I've just looked at some chapters of it, and it looks quite good. It presents some forms of possible evolutions. However, there are some things that aren't realistic. For example, the insects that dig a tunnel to get to the underground air pocket, would instantly flood the air pocket. It is like making a hole into a globe, the air would escape, and the water would fill the pocket.
Ok, back On Topic, if there is such thing in this thread. A blob that is sticky and imprisions animals on touch, could then feed onto them. Probably killing them bu starvation (as the animal cannot get away, they cant get food nor water, and eventually die), a toxin that is applied on contact, or something like that. That could work like those sticky strips that are used to catch flies, but feeding on them. Probably, being able to get even small animals, like rabit or small bird sized. Such a blob could work. Probably not in the niche structure, but its realistic. Anything much more advanced is not realistic.