Before there were interwebs I did a whole doctoral thesis on life at low Reynold's number. If I may offer a pedantic quibble. Water isn't more viscous because you're teeny. The viscosity remains the same (as does the density). Teeny things tend to have greater surface:volume ratios than less teeny things so the slidey/sticky forces (viscosity) are relatively greater than the hitty/pushy forces (inertia). A narcolepsy-inducing plethora of detail can be found at Crenshaw, D. G.: How interstitial animals deal with viscous flows. Ph.D. dissertation, Duke University 1980

@Darticus42

6 жыл бұрын

I love how you describe this

@paulthomas8262

5 жыл бұрын

haha

@MikeMayer7

5 жыл бұрын

I came to say the same thing. Viscosity is an intensive property; it does not depend on system size or scale.

@aidanlevy2841

5 жыл бұрын

I think "here is the dissertation I defended on the subject" is quite possibly the best internet credential I have ever encountered :) also good job on your hilariously pedantic but self aware quibble.

@kellyjackson7889

5 жыл бұрын

Crenshaw, bad news.Some of us at the faculty were reviewing various papers including yours and I happen to spill my 'grande' all over the desk. Story short, there wasn't any paper towels available and my daughters kindergarten drawings were in peril. Soo well I think you get the picture. Sorry old chap. DU.

I've worked in a Aquatic Ecotoxicology Laboratory a few years back. One of my jobs there was to take care of the Daphnia. I had to cultivate the algae we used to feed them, feed them, prepare their culture medium (water), change it, separate them, and try and multiply them. We used them as biological indicators to test the toxicity of effluent water from industry. Basically, we would make several dilutions of the effluent water, deposit a number of young Daphnia (1-2 days old) and incubate for 48h. After that we would count the number os surviving Daphnia for each dilution to see if the effluent is safe to dump into rivers or not. They are extremely sensitive to toxins and stress. Every glassware used with them had to be washed with neutral soap, and be rinsed 50-100 times. One time one of the cleaning ladies thought it was unnecessary that much rinsing, and it killed 90% of our Daphnia. (Figuring out what was happening as day after day they were dying was "fun").

@H0A0B123

6 жыл бұрын

Do you think the ones that survived are less sensitive?

@MateusAntonioBittencourt

6 жыл бұрын

Maybe... Or maybe they were just lucky. No way to know without investigating further, thing we didn't do. But we needed to "borrow" some from another lab to be able to regrow our population to have enough to continue to run the tests. So even if only the more resistant survived... it didn't affect the results down the line.

@EddoWagt

6 жыл бұрын

How many did you have before the apocalypse began?

@Barnaclebeard

5 жыл бұрын

Cleaning "ladies"? Really?

@binra3788

5 жыл бұрын

Are you allowed to go the other way and explore vital, rich or health-giving water? Ie after vortexing the water rather than simple degrees of concentration? I expect the job-spec dictates finding what can be gotten away with and certified 'safe'

Since you asked, I can tell you as a biologist that putting a microorganism under a microscope can be stressful for them and can in some cases even kill them. For example, if you are using a microscope with a light bulb to observe them it can get really hot over time and can literary cook them. This is the reason why most of them will hide or move to the sides of the "object glass". This is also the reason why I usually used dark-field microscopy when we had to draw microorganisms we saw under the microscope. It made them more "comfortable" and they stopped moving and running all over the place :P

@plint99

4 жыл бұрын

This is a blatantly false statement I'm sorry to tell you. I've been working with microorganisms in this exact same way for 43 years and can say undoubtedly with an accurate amount of uncertainty that the neutrinos will not be affected in solution. Therefore you're wrong and I wholeheartedly disagree with that statement and any further statement you try using to defend your ignorance. Good day.

@stockbrotsalat7577

4 жыл бұрын

If something is deadly for microorganisms, it still doesn't make it stressful for them.

@protheu5

4 жыл бұрын

@@plint99 Stressed much?

@benfillman4049

4 жыл бұрын

@@plint99 and when the fuck did we start talking about particle physics who said anything about neutrinos

@tardigrade9493

3 жыл бұрын

@@benfillman4049 It's a malopropism, a reference to an amusing line from a sci fi movie to explain the end of the world, "The neutrinos have mutated." See comedian Dara O'Briain's take on it.

If it turns out that people have been getting false positives because they've been adding hot coffee… o.O

@InvadersDie

6 жыл бұрын

Impossible, everyone doing science knows coffee is a cold liquid

@kamoroso94

6 жыл бұрын

They wouldn't add coffee, they'd use caffeine directly.

@PhilBoswell

6 жыл бұрын

Whoosh…

@happydays3746

6 жыл бұрын

A paper cup offers pretty limited insulation so obviously coffee is a cold, or at best lukewarm, liquid by the time your apprentice gets back from the cafateria with it. I do hope though that the daphnia involved in this debauchery know only the 1st one's free & they'll have to pay for their next hit!

