# Tarantula vs truespiders



## WelshTan (Oct 23, 2009)

ok .. I *have* done searches on here and on google ... maybe I am doing it wrong but it only brings up conflicting "facts" to the question I am asking which is.....

Why are tarantulas and other spiders not classed as "true spiders"???

The only thing I could really find was to do with the axis rotation on the fangs.... T's go up and down only whereas "true spiders" rotate in all directions? 

I don't know if this is true as google has been known to be wrong on many of an occasion and I have found other sites which conflict this "information" 

So basically ... without sounding like a noob ... what are all the differences between tarantulas and "true spiders" for a tarantula not to be classed as a "true spider"?


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## ghordy (Oct 23, 2009)

Tarantulas are the spider that time forgot. In addition to the position of the fangs... they're larger than true spiders and I think there's something about their respiratory system that's different. True spiders have only one set of book lungs or none at all.

Reactions: Informative 1


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## Moltar (Oct 23, 2009)

Araneomorphs are "true spiders" with chelicerae that pivot up and down as well as pivot in-out. This includes orb weavers, jumpers, lycosids (wolf spiders) huntsmen, etc. Mygalomorphs are more ancient types of spider that have chelicerae which spread apart and pivot up and down but don't rotate in-out. Within this group are theraphosids (which we term tarantulas) and other primitive types of spider such as trapdoor spiders and funnel web spiders.

The chelicerae aren't the only defining characteristic. I believe there are specific differences in the feet and the spinerettes as well. There are some more scientifically inclined members here that could explain it more thoroughly but that's the general idea.

Reactions: Like 2 | Agree 1 | Informative 1


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## skippy (Oct 23, 2009)

the fang thing is the defining characteristic of a true spider i believe.
the difference between Ts and mygalomorphs is that tarantulas as we call them have the following 6 major characteristics:
1. They are very hairy
2. They have no less than eight eyes in a rectangular pattern.
3. Long finger like spinnerets.
4. Dense hair pads (scopula pads) with retractable claws. 
5. Small spiny objects called cuspules or cheliceral teeth on which prey can be crushed.
6. Two sets of book lungs
All Mygalomorphae may possess one or more of these characteristics but tarantulas possess all six.

beat me too it and with more info too!

you and me Moltar! outside!:}

Reactions: Informative 1


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## WelshTan (Oct 23, 2009)

Moltar said:


> Araneomorphs are "true spiders" with chelicerae that pivot up and down as well as pivot in-out. This includes orb weavers, jumpers, lycosids (wolf spiders) huntsmen, etc. Mygalomorphs are more ancient types of spider that have chelicerae which spread apart and pivot up and down but don't rotate in-out. Within this group are theraphosids (which we term tarantulas) and other primitive types of spider such as trapdoor spiders and funnel web spiders.
> 
> The chelicerae aren't the only defining characteristic. I believe there are specific differences in the feet and the spinerettes as well. There are some more scientifically inclined members here that could explain it more thoroughly but that's the general idea.


So with mygalomorphs ... does the "pivot in-out" mean in a sense they can retract their fangs? In the same sense as say .. a cat does its claws? Or am I totally off the mark?


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## Moltar (Oct 23, 2009)

WelshTan said:


> So with mygalomorphs ... does the "pivot in-out" mean in a sense they can retract their fangs? In the same sense as say .. a cat does its claws? Or am I totally off the mark?


No I described it poorly. I mean that as well as moving up and down they can rotate toward and away from the center axis of their body, not that they are retractable. And that's Araneomorphs that can do that, not Mygs.


