User blog comment:Jamintheinfinite/Subnautica Creature Evolution/@comment-28450065-20180331231031/@comment-28450065-20180401165950

The point is that it shouldn't split off at that point. The Cave Crawler, Blood Crawler and Crabsquid should all split off from a hypothesised common ancestor.

I don't think that the Blood Crawler is a descendent of the Cave Crawler either.

Say you have one common ancestor, that splits off into the Crabsquid line, the Shuttlebug line and then a third offshoot which later diverges into the Cave Crawler and Blood Crawler.