@BothHands1

5 жыл бұрын

@@happydays3746 😂😂😂

The real reason the liquid seemed more viscous under the microscope is because inertial forces are hugely dominated by viscous forces at small scales (Reynolds number). In other words, the liquid's momentum cannot overcome friction. In a coffee cup, the liquid's momentum is much higher so it takes a while for friction to slow it down.

@Czeckie

6 жыл бұрын

thank you! I was really sceptical about water having different physical properties on millimetre scales. It's the effect of small forces not small distances.

@enzldavaractl8345

6 жыл бұрын

Also surface tension becomes a much bigger deal at those scales

@praveenb9048

5 жыл бұрын

Thanks for the shout out to good old Reynolds. I think it the discussion would be incomplete without a reference to R.

@snap-off5383

4 жыл бұрын

"The fastest way to learn the right way to do something or how something really works is to post a youtube video about it titled that 'this is the correct ______' showing or telling it wrong, then wait for the comments to roll in. "

I keep Daphnia as pets, watching them have little mini baby daphnia inside their "shell" is so cool! Also those large front "legs" are antenna used for moving about. The jumpy way they move is how they got the common name water flea.

@suzannep

6 жыл бұрын

A side note, I don't put them on microscope slides, I keep them in a shallow dish if observing under the microscope. It does make it more difficult to view them, but they get to swim and eat freely.

@okhstorm

6 жыл бұрын

I want some daphnia as pets! Will Google where to buy them from

@mirensummers7633

6 жыл бұрын

They have a really interesting reproductive cycle, swapping between reproducing asexually in the spring and summer to sexually in the autumn to winter when food availability is low. I'd be interested to know if they remain asexual when bred in captivity because resources remain constant

@MCWaffles2003-1

5 жыл бұрын

you can buy them from a local pond, just throw two cents in

@garymills6702

4 жыл бұрын

You need to get out more! (Don't get upset I'm only joking)

Released them back into their natural habitat: water. _Flush_

@elektrolyte

4 жыл бұрын

LOL zacktly

@Mihoshika

3 жыл бұрын

My thoughts exactly.

@Aquascape_Dreaming

3 жыл бұрын

😂

The fact that you actually took the time to be ethical about something as small and seemingly insignificant as a daphnia shows how caring you are about the things you study. Very nice

In my experience looking at water critters under a microscope, I have occasionally gotten the sense that they become increasingly stressed after long periods of time. The only reason I say this is because I've seen them become either more sluggish or more active (maybe even frantic), if they're on there for more than 5 minutes, and my guess is that the heat from the microscope light might stress them out. Or possibly the light itself, especially if their natural habitat is murky pond water. I appreciate your addressing ethical concerns, but I also think a few minutes under a scope is probably not any more stressful than, say, evading a predator in its natural environment. As long as you monitor it for signs of stress and don't keep it on there too long, and then return it to its natural environment, I don't have a problem with it.

If viscosity changes with size, does a hunchback whale feel like it moves through air?

@bhargavaudayagiri603

4 жыл бұрын

That's an interesting thought, but the ratio of the sizes of a human and a hunchback whale is not that significant compared to the ratio of the sizes of a human and daphnia

@VyvienneEaux

4 жыл бұрын

The viscosity doesn't truly change; it's just that things with more surface area experience greater intermolecular forces with water. Interestingly, hunchbacks do take advantage of water's viscosity to maneuver, which is something humans can't do whilst skydiving. They get a "grip" on water using small tubercles on their flippers, which greatly expand the surface area of each flipper as well as create turbulance (which is useful for the same reasons that professional divers make small splashes and don't get hurt whilst belly floppers make huge splashes and do get hurt).

@MangledShepard

4 жыл бұрын

The hunchback whale of Notre Dame 🐋

@MangledShepard

4 жыл бұрын

Just google hunchback whale see what you get

@erikb3799

3 жыл бұрын

Air has a much lower density, so water wouldn't feel like air at all. As someone else said, the scale between whale and fish isn't as large of a ratio as the fish to daphnea.

When I did this experiment in highschool, we didn't find any correlation between caffeine and heart rate. We also used alcohol and nicotine, and these produced notable results

@somaannn

2 жыл бұрын

How much caffeine

You'll actually find that a fish's swimming motion is also asymmetrical in time. Here's a great video I found showing that it moves in a more wave-like pattern: kzread.info/dash/bejne/fH2by8qsg9zLgpM.html

appreciate you addressing ethical concerns. and also, accepting a sponsorship from something that seems to actually be good and interesting.

