How Many Cells Are in a Microscopic Animal?

[@GaryDunion]

This seems like a good place to ask a question I've had for a while: what's the animal with the smallest number of cells but more than one? The animals in this video all have about a thousand, but are there things with just a couple hundred cells? Or a few dozen? Or, like, eight?

[@apothecurio]

The animal you are looking for is myxozoa. A proper animal with around 7 cells

[@GaryDunion]

@@apothecurio Amazing, thank you!!!

[@gudadada]

Check out fairy flies for super small but relatively complex animals. Their cells are super compacted too I believe.

[@GaryDunion]

@@gudadada Fairy flies are incredible. The first time I read about them, back at university, I was certain that the book's statement that they are 0.3mm long had to be a typo!

[@cerberaodollam]

Also volvox and friends

[@petrescuework-difficultcas6581]

6:45 random smiley face floating around 😂 I've never seen a tardigrade with eggs. That's so adorable. I wonder if he puts the animals back into nature after he has done his observations.

[@IVChan]

He keeps them in makeshift aquariums since releasing can introduce unknown pathogens unnecessarily

[@racookster]

If you mean the tardigrade at 7:01, those aren't eggs. Those are the storage cells the narrator mentioned. Tardigrades don't have circulatory or respiratory systems, but they do have those to transport nutrients. They just float around in the tardigrade's body.

[@petrescuework-difficultcas6581]

@@IVChan That makes sense. I just couldn't imagine letting them die on the dish or dry out.

[@petrescuework-difficultcas6581]

@@racookster I was talking about the one at 5:24 which had the caption 'tardigrade with eggs'.

[@itzmedb8290]

looks like a 😐to me

[@revenevan11]

4:52 "Every animal begins its life as a single cell, that is full of destiny" Has to be in the top 2.3% of quotes from this channel, at least.

[@dmitryn9090]

I wish there was some sort of a SuperLike button on KZbin, exactly for such a kind of videos! This video is just next level!

[@Party_Almsivi]

That would be the subscribe button.

[@nicholasalbeck7114]

Playlist

[@tbird-z1r]

Really? Hank getting annoying. Too full of himself.

[@insAneTunA]

When youtube started you could rate the video. They stopped with that.

[@1-800-YLFEN-NAIE]

@@Party_Almsivi I'd say it'd be the share button. Spread the love

[@zanzlanz]

Glorious writing, footage, narration, music, editing, and very tiny actors!

[@FaeFemboi]

I'm reminded of the coastline paradox.. Where measurements of the exact same coastline will will yield drastically different results depending on the unit of measurement used.

[@cumiebaka]

it has nothing to do with this

[@StarSong936]

@ 2:55 I've seen rotifers before under my own microscope. This, however, is something I did not know until today. The first time I saw one was in a high school biology class. That was back in 1979. Yes, I'm giving my age away here. I'm 60 now, so don't tell me I can't learn anything new.

[@emilianomartinez4083]

Found your channel after being curious about the micro biology of the stitches in my hand. Your channel has been helping keep me entertained (and distracted from pain) during my healing process so much as well as ive learned so much about the world we can't see but live with everyday. Thank you!

[@WAMTAT]

Get well soon

[@crow-jane]

Thanks for the history. Makes me wonder how many scientists working in the years around WW2 managed to keep their hands clean.

[@LadyCatFelineTheSeventh]

Why the importance on "clean"? Science today has done much worse. Wait 30 years and watch the cancel game start up again with what is going on today. Actually, it's already started. Seen the big "F" anywhere lately?

[@crow-jane]

@@LadyCatFelineTheSeventh Why? Because it’s my choice to phrase my ponderations on the moral damage inflicted by the military/industrial complex on those caught up in it however I like. It’s a type of context with interesting individual and societal repercussions; the reputation scientists collectively held after WW2 necessitated an entire propaganda campaign in the States just to get more people to take on work in scientific fields and even after all of that there is still this culture of profound suspicion here. I find this both intriguing and relevant. If you want to chat about current events specifically, I’m probably not the conversational partner for you. Have a good day.

[@shifter1089]

Probably none. Give or take your principles.

