More Oxygen = ?

[Aztek]

Does anyone have anyarticle about from where tarantulas came? I mean, they aren't as old as gian scorpions, and i don't know even if giant scorpions are related to modern scorpions.

And i hear that too. If you get the biggest blondi in the world, it may be the biggest spider EVER!!!!

Scorpions>Tarantulas

 

[Radamanthys]

Scorpions>Tarantulas

Didn't answered my question

 

[Arachn'auQuébec]

http://en.wikipedia.org/wiki/Megarachne

there you go, this is no peer reviewed study, but megarachne is an ancient genus about wich you should find some info on many different websites. 3' legspan, a huge carboniferous era aranea. In order for a blondi to be arguably the biggest spider ever, it would have to be at least 3 times the size of the biggest ever discovered...

I don't know about you guys, but at 6'4", I wouldn't feel safe about a 3' spider in my environment... I have seen many of my spiders attack preys twice their size... A defensive bite from a 6" spider is one thing, but a (3')spider hanging on and injecting all its venom in the intention to digest your tissues as it pulls you with 8 legged torque to its burrow kind of freaks me out

 

[Travis K]

Somewhere a while ago on the internet I read that animals way back when were larger due to the earth having higher oxygen levels (does that make sense?) than it does today.

I really don't know anything about this so sorry if this topic is completely stupid, but If that is true has anyone tested this on any of their T's / other inverts? =P

and I have also read that O2 levels were much lower in the ancient past.

 

[Travis K]

gotta love searching

“We saw something really different,” Lyons said. “We saw very rapid isotopic variability, which suggests there wasn't much sulfate in the early ocean and that oxygen in the atmosphere remained comparatively low for more than 80 percent of Earth's history."

http://www.sciencedaily.com/releases/2004/10/041025115640.htm


Here is a neat paper that sugest that O2 levels haven't really increased or decreased that much once fauna appeared on the scene. http://www.sep.org.uk/catalyst/articles/catalyst_18_4_355.pdf
-see the graph on page 18

 

[wedge07]

http://en.wikipedia.org/wiki/Megarachne

there you go, this is no peer reviewed study, but megarachne is an ancient genus about wich you should find some info on many different websites. 3' legspan, a huge carboniferous era aranea. In order for a blondi to be arguably the biggest spider ever, it would have to be at least 3 times the size of the biggest ever discovered...

Megarachne was later found to be a type of ancient scorpion, making T. blondi still the largest spider. Mesothelae another ancient spider was never found in sizes larger than the blondi and looks nothing like megarachne. Did you even read your own link? It says in the link that megarchne was incorrectly described as a giant spider.

 

[Mushroom Spore]

Did you even read your own link? It says in the link that megarchne was incorrectly described as a giant spider.

My link was about this very creature too. Sorry guys, Megarachne was never a spider or even an arachnid. People who weren't arachnid experts just couldn't tell the difference.

It was more like a big lobster. "Sea scorpions" aren't even scorpions. http://en.wikipedia.org/wiki/Eurypterid

 

[Arachn'auQuébec]

Megarachne was later found to be a type of ancient scorpion, making T. blondi still the largest spider. Mesothelae another ancient spider was never found in sizes larger than the blondi and looks nothing like megarachne. Did you even read your own link? It says in the link that megarchne was incorrectly described as a giant spider.

hehe...oops sry about that guys

 

[zwd22]

In one of the last threads on this someone brought up the point of oxygen being corrosive, so theoretically an atmosphere with more oxygen would kill modern-day T's, or at least give them a shorter lifespan. Perhaps the huge T's of the past had ways of dealing with this, but that adaptation is most likely lost in our T's that do not need it.

Actually... oxygen is by no means corrosive, as in acidic. If you mean it can eat away at things it's because that it is a powerful oxidative agent and thus causes metals to lose their electron becoming ions which then goes on to form oxides(also known as rusting). If anything Carbon dioxide is acidic because it forms carbonic acid by interacting with water.

 

[gambite]

Actually... oxygen is by no means corrosive, as in acidic. If you mean it can eat away at things it's because that it is a powerful oxidative agent and thus causes metals to lose their electron becoming ions which then goes on to form oxides(also known as rusting). If anything Carbon dioxide is acidic because it forms carbonic acid by interacting with water.

Yeah, thats what I meant. Chemistry is not my forte.

 

[DrAce]

“We saw something really different,” Lyons said. “We saw very rapid isotopic variability, which suggests there wasn't much sulfate in the early ocean and that oxygen in the atmosphere remained comparatively low for more than 80 percent of Earth's history."

http://www.sciencedaily.com/releases/2004/10/041025115640.htm

Here is a neat paper that sugest that O2 levels haven't really increased or decreased that much once fauna appeared on the scene. http://www.sep.org.uk/catalyst/articles/catalyst_18_4_355.pdf
-see the graph on page 18

For the record, the period in question is literally a billion years before multicellular life reared it's ugly head on the earth.

i.e. yes, there was a long time where the earth had low oxygen. There was no-one around to enjoy it, though.