@Viplexify

6 жыл бұрын

I'd like to remind you that this guy wants me to pour coffee onto my daphnia, and he doesn't address any ethical concerns at that part.

@Muonium1

6 жыл бұрын

It's a daphnia.... its entire body is a couple millimeters wide, its brain consists of AT MOST a few thousand neurons. There is no possibility for consciousness let alone anything like what could be described as suffering in such a simple organism. A honeybee has a million neurons and it's not even clear THEY have conscious experience. There are no real ethical concerns experimenting on daphnea.

@user255

6 жыл бұрын

Ethical concerns? If we are concerned at that level, we can practically do nothing without causing "suffering". Not even kill ourselves without destroying home of millions of microscopic animals.

@Muonium1

6 жыл бұрын

Ummm I don't know what you are drinking but I'm pretty sure my chlorinated municipal tap water doesn't have any daphnia in it....

@karmakazi219

5 жыл бұрын

@@Muonium1 He only drinks pond water.

Finally an explanation for why my fish died when I put it in treacle.

Your videos have always infinitely fascinated me. I love the way you get distracted and run on a tangent, like an excited 5 year old. It's this obvious passion you have that makes your videos so magical. Thank you so much for wanting to teach us about these small details in life, we really dont stop enough to appreciate the little things that have us here in the first place. Again, thank you. you are wonderful

Steve, you should try to measure the rate of the daphnia's heartbeat and use it to calculate the temperature--a biological thermometer.

@TheJunky228

3 жыл бұрын

ooh that would be a neat idea

@muffininacup4060

3 жыл бұрын

I think it will fluctuate a lot depending on other factors, but it would probably work as an approximate

@VoltisArt

22 күн бұрын

@@muffininacup4060 age and size come to mind. We may not immediately note a 20% volume difference (only about 7% difference in each length, width and height) in something that small, but the resulting heart rate could easily skew results significantly.

One of my favorite animals, obviously. Well done video. Kudos for not killing them.

I never do this, but VERY well played sir on the sponsorship! Fits perfectly with the content, looks interesting, and not over done at all!

I really appreciate the care and consideration you took to returning the daphnia to their original habitat. Most people wouldn't offer them that level of consideration, because they see the world as something to exploit for their own gain.

My first video on this channel. Never subbed so fast in my life.

@rpyrat

6 жыл бұрын

Welcome!

@bartschellings5272

6 жыл бұрын

really? and i'm just here expecting your comment under any yt video I watch :D how you do this?

@sebastianelytron8450

6 жыл бұрын

Bart Schellings You will find that these science channels have ~90% the same subscribers. If you watch one, you watch all of them. Commenters are usually the same people too. My comments are just one of many :p

@kingvendrick8919

6 жыл бұрын

watch his video where he bounces a laser off a mirror that's on a speaker, you won't be disappointed.

@DukeBG

6 жыл бұрын

Or any, where stuff is poured out of beakers.

I love how you’re talking about the relation between chemistry and biology because I used to always say that life as we know it is just an ongoing chain of chemical reactions.

@iwanttwoscoops

Жыл бұрын

you certainly weren't the first to say this...

We did this experiment in 9th grade biology using things like caffeine and adrenaline I can confirm that the heart rate increased dramatically when exposed to a caffeine solution at room temp, but I can't rule out that other effects like osmotic pressure or simply the Daphnia reacting to caffeine as a toxin and trying to escape caused the increase in heart rate. At the end of the lab I used a little to much caffeine and the water flea's heart stopped, so the ethics maybe a little iffy.

@654pedro123

6 жыл бұрын

The ethics were out the window in the first 7 words you wrote =P

@JayfeatherFan1000

6 жыл бұрын

PETA's gonna be pissed.

@theywalkinguptoyouand4060

6 жыл бұрын

Adam Wiess yeah no one believes you cab "confirm" anything you do in 9th GRADE BIOLOGY

@yangxiaolong1392

5 жыл бұрын

Was the coffee heated, or was it room temperature?

@gabrielv.4358

2 жыл бұрын

Oof

Really enjoyed this video. The explanation and content held my attention very well.

Great informative video as usual, thanks Steve!