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## WelshTan (Oct 23, 2009)

One of the reasons why I wanted the information into the differences between true spiders and tarantulas is because a lot of my friends (who I havn't managed to turn to like T's) say "eurgh how can you keep big bleeping spiders like that?" ... sometimes I reply " but they are not true spiders" ... and then look like an idiot as I do not possess the information to tell them why lol ... and the friends that I have converted to being fascinated in T's ask me why they are not "true spiders" out of general curiosity and again I lack the info ... not to mention I have genuinely wondered and searched myself previously particularly on the boards but it has brought up all the other true spiders and not the info I require lol ... thanks guys


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## jayefbe (Oct 23, 2009)

I personally don't like the whole "true spider" thing.  I mean, there is a clear distinction between Mygalomorphs and Areneomorphs, but calling one "true spiders" implies that the others are not.  Mygalomorphs are still spiders.  I've also seen "true spiders" in reference to the whole order Araneae in order to differentiate spiders from their relatives that still have clear segmentation within their abdomens.

Reactions: Agree 1


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## JimM (Oct 23, 2009)

Exactly, don't let the "true spiders" thing throw you, and frankly I wish they'd let go of this term. Tarantulas are spiders, period.

They're not scorpions, they're not mites, they're not ticks, they're not crabs, they're not isopods, they're spiders.

The "true spider" thing is akin to saying Viperidae are not "true snakes"...which would make about as much sense.

So don't tell your friends "they're not really true spiders" because you'd be wrong in the greater sense. I'd also avoid it unless you feel comfortable getting into an involved discussion about animal classification, and the confusing way we humans feel the need to put things into boxes, and how the characteristics that define those (often arbitrary) taxa are not consistent across genera.

Reactions: Agree 2


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## Bill S (Oct 23, 2009)

"True spiders" is one of those unfortunate terms, like "true bugs" that defines a particular group while giving the wrong impression that other closely related groups are somehow "false".  Tarantulas are spiders - real spiders.  Just as much as araneomorphs are.  But the araneomorphs are sort of the "figurehead" group of the order Araneae (spiders).  

As to the "fangs" (chelicerae) - in araneomorphs they work in opposition to each other, grasping toward the center.  In mygalomorphs they work parallel to each other, stabbing downward.  Picture ice tongs (or sugar tongs) vs the teeth of a saber tooth cat.


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## Tindalos (Oct 23, 2009)

if tarantulas are older and more ancient:? :? :? 
wouldn't be more accurate to call them true 
spiders?http://www.arachnoboards.com/ab/images/smilies/033102stupid_1_prv.gif


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## cacoseraph (Oct 30, 2009)

skippy said:


> the fang thing is the defining characteristic of a true spider i believe.
> the difference between Ts and mygalomorphs is that tarantulas as we call them have the following 6 major characteristics:
> 1. They are very hairy
> 2. They have no less than eight eyes in a rectangular pattern.
> ...



there is at least one eyeless species of tarantula (in mexico).  generally they do seem to have 8 eyes, though


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## Xian (Oct 30, 2009)

Bill S said:


> As to the "fangs" (chelicerae) - in araneomorphs they work in opposition to each other, grasping toward the center.  In mygalomorphs they work parallel to each other, stabbing downward.  Picture ice tongs (or sugar tongs) vs the teeth of a saber tooth cat.


That is a very good example to understand the difference between the two mechanics.


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## skippy (Oct 30, 2009)

that's true andrew:clap: i didn't think of that


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## Spxdxr (Apr 18, 2016)

ghordy said:


> Tarantulas are the spider that time forgot.


What do you mean by this? Got curious. Haha.

Reactions: Funny 1


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## cold blood (Apr 18, 2016)

Spxdxr said:


> What do you mean by this? Got curious. Haha.



He means they are "older, more primitive".

Reactions: Funny 3


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## Quixtar (Apr 19, 2016)

I'm not really a fan of naming anything as "primitive" or "modern/neo" and would rather have taxonomy focus strictly on morphological or genetic differences.


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## Hugo Oberholzer (Apr 11, 2018)

cacoseraph said:


> there is at least one eyeless species of tarantula (in mexico).  generally they do seem to have 8 eyes, though


I apologise for bringing this old thread back to life, I however want to know what tarantula you're speaking of here. I've done some searching with no results, and would like to know which tarantula species, or genus even, this is.


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