31 replies to this topic

[PlanB]

Insanity, on 20 December 2012 - 09:00 PM, said:

Lesser gravity was not the reason for larger insects and other arthropods, as Earth's gravity has remained mostly constant.  In those times though it is largely believe the oxygen content of Earth's atmosphere was higher.  Currently it is about 21% of the atmosphere, and may have been 50% more, or ~40%, hundreds of millions of years ago.  This alone would allow them to grow larger as the external oxygen content was higher, thus diffusing more into their bodies without any extra effort.

Ah, well thanks for clearing that up. My understanding was that an older earth had reduced gravity and that combined with the oxygen content accounted for the larger arthropods.

[Insanity]

It could not have been a giant spider in regards to what we understand about spider anatomy, physiology and how how we classify species.  If it was something physically similar to a spider, but perhaps possessed lungs to permit the larger sizes, it really would not be a spider, and would likely be classified differently.

I am not certain if the exoskeleton weight or strength is the real limiting factor in their sizes, but their respiratory and circulatory most likely are.  Change those to match that of a terrestrial vertebrate, you could have a very larger spider roaming around looking for dogs to eat.  That would be a significant change in physiology for arthropods though.

[Insanity]

PlanB, on 20 December 2012 - 09:07 PM, said:

Ah, well thanks for clearing that up. My understanding was that an older earth had reduced gravity and that combined with the oxygen content accounted for the larger arthropods.

The gravitational field of an object is related to its mass and radius, and while those of the Earth's may have changed somewhat over the millions of years, probably not significantly enough to account for a noticeable change.

[QuiteContrary]

And arthropods today grow larger when put in oxygen rich environments. But not science fiction size.

[Boribel]

This one is  big.

Edited by Boribel, 20 December 2012 - 09:30 PM.

[QuiteContrary]

gotta know how to handle them, it is not hard to tick off either T. blondi or T. sturmi!
Both often confused with each other even in the hobby.
And tarantulas are so vulnerable if they fall, due to their anatomy as well.
So handling is not something to take lightly.

Edited by QuiteContrary, 20 December 2012 - 11:23 PM.

[Orcseeker]

Even during the times of a higher percentage of oxygen, spiders didn't reach as epic proportions as insects like the dragonfly or millipede did. The Goliath bird eating spider, correct me if I'm wrong, is the largest to have ever existed.

Given our oxygen levels are a lot lower, let alone in those conditions spiders not being overly huge let alone anywhere near the size of these ones in the Congo pretty much highlights the fact that this may just simply be one of those "mysterious Congo" stories.

[JGirl]

if i saw a giant spider my first inclination would be to hop on its back and ride that puppy!

Edited by JGirl, 21 December 2012 - 01:12 AM.

[PlanB]

Orcseeker, on 21 December 2012 - 01:04 AM, said:

Even during the times of a higher percentage of oxygen, spiders didn't reach as epic proportions as insects like the dragonfly or millipede did. The Goliath bird eating spider, correct me if I'm wrong, is the largest to have ever existed.

Given our oxygen levels are a lot lower, let alone in those conditions spiders not being overly huge let alone anywhere near the size of these ones in the Congo pretty much highlights the fact that this may just simply be one of those "mysterious Congo" stories.

You may be right. Goliath bird eaters are probably the biggest in terms of girth, but I think the huntsman slightly beats it in terms of leg span. A fossil thought to be the biggest spider ever discovered and called megarachne ended up being that of a sea scorpion.

A possible contender to the goliath bird eater is another South American tarantula called a chicken eating spider that was recently discovered. So far, no condor-eating spiders.

[R4z3rsPar4d0x]

Can someone post a picture of the Bird eating spider? Id like to see how big they get

[mygrassisgreen]

[Orcseeker]

PlanB, on 21 December 2012 - 02:00 AM, said:

You may be right. Goliath bird eaters are probably the biggest in terms of girth, but I think the huntsman slightly beats it in terms of leg span. A fossil thought to be the biggest spider ever discovered and called megarachne ended up being that of a sea scorpion.

A possible contender to the goliath bird eater is another South American tarantula called a chicken eating spider that was recently discovered. So far, no condor-eating spiders.

I havent seen a huntsman that big yet. I also ward about the Megarachne. First thing to come to mind when i saw this thread on big spiders was the "Walking with Monsters" episode showing an apparent species of Mesothelae. Purportedly the Megarachne which was revealed to be the sea scorpion after production on the series began. No such spider has been found to exist.

Interesting news on the new spider, I imagine a chicken eating spider these days would need to be a bit bigger.

[the L]

Cynical Sounds, on 19 December 2012 - 05:09 PM, said:

Yep impossible.

Spiders dont have lungs and absorb all there oxygen through an area on there abdomen called a book lung. http://en.wikipedia.org/wiki/Book_lung

Basically a spider that size wouldn't be able to get enough oxygen to internal tissue that far from its book lungs and it cells would become oxygen starved and die.

Thats pity. I would like that there are giant spiders.

[Orcseeker]

the L, on 23 December 2012 - 01:19 PM, said:

Thats pity. I would like that there are giant spiders.

Impossible given the current anatomy of the currently discovered species. I've seen flying spiders in an Asian country first hand. There is so much out there we would never think possible which are.

This could be likened to the platypus. Professors and biologists thought it was a construct made of other animals stitched together. Turned out it was a legitimate species.

Edited by Orcseeker, 23 December 2012 - 03:32 PM.

[R4z3rsPar4d0x]

WOW that bird eating spider is HUGE, If I ran into that I would just let it be

Edited by R4z3rsPar4d0x, 24 December 2012 - 08:10 PM.