Not positive, but I think your description of a fish swimming in water may have been a bit off? Or at least not detailed enough. I don't think the motion of a fishes tail is time reversible. I think the point you may have been trying to make was that at the daphnia scale fluid is not behaving in an inertial way, Which I totally agree with and yes it is very cool. I do think that lower apparent viscosity fluid locomotion is not time reversible. Birds wing flaps are certainly not time reversible, and air is a much less viscous fluid. I don't think thers is much in a bird wing that we could pull out and still have birds fly. Even those dragonfly toys which look very reversible critically have very flexible wing membranes that move in a way that is not time reversible. Escaping lobsters or shrimp swim/move in a similar way to daphnia arms and are much larger, proving the method still works with a fluid behaving in an inertial way. It is true that simply flapping a stiff tail works just fine, as proven by simplified fish toys. I still don't think these are time reversible, however, as body movements follow tail movement. I can't picture that working in reverse, the tail would just be moving at the wrong time in relation to the body and the fish would not move. Tuna seem to move in this way, with stiff tails and very stiff motion. I just don't think there are many time reversible solutions to moving through a fluid in nature. Propellers would be an obvious counter example as they are time reversible, but animals were never able to make wheels or rotating parts, and euglena are the only real example of a motor in nature that I can think of. I could be wrong, I'm not a biologist and have not studied this extensively, but wanted to bring it up anyway as fish and birds are incredibly cool and may be worth speaking about in more detail. fish swimming analysis kzread.info/dash/bejne/o4hq0a-mmZzXoLg.html kzread.info/dash/bejne/l6GdpLuGfLG4Z7w.html kzread.info/dash/bejne/nWt-rrBrm6vFerQ.html kzread.info/dash/bejne/dYZ4qNuKc9Kuoco.html Fake fish kzread.info/dash/bejne/aGlhpNB_dNiwaM4.html kzread.info/dash/bejne/amF4yLmloqqffso.html bird wings kzread.info/dash/bejne/Y3iMpM5qmMjfhLQ.html kzread.info/dash/bejne/dpts2slthZq-odY.html Lobster kzread.info/dash/bejne/Zqd8j6qNgZrcnNI.html propeller kzread.info/dash/bejne/p56OltmYfM-7n7g.html

@BenNBuilds

6 жыл бұрын

Phi6er yea a simplified propeller, like two rectangles at a 45 degree angle on a shaft would be time reversible. The vortexes make it not but if you simplify and ignore that it's time reversible. Probably

@vampyricon7026

6 жыл бұрын

Birds flying through air isn't an apt comparison, I think, because they also have to rise up. If you're speaking if propulsion in one direction, like placing a flappy fin on the back of a trolley, it'd propel it forwards.

@BenNBuilds

6 жыл бұрын

Vampyricon a bird maintaining altitude and flying forward is just a more downward pointing thrust vector. rather than straight back it's a bit of down and a bit of back, i.e. At an angle

@vampyricon7026

6 жыл бұрын

BenNBuilds But they're not using the same method of propulsion. A fish has a fin on its tail that propels it forward. A bird has wings on both sides.

@BenNBuilds

6 жыл бұрын

Vampyricon the point I was trying to make is bird wings operate in a very inertial and low viscosity fluid and are not time reversible and would not work if they were. Bird wings move and are very successful operating in the same way as daphnia arms, even though the apparent fluid is completely different. Not sure where Steve was going in the video but its not a huge deal

Great video, thank you. My opinion of the ethical aspect you bring up is I believe or assume they have no concept of should. So if they survive their trip to your apparatus unharmed physically all is well. Its not that the experience "should" not have happened. From their perpective their senses showed some strange things for a while and then didnt. Seems like dehydration, pressure and potential overheating from the slide light would be concerns. I appreciate and agree with your outlook on this. Why destroy beautiful things if you can avoid it?

@ReasonMakes

2 жыл бұрын

I agree with everything except the notion that whether they can conceptualize what 'should' happen is relevant to the ethics. All that is relevant is their capacity to experience life; to have wellbeing and/or to suffer. They have some form of a nervous system so therefore we should err on the side of caution and assume they are sentient. And if they are sentient then we shouldn't exploit them or harm them when it is unnecessary. Observation is fine as long as it doesn't interfere with their wellbeing negatively. As you pointed out, the heat from the light source could likely be uncomfortable. As interesting as the topic is, I don't think this video should have been made. At least not in this way.

@bunberrier

2 жыл бұрын

@@ReasonMakes Well said. I dont mean that "should" effects ethics here, I meant to point out there is a capacity for suffering in being able to imagine things being different than they actually are, and comparing that conception to reality.

I wish we had footage of you pouring the daphnia back into the pond from your beaker.

@Humineral

6 жыл бұрын

"returned to their natural habitat" Yeah, the toilet. lmfao

@68wayupintheskyftw61

6 жыл бұрын

Cause they matter at all?

@trdi

6 жыл бұрын

LOL. I honestly think there's zero ethical concerns with these. The video itself was great, though. The part about biological organism being consequence of the chemistry is quite deep and is in inline with my view that we are also just slightly more complex automatons, just a step above trees.

@Varksterable

5 жыл бұрын

Scott It doesn't look like the other commentors got your point, but I did. Nice one.

@maxxcastillo9347

3 жыл бұрын

I know this is an old comment, but I find humour in the idea of terrifying others when they see you taking samples from a pond, and especially when they see you pouring an unknown substance from a beaker into the water

Fantastic video as always! thanks!