[@user-hnjga8is1zr6u]

Me too. Working under immense pressure every single second, having to be extremely precise, empirical, and as calm as possible as death is just moments away, staying silent and mindful as explosions and impacts deafen your ears everywhere. My special thanks to them who have worked so hard to make the world a much better place to live in.

[@snakewithapen5489]

You'd have to be an intern in your field lol. If you had any sort of reputation it would probably be only a matter of time until some government came knocking on your door

[@IVChan]

Hanks calm voice is truly amazing but don't let this man distract you from the fact that in 1998, The Undertaker threw Mankind off Hell In A Cell, and plummeted 16 ft through an announcer's table.

[@KissyKat]

WWE? 🤼‍♂️

[@solsoman102]

shittymorph??

[@KaiCalimatinus]

This is the kinds of information Hank comes across as he does his job. To eliminate distraction.

[@dfouigh]

No soy científico ni biólogo, pero este canal me ayuda a entender la vida que nos rodea un poco más. Me gusta mucho la calidad del microscopio, ojalá tuviéramos la capacidad de verlos a simple vista.

[@catpoke9557]

My guess as to why some microscopic animals don't grow new cells is because when you only have about a thousand of them anyways, sometimes losing even just one cell can mess things up for you pretty badly. It's kind of like losing an organ. So they simply don't shed their cells. And if they don't shed them, then aside from healing, they don't need to be able to grow new ones either. It would also explain why sometimes the animals are able to grow SPECIFIC cells in their bodies, or are able to regrow them specifically when healing from injuries. Because what's better than just not shedding your very important cells? Regrowing cells when they just happen to be forcibly removed from you, and ONLY when they are forcibly removed from you. I'm not sure if my guess makes any sense or not, but I based it off of a game I played called Thrive. Something you learn very quickly in the multicellular stage is that if you've only got a few cells, even losing one can be a huge disadvantage and really screw you over.

[@TedToal_TedToal]

I wanted to see you zoom in on an organism that didn’t appear to be made of cells, and show us the cells in each part of its body. I wonder how complex one cell can be? What kinds of pieces does one find within cells of different kinds? Are there 1000’s of different kinds of organelles or structures that can be found in different cells? Do we know what all the structures do? Are those structures always in the same location within the cell, and how does the DNA encode that position? Besides mitochondria and chloroplasts, were any other organelles once independently living cells of another kind? Could the nucleus be that way? How about lysosomes? Just how complex can one cell be? Are there single cells that are more complex than some multicellular organisms. What uetelic organism has the smallest number of cells? I wonder if some parts of humans are eutelic? The retina? Organisms consist partly of cells and partly of secreted extracellular substances. How much of humans is cells and how much is extracellular? How about in other organisms? So many questions. It all boggles my mind.

[@eclipse369.]

Will they ever be answered.

[@HappyBeezerStudios]

Lots of organells, and some of them most likely used to be independent cells on their own, specifically mitochondria and chloroplasts. They later most likely came from blue algae.

[@FloriOnRails]

It's important to always remind ourselves that nothing is disconnected. This is true for life in general but also individuals like scientists. And providing more context like you did in this video 3:45 , I believe helps remind us of exactly that.

[@whatabouttheearth]

I fast forwarded to see what you were refferencing...😳 Jesus Christ I didn't know he was going to go there

[@HenriFaust]

Erich Martini stopped pumps from draining a swamp to slow the Allies' advance through Italy. You should exercise more skepticism in the face of virtue signaling.

[@jeannetteparry5587]

Ftascinating! The variation of species in the same phylum, some with normal cell division and others having partial or full eutely suggests that it is a degenerative condition, the loss of genetic information for cell division. The fact there could also be some adaptive advantage such as conserving resources does not negate this hypothesis. (look up "Genetic entropy")

[@DruNature]

Yes I think about this topic every time I watch one of these videos! I wanna zoom in and see the cells!!

[@ulalaFrugilega]

To think that there is an uninterrupted string of Life from one of these to me, and you is truly awesome.

[@TroyRubert]

It’s important we don’t forget these things even if they make us uncomfortable.

