I think there's an error on page 26. The text on it Zechs is asking Shion to get next to him, but it's clear he's asking Caron since she goes next to him the next panel.
Just came back to see how far Nano has come after her serious arc.
In the beginning she probably wouldn't even have thought this day would be worth remembering and be completely insignificant, and it's easy to see why Future Nano ended up the way she is evident from how our Nano used to be...
Maybe it laid eggs and there are also tiny (in comparison) baby spiders that trap and eat the smaller prey until they grow huge like their mother and start to hunt bigger game, or there could be other spider species in that cave.
I'm definitely not a spider expert or anything though, but...