Fascinating... really! Thanks for the explanation.

Steve you seem like a all around good person with good decency and so on,I'll bet people in your life see you as a good friend

Your videos have helped me with some tests and just good videos over all

I have done this experiment multiple times with my daughter at the Denver Museum of Nature and science and we have always seen the result. They provide caffeine, sleeping drugs, and other substances to test out. Using a high speed camera that records for a fixed amount of time each run the effect is small but measurable and repeatable.

Great vid, really fascinating and reminded me of a few things I learnt at uni!

I love the "how do i do that" while making the point that its the same exact motion. His brain broke for a minute before it realized "oh, just wiggle your hand".

In at least two respects, you got a bit hyperbolic here. 1. The viscosity of the fluid is not changing -- only the organism's ability to move fluid due to its shape, mass, and power v.s. the density and resistance of the fluid. 2) The propulsive movement of a fish's tail was oversimplified.

@crackedemerald4930

6 жыл бұрын

Tom Eubank the viscosity is the same, but the atoms are bigger for the water flea than for the fish or whale

@timothystoutland6961

6 жыл бұрын

Pedro Rocha although you are correct in fact. In practice the effect from change in ratio is so small as to be almost immeasurable. A minnow may be one hundred times as big as a water flea. The drop of water on the flea or minnow contains 1,670,000,000,000,000,000,000 water molecules. Put another way, a whale may be many thousands of times as big as bass. Yet when compared to the whole solar system, the difference is small indeed.

@ScienceByMike

6 жыл бұрын

1) There is a point where water no longer acts like water. Now this is super tiny 100-1000 molecules. Now this is much larger than a water a few 1000 molecules. If you put a spec of dust in water it appears to move around. This actually stems from the water molecules bouncing off of it. I am not sure about how water changes from a fish scale to a microscopic scale but I am sure there is a measurable difference. 2) He starts the fish analogy saying "Think about the way a fish moves, very crudely..." right there he admits its over simplified so what is the point of your number 2?

@OriginalOmgCow

6 жыл бұрын

The entire video was pretty awful. He spent half the video (5 minutes) describing how heat speeds up reactions and size to density calculations and never getting to the point the title specified other than "can someone provide me proof". Downvoted for it too.

As long as you gradually climatise the Daphnea to new temperature water, use the water from its habitat, and make sure you don't heat it up too much (which can even be done with the light) then it's completely ethical.

Extremely cool video. That’s nice that you care about the ethics. I wouldn’t have thought about it actually but then I’m one of those people who kill bugs without caring. Absolutely love that you made this video to share how cool that microscope phone add-on is. If I didn’t see how great it works I would have been to skeptical to actually buy one. And I am definitely going to buy one. The product is great, looks fun and interesting. One last thing, can you get Daphnia out of pretty much any pond? And are they simply there ready for the taking? Or do you have to search for them? Meaning are they rare or will every cupful have Daphnia? You do such a job making interesting videos and you explain things so well without it being confusing or boring. Thank you for sharing. So glad you make videos.

It's fascinating that you showed the asymmetric motion in the daphnia legs moving the water around! Tbf, some organisms smaller than daphnia can also move around in (different types of) symmetric motion despite their body size and the water viscosity. Like E. coli bacterium swims with its rotating flagella, following the radial-symmetric motion, which could look the same when time is reversed.

My chemistry Prof. Said it well, Chemistry is the interaction of electrons between atoms and molecules. The effect of temp changes makes more sense if you take into account that the more energy you give an atom the easier it is to remove an electron.

You reminded my college days , and nice explanation, thank YOU

omg i love your channel

I really respect you, for respecting life, no matter the difference in scale. We should follow your example when conducting research on living organisms. Well done ❤

Love your videos

This is a great ad for that microscope. Would not have guessed the footage was from a phone attachment, or that one would look that good

This is a GREAT VIDEO!

Truly underrated channel 🤘🏼

Does that kind of "time reversible" flapping even work in less viscous fluids? I figured the flapping of a fish was more like a sinusoidal wave propagating from their heads towards their tail fins, like the way snakes do it...

@stijnkok

6 жыл бұрын

That is true for most fish, although plenty only use their fins. And I think tuna swim by actually flapping their tail back and forth very rapidly. At least, that's what it looks like...

thanks steve for being the only science youtuber brave enough to tackle fluid dynamics

Does anyone have any footage of a fish flapping in slow motion? I would have assumed it was not time reversible.

@davidvirgilio4166

6 жыл бұрын

In my crude preliminary search I found that most fish move their body in a wave. So there's a directionality of the motion from head to tail. So I'm just wondering if there are better examples to highlight the difference between the reversible and nonreversible motions. Any ideas?

