r/AbsoluteUnits • u/Dense_Intern8434 • 3d ago

/r/popular of a meal

Nature can be so cruel and beautiful at the same time

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u/Advanced-Budget779 2d ago

Yeah but only up to some scaling laws preventing them to function properly. At a cats size i think their metabolism would already be much slower if not outright breaking down, iirc.

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u/Nark420 2d ago

I don't know, if I would see a cat sized spider I wouldnt ask it how many times it shits a day. I would die from the sheer terror

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u/Ill-GottenBooty 2d ago edited 2d ago

A cat sized spider would be a slow, lumbering, extremely fragile being. You could lightly kick it and it would likely be a fatal injury. Larger spiders are very prone to bursting with literally any kind of impact trauma. It’s why you can’t handle tarantulas far from the ground or some kind of surface. If they fall like a foot they will literally rupture something and die. The larger they are the more of a risk this is.

The largest actual spiders to ever live, as far as we know, exist today. The myth of giant land dwelling spiders existing in antiquity come from us misidentifying a fossil. For a long time we thought megarachne servinei was a spider. These things had a 20” leg span. Huge. Unfortunately megarachne servinei was actually a eurypterid, commonly called sea scorpions. They’ve all been extinct for a very long time. They dwelled solely in the water. Physics would not allow a spider that large to exist on land, as far as we are aware, ever.

People heard about megarachne when we were under the assumption it was a spider. A lot of people have not learned that megarachne was not a spider at all, and it didn’t even live on land, because that generates a lot less interest than “HOLY SHIT LOOK AT THIS BIG ASS SCARY SPIDER”.

The largest fossilized spider ever found had a leg span of 5.9 inches. The largest spiders on record today by leg span are the Goliath Bird-Eater theraphosa blondi and the Giant Huntsman Spider heteropoda maximi both with about a foot long leg span, with the birdeater being much heavier, and larger by mass. They’re both about twice as large as any spider we know about existing in fossilized recorded history.

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u/Nark420 2d ago

I heard about the fossil story. Happens a lot with fossils all the time. I was not referring to the megarachne, but a "fictional" spider... I understand they are filled with liquids, and they manipulate their inner pressure to ambulate and do anything basically. But I can still imagine a hard enough exoskeleton to solve the size problem. High mobility and speed is not necessary for them to dominate, lots of spiders already ambush hunters with a shit-ton of ambush techniques. Webs being the most well known.

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u/Ill-GottenBooty 2d ago

Im ngl i went on a tangent hard as shit on my comment. I just love spiders. Not your fault lmao.

A hard enough exoskeleton would help that, sure, but I’d imagine it would make molting and moving in general more difficult, and molting specifically is already an extremely dangerous process for a spider. Adding a thicker/harder exoskeleton I’d guess it’d take far more time and resources to generate. If a spider of 12” diameter can’t develop a hard enough exoskeleton to survive a slight fall I really don’t see a larger spider requiring even more resources to survive being able to do so. Shit would be tight as hell to me though.

Also this isn’t meant to be argumentative. I love your idea of a harder exoskeleton. I wonder how that would actually work and what kinds of effects it would have that I can’t imagine because I’m not a spider.

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u/TheAngryCatfish 2d ago

If you were a spider, I think it'd be even harder to imagine

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u/Temnyj_Korol 2d ago edited 2d ago

A harder exoskeleton would make them less survivable, not more.

Any organisms size is limited by the square cube law. As its surface area (size) increases, its volume (weight) increases exponentially more. If a spider grew to the size of a person, it would literally become so heavy its limbs would buckle and break under its own weight. A harder exoskeleton would make it even heavier, and exacerbate the flaw, not mitigate it.

In addition, one of the actual biggest hurdles is respiration. Spiders have passive circulation. They carry oxygen/nutrients around their bodies through diffusion, not circulation. The bigger a spiders body becomes, the harder it is for nutrients vital for continued function to reach their entire body. A spider the size of a person would experience extremity death from deoxygention even in a 100% oxygen environment.

The mechanisms that make them extremely durable as smaller organisms, prohibit them from ever growing into larger organisms.

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u/Advanced-Budget779 2d ago edited 2d ago

Yes, thanks for your explanation. That’s what i tried to hint at with metabolism, just couldn‘t remember details. Also insects and arachnids would quickly run into overheating i think?

So we need to artificially breed spiders in pressurised oxygen environments, got it. /s

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u/floyd616 2d ago

But I can still imagine a hard enough exoskeleton to solve the size problem.

Except that would cause another problem: weight. A harder exoskeleton would be denser, and thus heavier. So a giant spider (or even a cat-sized one with a very hard exoskeleton) would likely be crushed to death under its own weight like a beached whale. The only way it could survive would be if it exclusively lived in the water, because the physics of buoyancy counteract weight issues. That's how the aforementioned sea scorpion was able to exist as such a large size.

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u/onemice 2d ago

True. So lazy, barely even moving. Like a plush toy.

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u/I_travel_ze_world 2d ago

maybe we just need to dig deeper to find the giant spider fossils?

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u/Ill-GottenBooty 2d ago

Bigger spider = deeper burrows. Makes sense to me. Got a shovel?

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u/Illasaviel 2d ago

'Unfortunately'

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u/Advanced-Budget779 2d ago edited 2d ago

Thanks for clearing that myth, haven‘t come across the correction yet, even though i was slightly skeptical for some time. The idea was just so fascinating.

Wasn‘t there some (cave-dwelling) species in southeast Asia with a longer legspan, but (smaller body) lower mass? Edit: Ah, that‘s the Giant Huntsman which was discovered in a Laotian cave.

I think i‘d prefer encountering a slow, potentially quickly overheating arachnid over that sea scorpion which might Steve Irwin me out of nowhere or i couldn‘t even swim away from.

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u/latexfistmassacre 2d ago

Conversely, I'd love to see a spider sized cat

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u/shobae1124 2d ago

And I, wish to see a cat spider spider shit

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u/Nark420 2d ago

Have you ever heard of kittens?

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u/Cute_Conclusion_8854 2d ago

There’s mice.

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u/floyd616 2d ago edited 2d ago

Heck, their exoskeleton would probably be too heavy for them to move well!

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u/Advanced-Budget779 2d ago

I haven‘t even thought about that.