Evildoers in my rock?

[steve9k]

I've had my 1st half of rock for 3 weeks, now, waiting for the 2nd. All's been quiet & peaceful (oodles of green & brown algae -- I'm hoping the cleanup crew is mighty hungry) -- until this morning. Looks like a battle was raging last night. I found the claw and leg of one of my porcelain crabs (no sign of the rest of him), and several featherdusters had been knocked off their rock (or maybe they fell), while another looks like its been chomped in two. I also had two little gray crabs with tiny pink pincers (rather ugly, but I kind of liked them -- what kind would they be?), but I think I'm down to 1, haven't seen the other in several days.

Would a mantis do this type of damage?

 

[docklink]

A mantis is possible as well as an as yet unseen crab. When you say some feather dusters fell off their rock, do you mean you are seeing the "duster" part on the sand? The worms are generally embedded in the rock but can lose their crown if stressed either through direct harassment or via water quality issues. They may grow new crowns in a few weeks time if the environment remains stable. How are your water parms? Crabs do shed their shells when out grown, though the shell is generally left as one piece in the process. HTH

PS My mantis(es) readily hammered on barnacles but never bothered featherdusters or xmas worms. I don't know if that's typical or not.

 

[dhebert24]

I recently found a 2" mantis shrimp in my TBS. I really don't want to go to the trouble to try and remove him since he's deep in the live rock. Has anyone had OK experiences with just keeping a mantis in the main tank? Would he bother fish? The snails, crabs, I'm not too worried about since they are easily and cheaply replaceable.

 

[Fountainhead]

I had a rock that was practically covered with feather dusters. One day I spotted a gorilla crab making a snack of one. Needless to say, the rock was completely clear of feather dusters within a couple of days.

I'd watch for gorilla crabs. If you've only had your rock for three weeks and haven't removed any yet, I'll bet you have a few.

 

[Iphis]

I've had a mantis shrimp from my tbs rock going strong in my tank since September of last year, along with a 2" diameter shell crab (not including his legs).

My snail/shrimp population was dessimated within weeks. A few tenacious hermit crabs still survive, and I have several porcelain crabs who seem to be completely ignored by these guys.

My emerald crabs were also all killed.

I do, however, keep both of them well fed. At least twice a week (most of the time three times a week) i will give both of them silversides and make sure they eat it.

This seems to keep them occupied for the most part. I can't keep all but the biggest turbo snails alive in the tank. I think I still have 2 cerinth snails left too, but any babies that they have are eaten fairly quickly.

Neither of them have touched my fish, or displayed intrest in my fish.