Why do new world tarantulas have irritating hairs but old worlds don't?
- Thread starter Sparkn
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Evolution?
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Maybe old worlds just developed better bites and faster speeds and just don't need it? :?
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as tarantulas evolved on different continents, i suppose new world ones had more of a need for projectiles to cope with their surroundings.
Complete shot in the dark.
Could it be that because the ambient temperatures in the old world areas are quite high (I'm sure there are exceptions) meaning that the tarantulas are more 'alert', have a higher metabolism, which means they can strike faster, move quicker, since they do not need to warm up their muscles.
In the new world, the average temperatures are lower. So instead of being lightening quick, tarantulas have developed to "taste bad" or have negative effects on the consumer which would ingest them.
:?
Could it be that because the ambient temperatures in the old world areas are quite high (I'm sure there are exceptions) meaning that the tarantulas are more 'alert', have a higher metabolism, which means they can strike faster, move quicker, since they do not need to warm up their muscles.
In the new world, the average temperatures are lower. So instead of being lightening quick, tarantulas have developed to "taste bad" or have negative effects on the consumer which would ingest them.
:?
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All I know is, I'd hate to be the predator with a mouth full of T.blodi urticating hairs!
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I agree.Why ask why nature is what it is beautiful and diverse.
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No one really knows so everything here will be speculation but I believe it's an evolutionary thing.
Old world Ts tend to be faster and have more powerful venom so they didn't actually need another defense mechanism. Their speed alone is usually more than enough to escape or gain the upper hand for a counter-attack.
NW Ts, being slower with milder venom required another weapon that would give them the upper hand when needed. Flicking a cloud of these barbs in the air serves to incapacitate a predator to allow the T more time to escape or blinds the attacker to allow for a counter-attack.
In conversation with another keeper here in Canada, we discussed where these tarantula types may have split and we came up with the Ephebopus genus as the most probable candidate. Obviously, this is only theory but the the fact that Ephebopus specimens have a smaller amount of urticating barbs in an odd location (they have them on their chelicerae rather than their abdomens) coupled with the odd shaped front feet (shovel shaped - similar to Poecilotheria) make this a logical choice.
Old world Ts tend to be faster and have more powerful venom so they didn't actually need another defense mechanism. Their speed alone is usually more than enough to escape or gain the upper hand for a counter-attack.
NW Ts, being slower with milder venom required another weapon that would give them the upper hand when needed. Flicking a cloud of these barbs in the air serves to incapacitate a predator to allow the T more time to escape or blinds the attacker to allow for a counter-attack.
In conversation with another keeper here in Canada, we discussed where these tarantula types may have split and we came up with the Ephebopus genus as the most probable candidate. Obviously, this is only theory but the the fact that Ephebopus specimens have a smaller amount of urticating barbs in an odd location (they have them on their chelicerae rather than their abdomens) coupled with the odd shaped front feet (shovel shaped - similar to Poecilotheria) make this a logical choice.
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hmmm....all good theories...fr sure, heres mine.
couldit be a mixtureof environment and prey items combined? for instance. in africa the temps are hot in most locations very hot to be exact, which in turn Would make more of the tarantulas there burrowers and if most arent out and about the risk of attack from a predator is less. the stronger venom may also be contributed to prey items being far and few along with the evolutionary factor there second defence(u hairs) have be done away with.
now for new world Ts could it be since more are either arboreal, or just more out and about they either kept or gained U hairs. also being out and about more means more chance for an attack on them. not to mention the jungles of south america have alot of bug eating animals. not also prey may be responcible for there lack of potent venom mainly because its more abundant and again being there other defence is there. (u hairs)
these are all just speculations. maybe one of us is close or we may all be far off. maybe u hairs and the lack of have nothing to do with venom strength at all. maybe bother evolved for totally diffrent reasons....who knows. but i will say lets face it...seems as though anything not in the americas seems to be more "deadly or potent" or futher more...either more evolved or less...thats something we may never know..which is a weak point all of evolutionary theory.
couldit be a mixtureof environment and prey items combined? for instance. in africa the temps are hot in most locations very hot to be exact, which in turn Would make more of the tarantulas there burrowers and if most arent out and about the risk of attack from a predator is less. the stronger venom may also be contributed to prey items being far and few along with the evolutionary factor there second defence(u hairs) have be done away with.
now for new world Ts could it be since more are either arboreal, or just more out and about they either kept or gained U hairs. also being out and about more means more chance for an attack on them. not to mention the jungles of south america have alot of bug eating animals. not also prey may be responcible for there lack of potent venom mainly because its more abundant and again being there other defence is there. (u hairs)
these are all just speculations. maybe one of us is close or we may all be far off. maybe u hairs and the lack of have nothing to do with venom strength at all. maybe bother evolved for totally diffrent reasons....who knows. but i will say lets face it...seems as though anything not in the americas seems to be more "deadly or potent" or futher more...either more evolved or less...thats something we may never know..which is a weak point all of evolutionary theory.
