Disappearing inhabitants....Help!

In the last three months since I started my tank I've had 3 shrimp, 3 crabs and now a lawnmower blennie go missing . I can deal with the inverts possibly dieing and being eaten by the CUC (I actually saw one of them carried off after his death). However, I am having a hard time dealing with my blennie being in the tank one night and the next afternoon being gone. Could the hermits devour him that quickly, he was 4" long? Do I possibly have a mantis shrimp, I've seen no sign of one? I know I have a huge bristle worm but could that be killing things? I'm growing weary of putting stuff in the tank only to have them come up missing. I have two clowns that are doing fine. My water levels are testing all good. What is going on with the rest of the creatures?

BTW: I've searched all over the floor and he isn't there.

 

A mantis wouldn't eat your fish unless it was a spearing type, which are not common hitchhikers in live rock. Have you heard any clicking or popping sounds in the tank? Do you have a ground probe in the tank? Are your temperature and salinity staying level and not experiencing any large swings?

 

Good news....kinda. I located the Blennie in the HOB. I'm not sure if he will make it after spending the last 4 days in there, he looks very pale but he seems to be happy to be back in the tank and is already nibbling the glass. I'm not sure how he got in there since I have some egg crate over it but he did and managed to get sucked through the U-tube.

 

OK, one problem solved, now how about them inverts?

 

Don't know about them yet, I do need to get the ground probe in there and possibly remove a giant bristleworm or two!

 

I have never seen bristleworms eat anything but dead/dying animals but I have read that when they get very large, they can be a nuisance. How big is the one in your tank?

 

My Coral Banded Shrimp killed my neon blue hermit crab and probably was an accomplace in other deaths, but I see you don't have one. Some of my green legged hermits have tried to kill the other hermits (unsuccessfully). Perhaps it's one of your hermits, or a gang that goes after the crabs when they molt.