Oxygen chambers = size ?

[Talkenlate04]

What does that have to do with anything in this thread? :?

 

[Travis K]

ha, yeah, i guess i kinda left the idea of the OP and was talking more about cross breeding and such...

this is what got me thinking about that.

 

[Talkenlate04]

Oh. lol.
Well I am not making this thread about my ya............ you know.

 

[DrAce]

There is another limitation on spider size - the exoskeleton. There is only so much weight that the chitinous exoskeleton can hold up - without thinkening beyond it's own weight.

You'll note that the largest creatures with these external skeletons are all aquatic... there's more support from the water to allow that size.

Also, there's only so much an open blood system can achieve, if I recall correctly.

Nothing is as simple as 'scaling up' an organism.

Also, increasing the oxygen supply dramatically DECREASES lifespan. Oxidative processes set in and basically destroy the organism quickly.

 

[Travis K]

There is another limitation on spider size - the exoskeleton. There is only so much weight that the chitinous exoskeleton can hold up - without thinkening beyond it's own weight.

You'll note that the largest creatures with these external skeletons are all aquatic... there's more support from the water to allow that size.

Also, there's only so much an open blood system can achieve, if I recall correctly.

Nothing is as simple as 'scaling up' an organism.

Also, increasing the oxygen supply dramatically DECREASES lifespan. Oxidative processes set in and basically destroy the organism quickly.

Hmm, http://www.arachnoboards.com/ab/showthread.php?t=119451&highlight=coconut+crab

Now a T that size would be very impresive.

[YOUTUBE]LpsG7CI3RAA[/YOUTUBE]

[YOUTUBE]rvTFaTDPMSo[/YOUTUBE]

 

[DrAce]

Hmmmmm... (my Hmmm was bigger than your Hmmm) The Coconut crab lives to get to about 3' in legspan... wieghing in at 4 kg-ish. From what I understand, they spend months underground in burrows allowing time for their chiton to harden during moults - ecdysis in a creature of that size would in itself be a particularly taxing process.
Now think about the process of moulting itself. What, exactly, holds the animal together BEFORE that moult has formed? They are basically a little sac of skin. That sac of skin has got to hold some 10 lbs of crab soup inside WITHOUT SIGNIFICANT DEFORMITY while the shell hardens.
There's another good problem. As an object increases in volume, it's weight goes up by a cubic relationship. 10cm x 10 x 10 = 1 kg of water. 20 cm x20 x 20 = 8 kg of water. A structure holding that weight doesn't need to DOUBLE in size, it needs to CUBE it's size. So the legs of such a creature need to scale differently to the body. Oxygen alone won't do that... you need genetic changes for that to happen. It's pretty basic civil engineering. You can't JUST make things bigger. Forces don't work like that!
Then you gotta have muscles to move an object that size... and muscles don't just scale. Then you have to have a blood system to deliver the oxygen needed to those muscles as fast as they use them to move, then you have to have a nervous system to deliver the messages needed in synch, and that needs a blood supply as well...

It's really not as simple as it sounds.

EDIT: I just found this website, which basically tells you what I just told you... but with pretty graphics and animation.

 

[Steven Valys]

I just found this website, which basically tells you what I just told you... but with pretty graphics and animation.

That pretty much sums it all up.