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.<p>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.<p>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.<p>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.)<p>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.<p>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.<p>Anyway - physics of tissue and frailties of being made of meat are what keep the whales from getting much bigger.
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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?<p>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)
Klingon whales, now?<p>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.<p>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?
A binary vascular system? Do you want regenerating whales in the time vortex?
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?
> Where is the quadratic part of the equation that limits the maximum size of a whale?<p>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.
Nitpick, but the volume increases cubically (it scales with volume), not exponentially.
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.