to get an ECG which is one of several strategies they could use. (e.g. lately I've been interested in Heart Rate Variability which has gotten me looking at reading heart rate with cameras, radars, pressure gauges, ultrasound, etc.)
navane 4 hours ago [-]
30 BPM at the surface, 4 bpm while diving.
flopsamjetsam 3 hours ago [-]
"Analysis of the data suggests that a blue whale’s heart is already working at its limit, which may explain why blue whales have never evolved to be bigger."
Incredible to think of the volume of all the blood it's pumping around.
tmoravec 3 hours ago [-]
I don't understand how that would limit evolution. Bigger bodies can evolve together with bigger hearts, as already witnessed with the very whales being researched.
observationist 3 hours ago [-]
The volume of blood that needs to be pumped increases e̶x̶p̶o̶n̶e̶n̶t̶i̶a̶l̶l̶y̶ cubically with size, meaning the cells have to do more work, or there have to be more of them. The size of the heart has to match the volume of blood being pumped - if they evolved to be larger, the heart might have to be so big that it creates pathology in other areas, or has to pump so hard it damages tissue, or creates forces so great that veins or arteries collapse or burst.
It's probably not as dramatic an issue as that. It could also be sensory - past a certain size, in order to be sensitive enough to detect damage and deal with normal conditions, it would have to be irritated all the time, or numb to potential hazards.
There are all sorts of second and third order consequences limiting how various vital systems can interplay, so more than likely, it's a combination of a whole bunch of things that subtly limit the overall size to where it's at, and any further increase degrades its abilities to survive.
They're just so huge. Their brains are 4 times larger than a human's brain, but we share a whole lot of structure, from the cellular level to the macro, with two lobes, some shared sulcal features (same folding pattern) which indicates that we likely share enough connectomic structure for the ways in which our brains operate to produce similar conscious experiences. Someday, in the distant future, we should be able to use BCI to feel exactly what it's like to be a blue whale (and vice versa.)
Their brains have similar cortical structure, but even though the brains are about 7 times larger, their cortical surface area is only 2-3 times that of a human. It really puts into context how bizarrely massive our brains are for our relatively tiny size.
For contrast, titanosaur hearts would have been around 500 lbs and up to 6 feet in diameter, and their brains were about the size of a big walnut. These land animals were up to 40m long and 100 tons.
Anyway - physics of tissue and frailties of being made of meat are what keep the whales from getting much bigger.
manwe150 57 minutes ago [-]
But also internal space is increasing cubically—so any reason it couldn’t have mutated to have 2 hearts servicing each side of the body?
You could also claim our bodies have massive surface area, molecularly speaking. We just are factory-configured to not sense things that are too small to matter to ourselves as a whole (like small bugs and below)
inopinatus 1 minutes ago [-]
[delayed]
observationist 46 minutes ago [-]
Klingon whales, now?
There are measurements suited to purpose, then there are "technically you could do that" measurements, and it's the former we'd want to use when measuring what sorts of power and pressure and material properties of the vascular system and cardiac tissue of a whale. Enormous amounts of blood are being pumped around, and I'd have to imagine you're in the million miles of arteries and veins and capillaries ballpark, so there's a lot of pressure holding that mass back.
That'd be a fun model to figure out for a weekend project - what sorts of forces are we talking about - how efficient is it compared to say, a hummingbird, or a human, or an earthworm heart?
fluoridation 1 hours ago [-]
I don't understand how the square-cube law is relevant here. The volume of blood indeed scales cubically with the length, but so does the volume of the heart. Where is the quadratic part of the equation that limits the maximum size of a whale? Why would it not work to take a whale and arbitrarily scale it in photoshop?
Qem 50 minutes ago [-]
> Where is the quadratic part of the equation that limits the maximum size of a whale?
Muscle power output increases with cross section area, ~L^2, not with volume. The heart have no separate power unit. It relies on the same muscle walls that comprise its chambers to power itself.
fluoridation 48 minutes ago [-]
That just means the walls of the heart would need to grow thicker. Are they at the limit already?
Qem 38 minutes ago [-]
Wall thickness increasing by x increases cross section/power by x^2, but also increases chamber volume/workload by x^3. So workload outruns available power. It's because of this people abusing steroids get heart failure eventually.
fluoridation 31 minutes ago [-]
>chamber volume/workload by x^3. So workload outruns available power.
What do you mean by workload? Are you referring to the oxygen cost per stroke, or what?
frotaur 3 hours ago [-]
Nitpick, but the volume increases cubically (it scales with volume), not exponentially.
observationist 2 hours ago [-]
Thank you, I'll correct that. I was thinking inverse square law, then instead of asking an AI like a good nerd, I just winged it.
setsewerd 35 minutes ago [-]
Some might say you're a purist in that regard
Side note, would positing an argument online without doing an AI fact check first be considered rawdogging your answer?
It seems fitting.
JumpCrisscross 3 hours ago [-]
> don't understand how that would limit evolution
Cardiac tissue is a surface. Blood is a volume. I think they’re saying blue whale hearts are near the largest current biology can evolve. Which is interesting because it suggests if we could e.g. engineer whales with carbon-fiber hearts or whatever, they’d evolve to grow even bigger.
observationist 3 hours ago [-]
Blackheart the whale, lurking the oceans, ever devouring and growing. I think you've got a good Lovecraft/Pirates of the Carribean/Black Mirror mashup premise here.
fluoridation 58 minutes ago [-]
Cardiac tissue is also a volume. It can be thicker or thinner as the animal requires.
robotnikman 17 minutes ago [-]
Or if not bigger hearts, what about multiple hearts?
kadoban 2 hours ago [-]
> Bigger bodies can evolve together with bigger hearts, as already witnessed with the very whales being researched.