[@TroyRubert]

@Bingo agreed

[@snakewithapen5489]

@Bingo nah I don't think you have to be a loser to get uncomfortable talking about nazi Germany lol. History is notoriously uncomfortable, and it's especially important we retain a conscience and don't become apathetic to the atrocities! Theyre just losers if they don't want to talk about history at all

[@resignurdrnk7535]

the tardigrade bit at the end was awesome

[@limemason]

These deserve way more views. How can people not find this alien world amazing?

[@margitvarganemunkacsi9700]

Wait.... Hank is that You? How did I watch this channels every video from beginning to end enjoying a soothing voice talking without realizing that. Hank Green💚🤓☝Hank Green

[@Pongant]

Thank you for making Gastrotricha more popular. I worked with them for many years (BA and MA) and find these animals fascinating. Your micrographs are always spectacular.

[@UsernameXOXO]

Do they remind you of tiny chest bursters?

[@Pongant]

@@UsernameXOXO Some of them sure do! I don't know if this was already mentioned in of their episodes, but gastrotrich eggs actually seem to leave their mother's body as a chestburster does: the epidermis is ruptured in the process (the eggs are oftentimes 1/4th the size of their mother, mind you)! However, most Gastrotrichs are capable of delivering a string of distinct egg types. So, somehow they survive giving birth.

[@MaryAnnNytowl]

Thank *you,* for taking us along on this journey with you!

[@08binkers]

Oh and after being a big fan of spongebob for so many years.., it’s cool to actually see some of the sea creatures in real life like on the cartoon. Awesome work

[@nathanrey]

This voice is perfect for the "educational" evenings with friends

[@Raverzdreams]

Hank is everywhere, I'm not complaining

[@Magma_Bolt]

How do all rotifers of the same species have the same number of cells? I understand that they are born with that amount of cells, they cannot divide and instead grow, but, surely at some point they'd be harmed by another microorganism or encounter another threat and simply lose some at some point in their lives? In order to verify that the species have the same number and know exactly what that number is then none of the rotifers who had their cells counted could have lost any cells by any means, how is that possible? It can't produce new cells to heal itself so it's not possible to eventually end up back at the number of cells it is born with after injury either. Am I missing something? How is verifying that the number is correct possible?

[@PeterVJaspersFayer]

They only live for about a week. I guess they have to make do with the numer of cells they start with, for that time, until death.

[@Magma_Bolt]

@@PeterVJaspersFayer I never knew they only lived for a week, thanks for the new info :) I still don't understand how the person counting knew that the species number of cells was a specific value when they can lose some and continue living, unless, losing even a single cell means instant death for them? (which I find unlikely)

[@hamjudo]

In the video he mentioned that most eutelic species don't heal. The fixed cell count is for a healthy adult animal. A tardigrade that is missing a foot will be short a few cells. Not only are there a fixed number of cells, there is a well defined body plan. A healthy tardigrade nervous system is composed of a constant number of nerves and the map of neural connections is the same from specimen to specimen.

[@Magma_Bolt]

@@hamjudo Thanks! :3 But I'm still not 100% sure how the person counting knew if they were healthy specimens without any missing cells or not. Did they just count a lot of the same species and the highest number of cells of the entire sample was shared by multiple members so they decided that must mean the healthy ones without missing cells had exactly that many?

[@hamjudo]

@@Magma_Bolt They didn't just count them, they mapped them. They identified what each one did, and how it was connected to the other cells. It was like counting the bones in a normal human. They drew pictures, labeled each bone, gave each bone a name, made a list, then counted the entries on the list. For example, each eye spot is exactly one cell. The mouth design varies from species to species, so it can often be used to determine the species. The researchers carefully figured out what each cell in the mouth did. Some tardigrades have tooth like hard parts, and jaws, others have tubes. They have muscle cells that move the food from the mouth to the stomaches.

[@TheFreshSpam]

Top top video, getting to see things and know things that I would never possibly ever find out about otherwise

[@johngoodwin9606]

Fantastic - reminds me why I support the channel through Patreon.

[@yam-ingtonjr7606]

absolutely beautiful video and wonderful commentary

[@edwardlulofs444]

Fascinating. I heard from a biology prof that humans don't grow new muscle cells. When muscles get bigger, muscle protein is added to the cell. But most importantly, diversity is a law. As a physicist, I have seen the literature that diversity is related to the 2nd Law of Thermodynamics. A system tends toward occupying all possible configurations, because it is the most probable state. So I see it happening in this video. That's what I mean when I use the phrase: diversity = entropy.