It makes it a kinda mute point as far as this discussion is concerned.

 

[Travis K]

For the record, the period in question is literally a billion years before multicellular life reared it's ugly head on the earth.

i.e. yes, there was a long time where the earth had low oxygen. There was no-one around to enjoy it, though.

It makes it a kinda mute point as far as this discussion is concerned.

I disagree. From what I can tell O2 levels haven't fluctuated that much, there is some evidence that at one time O2 levels hit 35% But we really don't know for sure. Also if they did hit the 35% level was it at a time giant arthropoda roamed the earth? I haven't really seen any thing suggesting Ts bigger than what we have today ever existed. Have you? The creature discussed earlier was a giant water scorpion so that doesn't count. I know there used to be 12" roaches, but again were those around during the brief time the earth "may" have had 35% O2 levels?

It is safe to say that our planet's O2 levels have been Very stable since plant and animal started sharing it. Most... er, many people know/feel that the major size inhibiting factor to inverts is there exoskeleton and not their breathing apparatuses.

In regards to O2 levels this fiction movie suggest it is the "lungs" that inhibit large size, but if that were the case I think we would have very large inverts with more efficient lungs, but we don't. Exoskeletons just are not a good design for larger land dwelling creatures.
[YOUTUBE]wGGD9FUlngQ[/YOUTUBE]
And lets face it... Would we really want giant inverts roaming the earth?

 

[DrAce]

I disagree. From what I can tell O2 levels haven't fluctuated that much, there is some evidence that at one time O2 levels hit 35% But we really don't know for sure. Also if they did hit the 35% level was it at a time giant arthropoda roamed the earth. I have really seen any thing suggesting Ts bigger than what we have today ever existed. Have you? The creature discussed earlier was a giant water scorpion so that doesn't count. I know there used to be 12" roaches, but again were those around during the brief time the earth "may" have had 35% O2 levels?

It is safe to say that our planets O2 levels have been Very stable since plant and animal started sharing it. Most... er, many people know/feel that the major size inhibiting factor to inverts is there exoskeleton and not their breathing apparatuses.
...

The data regarding atmospheric oxygen levels are all inferred - that doesn't mean they are wrong. Interestingly enough, most of the data is pretty consistent - meaning that more than one technique has given us the same data. Even where there are discrepancies, the over all pattern has stayed about the same.

That is, there wasn't oxygen in the atmosphere (well, there was, but not much of it) until somewhere around 2.5 billion years ago, when plants stuck it there. It increased to a steady state of around 5% - while iron in rocks absorbed it (leading to a rusty layer in some parts of the world), until it then rose again around 600 million years ago - about the time when multicellular organisms came around.
It's since gone up and down, peaking, as you say, at ~35%, and now hovering around the 20% mark.

My comment was in reference to the quote you pulled suggesting that there wasn't much oxygen around in the old atmosphere. They were talking about a LONG time ago - before multicelled organisms were about. Hence my commenting that it really wasn't relevant here.

 

[kalvaer]

Maybe there was more Oxygen a few million years ago, but personally I'm glad the levels dropped. If it hadn't, we more than likely would of made it to the top of the food chain.

While we all need it to survive, to much of it is not a good thing. Especially at elevated pressures, which if there was so much more oxygen as everyone says, then one could conclude that the atmospheric pressure would also increase. At those levels.. It will kill us humans. Think of a scuba diver, and what they call Hyperoxia (Oxygen Toxicity Syndrome)

 

[Radamanthys]

Maybe there was more Oxygen a few million years ago, but personally I'm glad the levels dropped. If it hadn't, we more than likely would of made it to the top of the food chain.

While we all need it to survive, to much of it is not a good thing. Especially at elevated pressures, which if there was so much more oxygen as everyone says, then one could conclude that the atmospheric pressure would also increase. At those levels.. It will kill us humans. Think of a scuba diver, and what they call Hyperoxia (Oxygen Toxicity Syndrome)

Not, it won't kill us. Oxygen may have a different atomic mass from other elements, but it wouldn't crunch us into little balls with the increase. We are talking in per cent here. If i take 20% of 50 gallons and 50% of 50 gallons, i'm not increasing the volume of gas.