Hm? Aren't blue whales the biggest animals to ever have lived that we know of?
BurningFrog 47 minutes ago [-]
At the risk of being annoying, I'm pretty sure they have evolved to be bigger quite a lot, until they reached their maximum viable size.
steve_adams_86 2 hours ago [-]
These are peak free diver goals. Though I'm sure I'd be guaranteed to black out at 4bpm, haha. Incredible.
arunc 3 hours ago [-]
> Looking at the big picture, the researchers think the whale’s heart is performing near its limits. This may help explain why no animal has ever been larger than a blue whale – because the energy needs of a larger body would outpace what the heart can sustain.
Fascinating to learn such details!
mr_mitm 3 hours ago [-]
Could an animal have several hearts?
djtriptych 3 hours ago [-]
yes. I know octopuses and squids have three hearts. Just looked it up and it seems no mammal has more than one heart.
joecool1029 2 hours ago [-]
I do wonder if those animals have things like valves in their veins, as I understand it if the circulatory system wasn't as complex as it is, heart would have to pump a lot harder to move the volume it does. This isn't an area I know much of anything about, I just know veins have valves and can expand and contract to different stimuli much as a heart can... so even though mammals have one heart it's not like the rest of the system is a static not helping to pump blood.
raldi 4 hours ago [-]
Anyone got a direct link to or time index of the recording? I skipped around the video on the linked page but it was all music.
nsbk 2 hours ago [-]
I watched the whole video and there is no heartbeat sound, which is what I was expecting as well. I think that they recorded the signal, not the sound that the heart makes when pumping blood.
krunck 4 hours ago [-]
A Whale's tachycardia is my bradycardia. Huh.
bob1029 3 hours ago [-]
There are documented cases of perfectly healthy humans with resting heart rates under 30bpm.
"The Etruscan shrew has a very fast heart beating rate, up to 1511 beats/min (25 beats/s) and a relatively large heart muscle mass, 1.2% of body weight."
(to illustrate - machine guns typically do 600-900 rounds/min)
I wonder whose muscle fiber is stronger per unit mass - the whale's or the shrew's...
Rendered at 00:04:46 GMT+0000 (Coordinated Universal Time) with Vercel.
https://www.pnas.org/doi/10.1073/pnas.1914273116
to get an ECG which is one of several strategies they could use. (e.g. lately I've been interested in Heart Rate Variability which has gotten me looking at reading heart rate with cameras, radars, pressure gauges, ultrasound, etc.)
Incredible to think of the volume of all the blood it's pumping around.
It's probably not as dramatic an issue as that. It could also be sensory - past a certain size, in order to be sensitive enough to detect damage and deal with normal conditions, it would have to be irritated all the time, or numb to potential hazards.
There are all sorts of second and third order consequences limiting how various vital systems can interplay, so more than likely, it's a combination of a whole bunch of things that subtly limit the overall size to where it's at, and any further increase degrades its abilities to survive.
They're just so huge. Their brains are 4 times larger than a human's brain, but we share a whole lot of structure, from the cellular level to the macro, with two lobes, some shared sulcal features (same folding pattern) which indicates that we likely share enough connectomic structure for the ways in which our brains operate to produce similar conscious experiences. Someday, in the distant future, we should be able to use BCI to feel exactly what it's like to be a blue whale (and vice versa.)
Their brains have similar cortical structure, but even though the brains are about 7 times larger, their cortical surface area is only 2-3 times that of a human. It really puts into context how bizarrely massive our brains are for our relatively tiny size.
For contrast, titanosaur hearts would have been around 500 lbs and up to 6 feet in diameter, and their brains were about the size of a big walnut. These land animals were up to 40m long and 100 tons.
Anyway - physics of tissue and frailties of being made of meat are what keep the whales from getting much bigger.
You could also claim our bodies have massive surface area, molecularly speaking. We just are factory-configured to not sense things that are too small to matter to ourselves as a whole (like small bugs and below)
There are measurements suited to purpose, then there are "technically you could do that" measurements, and it's the former we'd want to use when measuring what sorts of power and pressure and material properties of the vascular system and cardiac tissue of a whale. Enormous amounts of blood are being pumped around, and I'd have to imagine you're in the million miles of arteries and veins and capillaries ballpark, so there's a lot of pressure holding that mass back.
That'd be a fun model to figure out for a weekend project - what sorts of forces are we talking about - how efficient is it compared to say, a hummingbird, or a human, or an earthworm heart?
Muscle power output increases with cross section area, ~L^2, not with volume. The heart have no separate power unit. It relies on the same muscle walls that comprise its chambers to power itself.
What do you mean by workload? Are you referring to the oxygen cost per stroke, or what?
Side note, would positing an argument online without doing an AI fact check first be considered rawdogging your answer?
It seems fitting.
Cardiac tissue is a surface. Blood is a volume. I think they’re saying blue whale hearts are near the largest current biology can evolve. Which is interesting because it suggests if we could e.g. engineer whales with carbon-fiber hearts or whatever, they’d evolve to grow even bigger.
Hm? Aren't blue whales the biggest animals to ever have lived that we know of?
Fascinating to learn such details!
https://www.guinnessworldrecords.com/world-records/lowest-he...
https://en.wikipedia.org/wiki/Etruscan_shrew
"The Etruscan shrew has a very fast heart beating rate, up to 1511 beats/min (25 beats/s) and a relatively large heart muscle mass, 1.2% of body weight."
(to illustrate - machine guns typically do 600-900 rounds/min)
I wonder whose muscle fiber is stronger per unit mass - the whale's or the shrew's...