The most common problems I see with people and rigid bodies are 1) unapplied scale on objects (dunno why, but Blender will freak out with scaled objects) and 2) normals pointing the wrong way (this is how blender knows the difference between a rock and a cave) and 3) not understanding collision types.
The first thing I’d suggest is, your scene looks absolutely littered with empties. You should be working out an understanding of rigid bodies in a fresh file. Whenever running into trouble, simplify the problem as much as possible.
A big warning to me here is that your tentacle has an armature. Rigid bodies do not use deformation! If deleting that armature changes how your tentacle looks, then your tentacle will be interacting in some other place. If you need something that approximates your tentacle, do so with non-rendering objects (cubes and spheres and such) that are bone parented to the armature.
It would be a lot easier for people to tell you what’s going wrong if there was a file. I realize you may not be able to upload here yet, but there are other hosting sites in the world. Personally, I’m out of town for a few days and won’t look at a file until I get back home, but given a file I’m sure somebody else would be able to help you sooner than that.