Advertisement I just recently noticed on one of my spiders that she, to my surprise, has more than one pair of spinnerets! I had no idea that any species had more than one pair. (Yes, it's ok to laugh at my ignorance ) I find this to be very interesting, so I try to read more, what they are for and how many pairs of spinnerets can a spider have. I was able to find some reasonable detail information (e.g. Liphistius has four pairs of spinnerets!) and some of the different use for different pairs. My questions, that I could not find the answer for is: do all Theraphosidae have two pairs of spinnerets? As I understand from what I read, one pair with the male is for making the spermweb, but what do the female use, if functional at all, the second pair to? Is having two pairs of spinnerets a defining characteristic with Theraphosidae?