This occured to me when I was watching, but then I promptly forgot it.
The Rachna (Arachnae? I couldn't hear them properly...) were 'born hungry', and are spider-people. Isn't that The Silmarillion's Ungoliant, one of whose spider-babies would later almost eat Frodo? Is this a deliberate reference, or is there some actual myth that both were based upon? As far as I know, the Arachnae myth had nothing to do with hunger, and everything to do with vanity...
I leave that to the Tolkein-knowledgeable amongst you.