Another review from your favorite MB Troll

[Chainsawmidget]

True. That's one of the things limiting the size of a lot of creepy crawlies. Their respiratory systems are not efficient enough to sustain a larger body. Not sure whether the bugs in the Carboniferous Period were still limited by the available oxygen, or whether they'd run up against the weight limit of an arthropod exoskeleton, which really can't support anything too big on land. Could be that any spider with a body bigger than roughly the size of your head wouldn't be able to stand. I know for sure that a giant one would collapse under its own weight.

But that would make for a really short movie. I suppose you could make a feature-length movie in which the spider mutates, grows to about the size of a Golden Retriever, can no longer move and starts to suffocate. Then you pad out the run time with an hour of vultures pecking at the poor thing.

Get a mediocre level celebrity attached to this and I think you could sell the idea to Hollywood!

[WyreWizard]

All that oxygen during the Carboniferous period was a leftover from the times when stromatolites ruled the surface.  You see when life began, it was all underwater.  The atmosphere at the time was mostly methane,with small amounts of nitrogen and other inert gases.  Single celled organisms were the standard.  These were in Earth's oceans.  Then came Earth's worst ice age, otherwise known as Snowball Earth.  During this period, snow and ice covered all of the Earth's surface, reflecting all sunlight back into space.  There wasn't any carbon dioxide in the atmosphere to hold it in.  Life was able to hold on in the oceans greatest depth near volcanic vents where it evolved into multicellular creatures.  The Snowball Earth was brought to an end when the Earth responded with thousands of volcanoes erupting from the ground filling the mostly methane atmosphere with carbon dioxide.  Over the next few million years, the snow and ice melted and Earth was a green planet instead of white.  However, there was no oxygen in the atmosphere yet.  The atmosphere was methane and carbon dioxide.  Then stromatolites evolved and converted the carbon dioxide into oxygen over hundreds of millions of years.  Within that period, vertebrates evolved and animals were moving closer to the oceans surface.  They eventually ventured onto land.

[Intangible Skeleton]

I freakin' love this film! It's hilarious and badass in that way that only 80's b-sci-fi/action could be. The title of the movie is there entirely so that Dolph Lundgren can make his witty prehumous retort. It doesn't even make any sense!

[AndyC]

All that oxygen during the Carboniferous period was a leftover from the times when stromatolites ruled the surface.  You see when life began, it was all underwater.  The atmosphere at the time was mostly methane,with small amounts of nitrogen and other inert gases.  Single celled organisms were the standard.  These were in Earth's oceans.  Then came Earth's worst ice age, otherwise known as Snowball Earth.  During this period, snow and ice covered all of the Earth's surface, reflecting all sunlight back into space.  There wasn't any carbon dioxide in the atmosphere to hold it in.  Life was able to hold on in the oceans greatest depth near volcanic vents where it evolved into multicellular creatures.  The Snowball Earth was brought to an end when the Earth responded with thousands of volcanoes erupting from the ground filling the mostly methane atmosphere with carbon dioxide.  Over the next few million years, the snow and ice melted and Earth was a green planet instead of white.  However, there was no oxygen in the atmosphere yet.  The atmosphere was methane and carbon dioxide.  Then stromatolites evolved and converted the carbon dioxide into oxygen over hundreds of millions of years.  Within that period, vertebrates evolved and animals were moving closer to the oceans surface.  They eventually ventured onto land.

Your point being?

[WyreWizard]

Your point being?

My point?  Well in one of your posts, you seemed think that the fact the atmosphere during the carboniferous period have a high oxygen content was just a theory and I was just saying why it was and what caused it, that's all.

Have you ever seen that documentary called the Future is Wild?  Well that show says that 200 million years from now there will be a giant insect called the falcon fly which is really a wasp and it'll have a 2 or 3 foot wingspan.  That tells me that 200 million years from now, Earth's atmosphere will be similar to what it was during the carboniferous period.  Of course, that is just a theory seeing as how its in the future and hasn't happened yet.

[AndyC]

Not sure whether the bugs in the Carboniferous Period were still limited by the available oxygen, or whether they'd run up against the weight limit of an arthropod exoskeleton, which really can't support anything too big on land.

I was questioning whether they still had room to grow if there were even more oxygen, or whether they'd reached the structural limit of their bodies. The existence of creatures such as Arthropleura, over six feet long, but spread out over a longer body with more legs, suggests to me that weight was the limiting factor, and those spiders and dragonflies were as large as they could get. Today, their simple respiratory systems keep arthropods small, but the oxygen content of the carboniferous allowed them to max out what their bodies could support. More oxygen would not have made them any bigger. It was more a matter of figuring out how big a spider could realistically get.

And actually, a quick Google tells me spiders didn't even get that big. Apparently, the giant Carboniferous spider was a misidentified species of sea scorpion - basically a big prehistoric crab.
http://menmedia.co.uk/manchestereveningnews/news/s/146/146372_spider_as_big_as_a_dog_didnt_exist.html

[WyreWizard]

Sea Scorpions are an entirely different matter.  They grew so big because they were underwater arthropods.  You see, soft-bodied creatures grow bigger underwater than they do on land because the buoyancy of water gives their bodies better support and a greater concentration of oxygen than in the air.  I mean face it, oxygen is thicker underwater than it is on land.  I mean, you have water molecules which are one part hydrogen to two parts oxygen sliding over each other.  But in the air, O2 and O3 molecules aren't touching each other so they form a gas.  The only thing bounding them in close proximity is gravity.
     I remember seeing one documentary on Animal Planet about prehistoric sea life.  It covered the first fish, sea scorpions of various species and straight nautiloids.  Sea Scorpions came in many species, some as small as 2 feet and other growing up to 10 feet in length.  Believe it or not, this documentary actually showed sea scorpions venturing onto land!  They ventured onto land because their prey crossed land bridges to reach their spawning grounds.  I don't know if this was possible or not.  I mean the shells of these sea scorpions may have acted like built in scuba equipment.  Or they may have been semi-amphibious.  I don't know, what do you think?

[AndyC]

So, now you're just giving spontaneous lectures for no reason? That's bizarre, and kind of sad.