[@whatabouttheearth]

The thermodynamic laws are about closed systems but organic bodies are not closed systems

[@edwardlulofs444]

@@whatabouttheearth True. But thermodynamics, like everything is about approximations. In this case the best closed system here might be the biosphere. Study it for yourself. I just had a thought one day and then found that it is an active field of (bio)physics research. I'm not an expert. For example, to calculate the efficiency of an auto engine, it is considered a closed system. Thermodynamics is a very complicated subject.

[@RainVine]

I love your commentary please keep doing this Q_Q ..... most calming, unique, professional narrator out there. The David Attenborough of the microcosmos !

[@Restilia_ch]

Maybe that Gastrotrich partial eutely is to have a number of cells in the body total. If some get damaged, replace them but stop at that desired number. Somehow.

[@scottmiller3975]

This is my favorite youtube channel

[@08binkers]

Your channel and your work absolutely fascinates me. I am a total dumb a$$ and it’s ok but your videos are so easy to follow and I can actually understand everything you are “teaching” me. It’s awesome. Also..., it’s really cool you give credit where credit is due when you need to. Obviously I mean James . I enjoy his channel as well. Thanks man. Seriously. So entertaining. Blows my mind

[@shawnfoogle920]

would be interesting to see the microbes in our body on this Channel

[@jonatanx5163]

Me impresiona lo complejos y metódicos que son sus movimientos, a pesar de que no tienen cerebro, es increíble. Es fascinante.

[@markgisis3242]

I miss those beautiful calming music tracks from previous series 😓😭🥺

[@johnsteiner3417]

It would be interesting if there were a connection between Eutely and the ability to repair the cellular and nuclear membrane of a ruptured cell.

[@fabiozaccarini6762]

oh after 2 years of watching JTMC i just now noticed that you were the Hank from SciShow :D. greetings from Austria

[@EmilyJelassi]

As always, another very interesting video! I might not always fully understand the science or maths, but I Always learn something new from your videos 😊👏🏻💯

[@leelee84701]

i appreciate the soft voice

[@roku3216]

Thank you for this trip to eutely.

[@brendakrieger7000]

Great video🔬🦠💚

[@athenaatwar475]

this is the best video I’ve ever watched

[@guojunpan7915]

Great contents!

[@jayyydizzzle]

6:46 on the right side of the screen there's a smiling cell. Maybe closer to: 😐

[@NowisFurther]

en ingles esta bien, gran parte del placer del video es el narrador

[@tiffanymarie9750]

Not making new cells would mean less chance for cancer? 🤷 In a small enough organism, I could see that being enough of an advantage

[@nariu7times328]

excellent writing! :)

Other comment about the spanish (definitly) automated audio. I know a beautiful female voice actor that could narrate the video for free, and even adapt and translate he script, ask by dm for the contact info (privace security). Great work, as always ❤

[@natoubourgeois]

Very impressive...!! However, I wonder about the liquid in which these microorganisms swim, what does it look like on a microscopic scale...?? Could someone answer me please??

[@jaybingham3711]

Humans only exist as superorganisms. That said, humans are made up of approximately 85 trillion cells. One can breakdown the cells into domains and kingdoms. It's the animal kingdom portion that contains 37 trillion cells. But those aren't more important than any of the others...a point this channel, in particular, should be fully supportive of. So, 85 trillion is the number.

[@andrewevenson2657]

Is this channel a pioneer for this kind of footage of the micro cosmos, or are these pretty standard techniques in the scientific community? And if it is standard, why is this the only place I’ve seen such footage? Are there more advanced techniques, or experimental techniques that aren’t quite ready for youtube because of a lack of quality or something?