 

[kalvaer]

By volume, then sure. Currently its about what,78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide. But would it not be safe to assume (and I hate assuming things but for the interests sake and learning , I am going to) that with a massive increase of O2, you will also have an increase of pressure, Its not like the other gases are all going to disappear (Not really sure what the content and pressure was a few million years ago.. I'll have to go look it up)

At 2 bar (double the current atmospheric pressure. 100% O2 will kill us humans. At 10 bar normal air will kill you as well (compressed air from the standard atmosphere at least)

Of course we might of evolved differently ourselves with a difference in both volume and pressure of O2. Not everything needs Oxygen, Some of the creatures and plants found at 7 mile ocean depths are proof of just that. Maybe we wouldn't either if things had turned out different

 

[skips]

By volume, then sure. Currently its about what,78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide. But would it not be safe to assume (and I hate assuming things but for the interests sake and learning , I am going to) that with a massive increase of O2, you will also have an increase of pressure, Its not like the other gases are all going to disappear (Not really sure what the content and pressure was a few million years ago.. I'll have to go look it up)

At 2 bar (double the current atmospheric pressure. 100% O2 will kill us humans. At 10 bar normal air will kill you as well (compressed air from the standard atmosphere at least)

Of course we might of evolved differently ourselves with a difference in both volume and pressure of O2. Not everything needs Oxygen, Some of the creatures and plants found at 7 mile ocean depths are proof of just that. Maybe we wouldn't either if things had turned out different

Chemistry is my forte. No, you wouldn't have an increase in overall pressure, but you would obviously have an increase in the pressure due to oxygen (partial pressure). According to henrys law (gen chem I) an increase in partial pressure is proportional to an increase in the gas's solubility, say in blood. This would completely saturate hemoglobin whose saturation is tightly controlled by conditions in different parts of the body. That's not the point of this post though. I'm going to try and look up some articles on giant spiders.

 

[skips]

"...Recent geophysical data as well as theoretical models suggest that, to the contrary, both oxygen and carbon dioxide concentrations have changed dramatically during defining periods of metazoan evolution. Hyperoxia in the late Paleozoic atmosphere may have physiologically enhanced the initial evolution of tetrapod locomotor energetics; a concurrently hyperdense atmosphere would have augmented aerodynamic force production in early flying insects. Multiple historical origins of vertebrate flight also correlate temporally with geological periods of increased oxygen concentration and atmospheric density. Arthropod as well as amphibian gigantism appear to have been facilitated by a hyperoxic Carboniferous atmosphere and were subsequently eliminated by a late Permian transition to hypoxia. For extant organisms, the transient, chronic and ontogenetic effects of exposure to hyperoxic gas mixtures are poorly understood relative to contemporary understanding of the physiology of oxygen deprivation..."

T. Owerkowicz, R. M. Elsey, and J. W. Hicks
Atmospheric oxygen level affects growth trajectory, cardiopulmonary allometry and metabolic rate in the American alligator (Alligator mississippiensis)
J. Exp. Biol., May 1, 2009; 212(9): 1237 - 1247.


this is all i found in 10 minutes. I think the theory holds some water.

 

[DrAce]

Chemistry is my forte. No, you wouldn't have an increase in overall pressure, but you would obviously have an increase in the pressure due to oxygen (partial pressure). According to henrys law (gen chem I) an increase in partial pressure is proportional to an increase in the gas's solubility, say in blood. This would completely saturate hemoglobin whose saturation is tightly controlled by conditions in different parts of the body. That's not the point of this post though. I'm going to try and look up some articles on giant spiders.

With all due respect, much of this is wrong.

Unless another gas is being removed, you would certainly get an increase in total pressure. Dalton's Law basically says that all the partial pressures add up to the total pressure (and gives us the definition of a partial pressure). If the partial pressure of oxygen has increased, and no other one has decreased, then the total pressure MUST go up.

That being said, the earth is quite a complicated system. Gasses, as you correctly state, will dissolve, using Henry's Law (which isn't so much a law as it is a statement of what a solubility equilibrium looks like).

Oxygen is a terrible solute in water - (~6 mg/L at body temperature). That's why haemoglobin is used to transport it. For the record, the saturation of haemoglobin isn't so much determined by the body, but it is removed by tissues which are demanding oxygen.

 

[Drachenjager]

its not a bloody spider its a bloody crab!!!!!!!!!!!!!!

http://en.wikipedia.org/wiki/Megarachne

there you go, this is no peer reviewed study, but megarachne is an ancient genus about wich you should find some info on many different websites. 3' legspan, a huge carboniferous era aranea. In order for a blondi to be arguably the biggest spider ever, it would have to be at least 3 times the size of the biggest ever discovered...

I don't know about you guys, but at 6'4", I wouldn't feel safe about a 3' spider in my environment... I have seen many of my spiders attack preys twice their size... A defensive bite from a 6" spider is one thing, but a (3')spider hanging on and injecting all its venom in the intention to digest your tissues as it pulls you with 8 legged torque to its burrow kind of freaks me out