@luffyorama

6 жыл бұрын

I think so too. It's like how snakes moving, but in faster rate?

@sansamman4619

6 жыл бұрын

he talked about the motion for example if a fish was to do that motion reversed it would still be able to swim.(ignoring the other body parts so technically not a fish.. )

@frechjo

6 жыл бұрын

Yeah, I was looking for this comment. Fish swim in a wave, so if you reverse the motion, they should swim backwards. There are some fish that actually do swim in reverse. And they have scales that favor a forward direction.

@Blackmark52

6 жыл бұрын

David Virgilio "fish move their body in a wave" Yes, but that's not the comparison Steve was making. He confined his observation to the tail because he was analyzing symmetrical movement in a viscous liquid.

How did you get them to stay in the same location so well

I work with plant pests and the first time I put a leaf under a microscope and tried to view the aphids or mites or whatever it was, and watched them run away from the light of the microscope, I was really taken aback. That these tiny creatures would even have a sense of self-preservation shocked me. I had never even considered before that a microscopic organism would display fear. Do they also feel hunger, pain, cold? Lust? Does all life suffer?

"No Daphnias were hurt during the making of this video" 😊

2 things i believe are wrong: 1>time reversibility is more possible in viscous liquid as reynolds number is lower. look up G. I. Taylor experiment it will blow your mind. 2>how fast a reaction happens chemists use Gibs equation so $G=H-\Delta S\cdot T$ so in reaction where the entropy decreases at a cost of enthalpy then the reaction will be faster at low temperatures. These reactions are endothermic and will cool down the enviroment aswell. You were talking about exothermic reactions.

8:20 Congrats to the expecting mother

A video about Euglena would be interesting. A organism that is both a plant cell and a animal cell

Hi, Steve! I'm puzzled for a while with a question of miscibility of liquids. Why do some liquids mix and some do not? Answer: "Cuz of density" is not sufficient. What happens on the molecular level? Which forces make two seas or oceans of different saltiness form a wall? I guess, an answer to this question could make a pretty decent video.

You are so goddamn good at what you do. Finest human kind. Congrats.

It isn't the viscosity of the liquid that changes, it's the surface tension

Wonderful video! Great information. But (a qualified but) at 9:08 where you ask whether it is stressful for a daphnia to be put under the microscope - great question for macroscopic creatures such as ourselves, but not only does water change its character with scale, but SO DOES ETHICS which becomes completely different at that scale. Do we consider the bazillions of Daphnia that get cruelly crushed by the sand or sediment in which they are encased? There are SO MANY , SO MUCH MORE HORRIBLE deaths of Daphneas happening ALL THE TIME, EVERYHERE, that it makes no difference whatsoever in the grand scheme of things what happens to them under your microscope slide. That said, I applaud and share your sense of fellowship with the tiniest creatures of the earth, and I would have done the same, let them back into the wild - not for them, but for my own sense of fellowship with those tiny creatures!

Considering most people don't care about the welfare of large sentient animals like cows, I don't see why this would bother them.

@654pedro123

6 жыл бұрын

I would guess Mould isn't adressing those people.

Daphnia are definitely the cutest microorganism I've ever seen

You returned them?! You sir, are a good man. I believe it is obvious that almost all life feels pain, hence how it reacts to pain which increases chances of survival. Even single cell life.

i’m so glad i saw this

Your description of the rate of chemical processes & how they're affected by higher temperatures, gave me an intriguing thought: What about those reactions uniquely occurring at only the higher range of temperatures? Like in explosions for example. Note that I'm referring to chemistry that isn't a part of the actual explosive reaction itself, but could only be done under the unique conditions that exist at the extraordinary heat & pressure caused by an explosion. (I know that explosions have been used to fuse together different metals, but am uncertain whether this is really a chemical effect). Or those seriously extreme temperatures *just before* electrons become stripped away from their atoms & the substance becomes a plasma? What kind of interesting chemistry could *only* be done under these conditions? ~~~ Thankyou for specifically mentioning the *Ethical Responsibilities* that come with biological research. Ethics are an important part of science that are - unfortunately - all too often overlooked in documentary work, especially when the focus is to both inform & entertain. With the amazing potentials coming from many modern technologies (Like CRSPR-Cas9 for example), maybe we should be asking less *how* we can do some things, but more *if* we should do them at all?

6:40 But the fish fin movement isn't really reversable: the fin bends in the opposite direction to flapping, so the water is always pushed backwards If you really reversed the motion, a fish would start "digging" / "grabbing" the water with its fin, just as a daphnia does, and would move backwards all the time

A fish's flap isn't really really time reversable though, since it moves in a slithery motion, angling it's body and tail fin. Same with the flapping motion of a bird, where the bird will angle its wings like a propeller.

great vid man. I got a microscope like that for my phone for Christmas! pretty cool.

