avoid (malicious Versions of) religious marketing like..idk I’m trying hard to think constructively and critquely but I’m young and usualy tried idk if you can answer this or give any insight Dave it’s fine if you don’t I just am trying to stay scientific but also stay within my relgion healthly

[@Jack-jd6tj]

I stg i always thought you were (cr1ticle) or penguin0 the KZbinr and we’re just making a joke or somthing or just talking about random stuff. This has been going on for a couple months cause I never really clicked on any video

[@giorgibregvadze49er]

Remember 2 years ago when you promised (on ask Dave number 5) that you will do a political science playlist ya… you haven’t done it And I am waiting for you to do it.

[@ProfessorDaveExplains]

I have someone writing it right now! He had to take a break, should resume soon.

[@wmgthilgen]

I've alway found it ironic how we humans refer to what's become known and accepted as the lower form of animals but at the same time, can't fathom that humans are animal. And that the only thing that I have come to the conclusion that separated humans from the suppose lower form is the fact that only humans not only have a concern but an obsession with purpose. Without it, humans can't fathom our existence. It's ironic how the one thing that separates our existence from any and all other life forms, purpose is the one thing that will cause it to end.

[@ProfessorDaveExplains]

That's a symptom of our higher cognitive function, which is what I would say separates us from other animals.

[@angrydoggy9170]

A bit of a click bait title as there’s no cleavage in sight. But interesting nonetheless.😋

[@TeslaTales59]

Sir, Have you explored debunking steven greer and his alien non-sense?

[@noirlavender6409]

If the earth isn't flat how come we don't have globe monitors? take that you globehead! also thanks for the new video this is really cool m8

[@helmetongrass1893]

globe monitors?

[@thew-heat5525]

Hay just though of this. Ask the flat earth crowd to explain this. The Arora borealis, this happens do to the solar wind pausing over the magnetosphere crating a natural friction and discharge in the earths atmosphere resulting in that strange glow only found in north and south poles. That strange glow dose shift a bit north and south from time to time but stays mainly in the north and south pole. Having said that this is my point. If the earth was FLAT, this natural friction and discharge in the earths atmosphere with the glow, would be in a different place but its not; this magnetosphere " magnetic field " is also spherical. Tell these primitives to explain this.

[@krishnaabhilash7701]

Prof. Dave, i have a question...are scientists (or cosmologists?) sure about the age of our universe or is it "13.8B or more" type? And can u make a video on why this kid is wrong? I would appriciate it...anyway this is the title of the video: *GOD exists (Stephan theory proved wrong) by a kid!*

[@KingZorLink21]

Just curious but what’s ur IQ

[@vegatronld]

Do cool

[@vegatronld]

"so"....lol

[@beter7886]

Cleavage lol

[@JohnDoe-bg2tc]

"Cleavage" huh? :)