What makes a true spider a true spider?

[johnharper]

Just wondering what makes a spider a true spider?

John

[crpy]

basically the most obvious difference is.

True spiders have one set of book lungs and a trachea.

True spider chelicera are positioned more sideways or left to right.

"T"s chelicera are positioned more up and down .

Hence True spiders =Labidognatha

"T"s= Orthognatha

[Raikiri]

Hi,

well I think Labidognatha spiders are in a more advenced state than Orthognatha spiders. An orthognatha can't use orb webs and many good things since their chelicerae is not as good as labidognatha's. Because of this, they need more power to catch the same size prey. This difference makes a spider true spider. Just compare a Teraphosidae with a Ctenidae..