I like the fact that the way you've framed this shot, the shadow of the beam on the wall behind you frequently lines up with your beard/mustache. Just a fun composition thing I noticed. Blame art school, lol.

I think it's funny how people get so tied up in that one microscopic organism they displaced when they don't think about all the bugs they kill when they move ANYTHING... lol it's futile.

@cortster12

6 жыл бұрын

Marcus_Mravik Logical, people are not.

@snap-off5383

4 жыл бұрын

"All for one and providence for all said the Elephant as he danced among the chickens".

@tardigrade9493

3 жыл бұрын

But that one daphnia benefited from his gentle care. It's a start.

Increasing temperature only increases the number of collisions very slightly, the rate of reaction increases mainly because of the increased number of successful collisions.

It is like fast-forwarding the daphnia's life by increasing the temperature. It goes through its life more quickly.

Have a look on fairyfly (Myrmarid wasps). For they are so small that the air is viscous and they have fringed wings.

There's a spectacularly approachable book on fluid dynamics called Life in Moving Fluids by Steven Vogel. It's an introductory textbook to fluid dynamics for practicing biologists (which I am not). I read it on Bill Mollison's recommendation and it was one of the most insightful books I've ever read.

Thanks for returning the daphnea to the pond.

I never tried caffeine on Daphnia, but I did turn them pink with increased dissolved carbon dioxide in their water, for a school project. It involved releasing carbon dioxide from an acid/carbonate reaction and bubbling it through the water in gradually increasing levels to see at what point the Daphnia would become pink.

2:05 Is that why it’s easier and faster to mix sugar in hot coffee rather than iced?

Even though the temperature effect on reaction rates is very common, it is not the full picture. There are reactions that can be slowed down by higher temperature. We call this behaviour anti-Arrhenius.

One question: Is the water going around it because of the size and shape of the drop? (Because the surface is surrounding it closely) I mean, if it were in a large body of water, in the middle of a pool, would the water still circle around it? Or would it be pushed more freely to other random directions?

I think the connection between temperature and chemical reactions you presented is a bit off. Temperature as a factor is usually used when it comes to chemical equilibrium which is basically two counter acting chemical reactions. If the "forward" reaction is exothermic and you increase the temperature, the "forward" reaction will slow down and the "reverse" reaction will speed up in order to counteract the increase of temperature. That's described by the van 't Hof equation.

In relation to the viscosity of water, I found an interesting way of experiencing surface tension in water (and to a lesser extent the viscosity) I noticed this in the bath and it's probably nothing new but if you gently place your hand on the water so as not to submerge it and slowly lift it so the water kind of sticks to you (don't know the scientific term) it feels weird but if you keep repeating that process, slowly lowering and raising your hand slightly from the surface of the water for like a minute and then start gently pushing down on the water, keeping your hand flat you'll notice you actually feel the weight of the water resisting which you don't normally.

Funny thing, if you swim, you consider water as a viscous liquid like in the video, most of swimming styles avoid the coming back. We might not consider it viscous or not like a tiny animal, but the liquid doesn't change, just our size and strengths

Dunno about daphnia, but from personal experience, cyclopes don't like being under microscope very much, as the lamp warms the water causing them to constantly flee away from your aperture. Makes them kinda hard to observe because of that

At 7:01, the Daphnia stops moving water, looks up at the large particle then restarts the flow.... I find that action very interresting .

If water is so viscous at that scale, can we get footage of water being poured from one Daphnia-sized beaker into another?

I liked this video, and the main things you had to say were correct, but fish swimming isn't time reversible. Fish swim like snakes slither, a wave traveling front to back.

i feel too emotionally connected to this daphnia now :s

Steve Mould... what a great name for a microscopist.

I've noticed that water on a tabletop behaves as though it were more viscous than bulk liquid, probably because so much of the water is near the adhesion layer where flow can't take place. Might the thin layer of water on a microscope slide feel much more viscous to a daphnia than the bulk water of a pond or puddle? And do they ever get "stuck" in the boundary layer near objects or at the surface?

So what youre saying is the caffeine test was probably done with hot coffee rather than just straight caffeine so it skewed the results for those who claimed to get a result?

I wonder about the temperature change to their heartbeat. Do they have any sensor that can detect heat and cause a reaction? Or is it purely a chemical reaction change?

it's interesting that about a minute before you mention ethics, I was thinking that he has probably "disposed" them after experiment and it means that microscopic creature is out of gene pool, and then it came to my mind that what is the probability that this daphnia had a mutation that in the long run could have affected their evolution ... and that was when you mentioned you have released them. Thanks for starting the chain of thought, this matters for scientifically looking at things.

