Which critter is eating all the fauna?

I was sad to see today that all my fan worms and some small sponges in our new tank are history, I've learned the hard way that I like them better than clawed crustaceans. I have three scarlet hermits, one dwarf blue leg hermit and three peppermint shrimp. There is a Xanthidae crab [edit: eriphia sebana] that has been there since the beginning so I'm not inclined to believe it was him unless he got hungry enough. The blue leg and one scarlet have been there for a week with no issues, the peppermint shrimp and other two scarlets were added yesterday so I'm thinking one of them is the culprit. Has anyone had any experience with any of these eating fan worms or sponges?

 

what kind of fish do you have? Wild caught peppermint shrimp might be use to eating them, they typically dont, but ya never know with wild caught anything. They eat what they can, when they can in the wild.

 

No fish yet, maybe a goby in the future but that's it. I found out the crab I had was actually a eriphia sebana aka red eyed reef crab, and supposedly bad news... go figure with the claws. Anyway, he is out now, the three huge peppermints were pushed on my g/f by the lfs as a 2 for 3 deal, way too big for an 8 gallon so they're going back also. I hope the hermits didn't have anything to do with it because we like those guys. We have no intentions of adding anymore carnivores to this tank, it's too small for any life cycle to sustain before it gets mowed down by a hungry predator.

 

they are omnivores, not carnivores. They are scavengers, they eat anything. There is no 100% reef safe crab, period. The jermits are the closest thing to it though, but again, if they see a dead fish laying on the bottom, they will eat it.

 

What are the chances that the colonies just crashed? Many of those small feather dusters and sponges are colonial. They can suddenly appear when there is plenty of food and then just as suddenly disappear when they can no longer be sustained.

 

Xanthidae family of crabs eat feather dusters and corals and sponges etc... Which explains why they poisonous if eaten. Numerous fatalities related to people ingesting them. So I would say that lil red eye monster is the culprit.

 

I thought of this possibility too, but one of the tubes has a large hole busted into it's lower section like the worm was pulled out by it's tail.

I have a feeling it was the crab, we'll see if more life springs forth without him. The shrimp seem to be concentrating on the sand more than anything, but I think they are just too big and to have three of them in there side by side seems like overkill in this small tank.