[@Vistico93]

And then some of the protozoa we've seen I think are as large (if not larger) than some of these animals comprised of about a thousand cells

[@flavocachata]

You could zoom in and show the individual cells of a rotifer, or how do scientists count them. Or maybe show the tinted nucleus for counting or whatever method is used to count them. Maybe the separation between cells. How big and how small they are. How many cells constitute the rotifers mouth and so on. It gets me a little frustrated because you say to us that these tiny beings are multicellular (I'm not doubting) but not truly showing us that. It feels similar to how they tell us that Siphonophores are colonies of organisms but never dividing them in individuals and showing how each of them specializes in a function,, and showing how bizarre the adult animal is in isolation (separating the would kill them but maybe drawing separating lines?).

[@SquirrelASMR]

That would be helpful to see and I'd be really interested

[@itayl2]

just letting the channel know the description of the video is currently wrong, it mentions Deboki as the host here while it is of course Hank

[@maracachucho8701]

It's true that good deeds won't erase bad deeds, but you gotta remember it's also true that bad deeds won't erase good deeds either.

[@bigbrady2244]

You've got some great footage!

[@onefortheages5983]

Took me longer than it should have to realize this is Hank Green narrating.

[@whatabouttheearth]

Hank Green and several others who narrates this show are co owners of a science media company that does this, Sci Show, Crash Course and PBS Eons (not sure how that works since he isn't on that). The gal who also does narration on this show is a writer and producer

[@ranganathsh989]

Amazing video, excellent explanation.i never seen such video. 🙏🙏

[@slandgkearth]

I know is off topic but the Spanish track of this video sounds like a robot is reading it lacks acting, glad I could turn it back to English.

[@CosmicShieldMaiden]

Love these videos 🖖❤️

[@jaydonbooth4042]

Of course if you wanted the exact precise number of cells in an organism you'd have to count each one individually, which is pretty unfeasible for large animals like people. But we can definitely get close enough estimates obviously, just volume of organism divided by average size of all the different types of cells in it's body, and there you go. There's no really important difference between an estimated range like "about 1.2-1.3 billion cells" and "exactly 1 billion, 273 million, 366 thousand, 254 cells". And like mentioned in this video cell count constantly changes for organisms like us, so it's not even really useful to know the exact total number of cells at a specific time since it goes up and down within a wider range.

[@brendosapien]

Love the video, deeply fascinated by this phenomenon, I still don't think I understand the evolutionary origin of this trait in any greater capacity than the natural novelty of the thing which has been described here. Do we have any idea WHY these species develop this?

[@Shaden0040]

What happens to a rotifer if we destroy one cell?

[@YbisZX]

I think, it has enough cells of each kind to suvive minor damage.

[@PeterVJaspersFayer]

That may depend upon which cell. Some probably have more redundancy than others.

[@herauthon]

it will call support and request an RMA

[@hamjudo]

I have seen pictures of injured tardigrades. Specifically, ones that have lost parts of limbs. Those cute little feet don't grow back. If something takes a bite out of a tardigrade, they will be deformed for the rest of their lives. A tardigrade with only 7 feet was observed successfully laying eggs, so apparently a tardigrade amputee can lead a mostly normal life.

[@Kj16V]

4:37 What's that spinning "worm gear" thing at the top of that organism?

[@jenniferbailey2214]

Cool about the “not glossing over.

[@cloakedsniper5016]

Why did I just learn that Hank Green is narrating this?

[@sciencenerd7639]

great topic

[@clemarusjr]

So if a rotifer is cut in half will they forever be half or does it regenerate?

[@jimmij3894]

So how is the number of cells in a rotifer counted and could apoptosis cause a problem?

[@esteemedclam7070]

Didn't know that Hank Green narrated these

[@johnny14980]

🐐 channel

[@BabyBoomer-vz3es]

What kind of microspce do you use?

[@whatabouttheearth]

They upgraded it since their earlier videos, they have videos mentioning both microscopes

[@RodrigorReyes123]

What kind of microscope are they using in this video?

[@tallonteel6670]

Wish you guys got more recognition fr. Everyone's worried about shitty rap music and trends. This content is amazing

[@jimday666]

@6:45 random smiley

[@lorezampadeferro8641]

It's a problem of mine hardware/software that the audio quality sucks? Stream is not good

[@gilperez3581]

Am I the only one who, after hearing the name "Martini", instantly thought of "Hydatina senta" as a name for a mixed drink? And then started looking for other names to see if they sound like they could also be a name for a mixed drink?