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I'm guessing that urty hairs got their start as something other than a defensive weapon. Perhaps they began as something they used to line the burrow and/or eggsacs only. The barbs were more effective so over generations they evolved to have nastier barbs on their hairs (bristles really) then at some point they started kicking clouds of them off for more of a defensive capability and continued to evolve them in that direction.
As with the rest of you, just a guess.
As with the rest of you, just a guess.
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I'd be interested to know if there is an energetic difference to producing more potent venom vs. urticating hairs. Perhaps the compounds or concentrations of compounds in potent venom (vs. less potent NW venom) is more energetically demanding. If so, there might be more evolutionary pressure to come up with alternate defense mechanisms. I'm assuming urticating hairs are a more derived adaptation. If I'm not mistaken (and I might very well be), urticating hairs are just a structural modification to be sharp and barbed, aren't they?
One other thing, urticating hairs are a long range weapon that they can use while retreating. Fangs and venom put the T right into harms way, most often the mouth or paws of the attacker
One other thing, urticating hairs are a long range weapon that they can use while retreating. Fangs and venom put the T right into harms way, most often the mouth or paws of the attacker
That would be a neat discussion. I would nominate Holothele spp. as a probable candidate for their complete lack of urts and their similarities to OBTs. Holothele spp. stick out like the sore thumb for New Worlders IMO.
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Don't psalmos lack the hairs altogether? And they seem very similar to pokies...
Though India and S. America were never close together, so I don't know that really applies. Never mind
Yep. So do Tapinauchenius spp.
They look kind of similar to some African arboreals too, IMO.
A couple other genera lack urticating hairs. Zoltan would know.
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All members of the polyphyletic group referred to as the NW Ischnocolinae (Catumiri, Guyruita, Hemiercus, Holothele, Oligoxystre, Sickius) lack urticating setae, as do the 2 closely related NW genera already mentioned (Psalmopoeus, Tapinauchenius). You can't forget to include Ephebopus, which possess urticating setae on the pedipalps, not the abdomen, in this discussion.A couple other genera lack urticating hairs. Zoltan would know.
Eric
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Perhaps all Ts began as a spider with no urticating hair and weak venom, and when the continents split, they developed different stratigies for defense. Ts in the new world evolved to use thier hair as a weapon, while old world Ts simply made the venom they already possesed stronger.
Thats my theory and I'm sticking to it.
Thats my theory and I'm sticking to it.
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spiders evolved from tarantulas no?
I meant tarantula, sorry. :8o
It's evolutionary, of course. But the question is, "why?". Why was this specific trait either abandoned by old world, or evolved into by new world?
Firstly, it's important to understand the major differences (that I know of) about OW and NW T's.
1. Venom
2. Speed
3. Hairs
4. Comfort 'zone' (Humidity, temp, etc)
A pre-existing trait which has no affect (positive or negative) on the ability to reproduce or survive will not be bred out.
It would help to figure out which came first.. NW or OW T's? Which are more like the original predecessors? Of course, without a lot of genetic testing this is mostly just speculation, but here's one idea, as an example:
NW T's actually came first, and originally, T's were more rugged, and slow(er), had hairs, were less venomous, and were comfortable in drier enviroments. . .
Then, maybe these predecessors somehow arrived in the rain forest and were faced with larger and fiercer predators, and prey. Only the fastest T's with the strongest venom were able to consistantly down prey and escape attacks from predators, and thus survive to mate. Maybe urticating hairs were a liability in this super moist enviroment?
It's a possibility, but for some reason I doubt that T's would actually evolve to become slower and less venomous than the original predecessors. I think they'd have to be put in an enviroment which would require the slower, less venomous, and more hairy species of tarantula to die off and thus only the strong/fast/most agile to survive.
Firstly, it's important to understand the major differences (that I know of) about OW and NW T's.
1. Venom
2. Speed
3. Hairs
4. Comfort 'zone' (Humidity, temp, etc)
A pre-existing trait which has no affect (positive or negative) on the ability to reproduce or survive will not be bred out.
It would help to figure out which came first.. NW or OW T's? Which are more like the original predecessors? Of course, without a lot of genetic testing this is mostly just speculation, but here's one idea, as an example:
NW T's actually came first, and originally, T's were more rugged, and slow(er), had hairs, were less venomous, and were comfortable in drier enviroments. . .
Then, maybe these predecessors somehow arrived in the rain forest and were faced with larger and fiercer predators, and prey. Only the fastest T's with the strongest venom were able to consistantly down prey and escape attacks from predators, and thus survive to mate. Maybe urticating hairs were a liability in this super moist enviroment?
It's a possibility, but for some reason I doubt that T's would actually evolve to become slower and less venomous than the original predecessors. I think they'd have to be put in an enviroment which would require the slower, less venomous, and more hairy species of tarantula to die off and thus only the strong/fast/most agile to survive.