User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-4687489-20120303150429/@comment-5020152-20120727155131

Khezus use their four limbs to crawl on ceilings because it just wouldn't be possible for them to do it only on two limbs. Gigginox is flatter than the Khezu, and this might be because it needed to evolve to fit into smaller spaces for some reason.

If this is true, it would explain why Gigginox is a weaker flier than Khezu. After all, it doesn't have enough body space for strong flight muscles. So much of its underbelly/chest area is used to produce toxins, and its wings are also a lot flabbier than Khezu's.