I'm going to make an @$$ of myself and actually try to discuss the physiology of the vasari. Bear with me here, guys
I think the reason they have those oh-so-overly jointed legs is because they were, at some point in time, flightless avians. That kind of zigzag leg structure probably meant that they relied on long-distance running over a flat, plains-dominated homeworld. As for the consumption, I'd probably bet that those layers of chitin on their faces conceal some kind of mouth.
Either that, or they photosynthesize. Who knows?