[@RodrigorReyes123]

Does anyone know what kind of microscope they are using in thinvideo?

[@stax6092]

Awesome.

[@ohnoitisnt]

Im new here. Cool channel. Is the existensial crisis about everything living just being a bundle of reacting chemicals and people not having free will a normal thing one goes through? Because this video broke me.

[@BubbaLoob43]

this channels makes me itch to make a microscope for me

[@SuLokify]

Is a cell of a plant not involved in photosynthesis an autotroph or a heterotroph? How about an animal like corals or tube worms?

[@3rd.Eye.Saw.Destruction]

Erich martini was based

[@NoahSpurrier]

Eutely is a nice word.

[@brainstormingsharing1309]

👍👏👍👏👍

Hi, long fan of the channel, amazing work as allways, BUT: The voice in spanish is not ok. Deboki, is that you? If is it, im sorry for what I'm about to say, but your voice in english is really beautifull! If not, I don't know if this is a automated program, you paid for this, or some fan did you a favor, but im really sorry but... nope! I'm from spain, and maybe the international breach with my latin friends can affect, but i think the spanish voice of this video is strident, blank and not interesting. I thought some buzzfeed copy reupploaded the video :(

[@mewt5358]

It's possible that eutely evolved in part due to cancer, at least I think so. Can't get cancer if your cells stop being able to divide. Plus cancer would be really bad for something with so few cells

[@foxhazhax4845]

My answer was simply "yes.".

[@mrmarvellous5378]

Next questions is how many atoms make up one cell?

[@shxdo3712]

I love biology

[@ombra306]

I stayed for the Loud music!

[@NewMessage]

Heck, there are macroscopic one celled animals, so...

[@forgedstone]

Pretty sure this is nightmare cgi. I love it, keep journeying through the unseen world!

[@theglobalwarming6081]

How small are their cells? And can you outline them? Or are the cells too small for a light microscope? I'd assume they are bigger than bacterial cells since they are eukaryotes.

[@bundyb5343]

Doesn't the fact that biogenesis is only known to have happened once here on earth "kind of, sort of" provide evidence that life is extremely rare? In this pristine biosphere that is so perfect for life, should we not have multiple unrelated species on earth if life was common elsewhere?

[@almachizit3207]

It's not exactly clear if biogenesis did only occur once on Earth. This is because prokaryotes mix sporadically mix genes between distantly related species via horizontal gene transfer, which does not always occur intentionally. This makes it really unclear if there was a single common ancestors to all life on Earth, or if there were several progenitor species that have since been mixed together

[@TimeTheory2099]

If you follow Dr. Sagan's thinking, life is abundant. It's intelligent life that is rare. Also we as a species have only seriously started looking for a few decades.

[@bundyb5343]

@@almachizit3207 thank you

[@rbb9753]

That’s one reason (if many) that we are investing so much time/energy/resources in looking for signs of life on Mars, Europa, Titan, and Enceladus. If life arose only once in five potentially habitable world in one solar system then life must be really common, statistically speaking. FWIW, life May well have arisen on Venus as well, but good luck finding any evidence, given its atmosphere and geology

[@GarryDumblowski]

Wait, so, wouldn't _we_ be partially eutelic? Since there are cells in our body that, once born, will never divide again?

[@AlmostEthical]

Once we are born we don't grow new brain cells afterwards. Rather, we lose some in infancy and then that's our final number, discounting brain damage.

[@CrankyPantss]

No. You can’t be partially eutelic. The point of eutely is that it is about the organism as a whole. It’s either a yes or a no. If you have any part of you that adds cells, then you’re not eutelic. Even if you can't grow a new left foot, you can still grow more hair, more skin cells, more liver cells, etc.

[@AlmostEthical]

Putting aside classifications and considering the dynamics, we are born with all of our neurons, and many of those are pruned during infancy. The remaining neurons become larger and heavier over time. So, in those respects, the brain acts rather like eutelic organisms.

[@GarryDumblowski]

@@CrankyPantss Ahhh, fair. Now that I think about it, that's probably what I would have decided too, but I can't say for certain of course.

[@varshakaushik8973]

how do these organisms reproduce??