OK, good enough. Guess they are physiologically more like jumping spiders. Well, even they use anchor lines a little. I'm thinking arenea evolved to be intelligent, and with better offensive use of silk glands, sacrificing them for use as rigging. The fact that she used a strand of silk to float away in the first part of her lifecycle is explained by the fact that the hatchlings are a pre-pubescent form. Upon puberty, the silk glands in the abdomen stop functioning and the ones (presumably) in the throat start to develop as the energy and materials for silk production are repurposed. I know, this dosn't fit all too well with real spider biology, but hey, it's a magical world, and I'm sure the gaming gods would rather have throat silk glands than have a hybrid Merenita point her butt at the enemies and shoot silk out of it!