User blog comment:Kogath/Monster Hunter X Discussion/@comment-25083735-20150710192336/@comment-5167887-20150712193324

I see Bubbles as a leviathan that has adapted to live on land, which is why she has special feet and passed from crawling to actually walking. But in the end i can clearly see her aquatic origins.

Ivory Lagiacrus, Agnaktor and Quartzeps are other Leviathans that adapted well to land-based life, but only in terms of behaviour. Remember how their tiny legs don't allow them to walk on land without their stomach touching the ground -this generates friction and therefore slows them down-. On the other hand Bubbles has adapted morphologically, which is why she can be so swift on land. However, she doesn't live far from water and might have to moisture her skin or drink regularly -this shows that she came from an aquatic environment-.

This make me think that Bubbles is more evolved than other species Leviathans.