@68wayupintheskyftw61

6 жыл бұрын

Mehrad Mahmoudian do you do that Everytime you take a step outside?

@mehrad_ai

6 жыл бұрын

No, but sometimes when I do an experiment in lab this comes to my mind. I think the main plus side of this channel is to make people think and then rethink.

I feel our human ethic is not about the projection of emotional sympathies for subjective states in others, and corresponding fear of doing harms or evils, but in our extension of recognition of life to life as a shared quality of existence, in which do as we would be done by, is guided by acceptance of a living context of which all parts play a part. This is because in psychic-emotional terms - or perhaps in spiritual terms - we set the measure of our receipt by the nature of what we give out. Torture is recognised as a dehumanising influence - and is of course an extreme dissociation from consequence that is not necessarily recognised in the playing out of power over the bodies of others. Loveless sex can also hollow out to mere mechanical attempts to re-enact a sense of life lost. So in our relationship with all living things - and the living world of which they are one with - we can become harmless in intent - within practicalities for simply living the life we are uniquely being. The psyche of Man is currently split upon a predicate of guilt and fear that is then compartmentalised and rationalised under social mores of definition and belief. The guilt for despoiling nature being a current source of political manipulation - on top of an systemically dissociated 'nature'. I call for the nature of a true resonance to align our thought word and deed, rather than systems of repackaging toxic debts into complex instruments of any kind of 'clever thinking'. Remorse is natural to acts of self-betrayal, and calls on immediate re-alignment. But guilt of an irrevocable or uncorrectable act (or negligence) usurps the mind and dissociates its perceptions in the attempt to escape, mitigate, or divert and displace the self-dissonance away from 'self' - while of course projecting this separateness onto Nature or our World - and so for example perceiving the world through fearful associations that then effectively 'program' or condition our thought, attention and response. Humans have developed a 'virtual modelling' of an interpretive 'world' that operates both personal and collective 'subjections'. The mind that sets out with the idea of subjection - ie dominance - is 'alive and well' in the stream of science that seeks to define, predict and control, and so is funded and utilised by that 'drive'. I eat prawns, but I don't subject them to random mutilations or degradations while alive. Is food murder? Or the Gift of the Whole to all its parts (that are never truly apart). The intent to kill has a quality of hatred in it. Acting without love, makes us loveless, and thus disposed to see and expect in like kind.

Steve you are so smart man seriously

I absolutely love that you brought up ethical concerns. Science is cringe worthy to me because the subject is almost never brought up. It's just "we gave some rats a horrible disease and X happened" as if it's no big deal. Sure the daphnia probably can't process pain nor stress, but a cat can, so where is that line? Can a mosquito? Can a halibut? Can sea horse? It's a really important debate that never seems to happen, and when you bring it up so many people get triggered for some strange reason. Just look at how people will send death threats if you kick a dog...while eating a factory farmed KFC breast. Other than that, the concept of the differences in fluid dynamics with respect to scale is fascinating. Subscribed.

Just so you know Steve, the part were you start flapping your hand to demonstrate the fish fin and its reversibility, you did the same flapping motion twice, you didn’t reverse it. You started with your hand going forward first, same the second time😅

My rule of thumb is that if you have

@RealUlrichLeland

6 жыл бұрын

Can I still have your sympathy? I've only got around 7000 atm, but I used to have around 12k.

@3_up_moon

6 жыл бұрын

MisterPotatoHands plants can recognize that something is happening to or around them. Neurons are overrated. Wait, plants don't have any neurons, right?

@crackedemerald4930

6 жыл бұрын

RDR technically not... Although some species can be considered neurons in their environment

@gocrazy432

6 жыл бұрын

Do they experience? Do they have pain receptors? These questions help answer whether they suffer. They might experience hunger and then starvation, they might experience oxygen concentration/suffocation. You might not label it fear but maybe its a type of or degree of anxiety. With any plants inability to move, its ability to sense and react is the baseline for stimulus response. The ability to suffer would lack benefits beyond that life process of stimulus response.

@3_up_moon

6 жыл бұрын

gocrazy432 a plant has been demonstrated to react when someone is going to cut their leaf (anticipate it) and has a greater reaction when the harm is completed. It's pretty incredible.

Are we sure that the heart-beat increase is passive, due to chemical rate changes (trivial solution), and hence approximately doubling for every 10°C? Or could it be an active feedback regulation circuit?

So cool!

No daphnia was harmed during this footage ;-) Nice video, as usual !! Ooops @5:19 you should not say that "viscosity changes with scale", but "effects due to viscosity change with scale"...

Always good but I think this one would have helped if you'd taken a moment to explain viscosity in the same easy to understand way you explained heat. Just saying "water is most viscous to things that are smaller" left me wondering why that is.