How big could spiders get?

[Zablorg]

Now, I know that it's totally improbable for giant spiders to evolve, but how big could they conceivably become before that odd little respiratory system of theirs stops working? As I recall there would also be some problems with bugs becoming huge just because their body proportions are designed for smaller loads, so for the sake of argument(?) we say that their body parts are resized accordingly.

[CJvR]

Fairly large.

There was some huge bugs around very early in the evolution of life, naturally the competition was lower and the oxygen level was much higher but bugs can get quite big before they suffer from structural collapse.

http://www.rxpgnews.com/evolution/Giant ... 5059.shtml

[Ted C]

I believe there's an existing species of tarantula with a leg-spread of something like 12 inches.

[Ted C]

Ah, yes, the Goliath Bird Eater.

http://www.extremescience.com/BiggestSpider.htm

[Frank Hipper]

Despite some recent television documentaries to the contrary, the Goliath Bird Eater is the largest spider on record.

[CJvR]

I have seen a spider in that size class live once. Huge beast, big enough to cover a dinner plate no problem - and equipped with half inch long fangs!!! Im glad it was behind glass of the thicker variety.

[Alyrium Denryle]

Now, I know that it's totally improbable for giant spiders to evolve, but how big could they conceivably become before that odd little respiratory system of theirs stops working? As I recall there would also be some problems with bugs becoming huge just because their body proportions are designed for smaller loads, so for the sake of argument(?) we say that their body parts are resized accordingly.

There used to be giant arthropods over a meter in length. Honestly the size of insects and arachnids now is more O2 limited than load limited.

[Darth Wong]

Structural limits come into play when you start talking about giant horror-movie insects, not insects the same size as a large dog.

[Sea Skimmer]

I do believe the largest arthropod we’ve ever found in the fossil record was about 9.5 feet long.

[The Spartan]

I do believe the largest arthropod we’ve ever found in the fossil record was about 9.5 feet long.

Wasn't that aquatic though?

[Sea Skimmer]

Wasn't that aquatic though?

Seems you are right, it was a sea scorpion, and in fact the modern Japanese spider crab actually has greater size in term of dimensions (leg span) though significantly lower mass. Quirky looking thing, very rightly named after Nippon.

[Elfdart]

I remember reading somewhere that the exoskeleton has limits as to how much it can support, and anything above the size of a large dog was unlikely.

[NoXion]

Would an arthropod be able to evolve lungs more more like that of the vertebrates? If not, would lungs "work" if they were hacked in with some sort of genetic engineering?

Just wondering if there was a way of having large arthropods that don't need buttloads of oxygen in comparison to vertebrates.

[Tasoth]

Would an arthropod be able to evolve lungs more more like that of the vertebrates? If not, would lungs "work" if they were hacked in with some sort of genetic engineering?

Just wondering if there was a way of having large arthropods that don't need buttloads of oxygen in comparison to vertebrates.

The the problem with that, if I'm remembering my Zoology right, is that arthropod spiracles take in oxygen along the entire length of their body. I would suppose slapping lungs into an insect would be rather inefficient as they don't have a skeletal frame that makes a neat little box to hold them in and prevent them from being folded over by body movements.

[Alyrium Denryle]

I do believe the largest arthropod we’ve ever found in the fossil record was about 9.5 feet long.

Wasn't that aquatic though?

Yes, but some could crawl about on land that were almost as big

[Alyrium Denryle]

Would an arthropod be able to evolve lungs more more like that of the vertebrates? If not, would lungs "work" if they were hacked in with some sort of genetic engineering?

Just wondering if there was a way of having large arthropods that don't need buttloads of oxygen in comparison to vertebrates.

The the problem with that, if I'm remembering my Zoology right, is that arthropod spiracles take in oxygen along the entire length of their body. I would suppose slapping lungs into an insect would be rather inefficient as they don't have a skeletal frame that makes a neat little box to hold them in and prevent them from being folded over by body movements.

that and they would need an closed circulatory system, with actual blood instead of haemolymph... and a way to expand the lungs...

[Zor]

The biggest Terrestrial arthropods in the Carboniferous age were rather large, for glorified millipedes.

Zor

[The Spartan]

I do believe the largest arthropod we’ve ever found in the fossil record was about 9.5 feet long.

Wasn't that aquatic though?

Yes, but some could crawl about on land that were almost as big

Like Zor's millipedes? What about something with a more "traditional" spider body? Do you happen to know of any monstrously-sized, prehistoric ones?

Or is the Goliath Bird Eater the largest we know of?

[Alyrium Denryle]

Wasn't that aquatic though?

Yes, but some could crawl about on land that were almost as big

Like Zor's millipedes? What about something with a more "traditional" spider body? Do you happen to know of any monstrously-sized, prehistoric ones?

Or is the Goliath Bird Eater the largest we know of?

Not sure. Some of them got pretty damn big, but I am having difficulty finding info on the extinct arachnid suborders... There were some HUGE insects in bygone days though