Mantis shrimp hunt... losing morale....

[Antegon]

My mantis prefers to make his home inside the live rock. He carves out little trails straight through the rock itself. My pistol shrimp, on the other hand, prefers to dig underneath the rock, making caves through the substrate and decorating/supported with shells (sometimes with live inhabitants) and small bits of rock underneath the rock structure. Try to figure out where the majority of the disturbance is coming from, underneath the rock or inside.

Also, a side note, it may not be an invert that is eating your CUC. I had a CUC massacre early in my reefing career. I blamed it on our Tiger pistol shrimp at the time. A year later the Tiger shrimp died, so I thought I could add some expensive hermits “Electric Blue Leg- $15/ea). They all disappeared within four days except for one. Turns out, my Pink Diamond Goby would attack any hermit or snail that wondered near its cave enterance. He would grab them by the legs and whip them out of their shells.

My mantis is out only during the day. He has a hole at the front of the tank and every night around tank

bedtime he goes into his hole a blocks the exit with debris, sand, and bits of shell. By daylight his hole is uncovered and has the diameter of a pencil. I don’t know if all mantis shrimp are mostly diurnal, or I’ve just trained mine.

That sounds like such a cool animal!!
Ok I tried to get pics of the area where the grey sand is seemingly been dug out/thrown from this circular hole in the rock, near where the first pile in the pic I posted is in the tank. Tough to see, best I could do -

Dunno if that is any more of a clue? It’s a pretty small hole, maybe half a centimeter if that in diameter. Hard to say tho, porous rock.

 

[xPhilx]

I learn something new everyday from reading everyones posts. Crazy! LOL

 

[cobast]

Everyone has different experiences so consider all possibilities. At one tage I was losing fish and cut and while I can't say definitively it was mantis shrimp, but it seemed more than a coincidence that over several months I found 3 small ones in my tank. 1 got stuck in my wier, one was at the back of the tank in the rocks which I caught using bait and a large pair of tweezers, and the 3rd I had to take out suspect rocks and dip in fresh water. In each case they were 2" or less and I never saw them in the light. There was always that clicking as described.
I have also seen clips online of mantis shrimp stunning or killing fish with their 'punch' which is as fast as a 22 bullet. They don't even have to connect. The pressure wave from the punch is enough to stun the fish.
As mine were ugly shrimp the lfs didn't want them...
Good luck catching the buggers

 

[PhreeByrd]

I have seen little 'sand piles' that look like that in my coral hospital tank... that's a small bare-bottom tank so the piles are very easy to spot. In that tank the piles are actually detritus from bristle worms. I know this for certain because there are no other creatures in that tank. You might keep an eye on the nearby holes in the rock just after lights out. Something will almost certainly exit those holes looking for food. Some small bait like mysis placed near the holes will probably also lure the critters out (after dark).

I suppose it's possible, but I would be very surprised if those holes have anything to do with a mantis shrimp. Mantis shrimp generally live in sand burrows and are relatively easy to catch. They are always hungry, it seems, and in my experience they are quite easy to lure to a trap. And, if you've had a mantis shrimp for any length of time, you will most definitely find broken snail shells in the tank.

 

[SFKINNC]

I keep a mantis shrimp in my display (maroon Odontodactylus havanensis). He’s small, only two inches, and a model citizen. I feed him regularly to ensure he doesn’t turn to the dark side. My CUC is all intact, so it’s possible to keep one of these in your tank with your other friends.
Your sand piles do look like excavation sites from a mantis. Chances are good that’s his rock. Try to identify your mantis before you nuke your rock, you maybe able to keep your super cool hitchhiker (or sell it).
That being said, do have extra shells for your hermits? They need new shells to grow into, otherwise they will attack snails and other hermits for their shells. If you don’t have extra shells, go to your local craft store a buy a bag of shells in the size and shape of the shells your hermit is currently sporting. (It’s usually much cheaper than your LFS.)

Skygirl997’s advice is very good advice. Hermit crabs definitely will kill snails for their shells. Go to craft store or Dollar Store for shells. (Definitely cheaper!) NOTE: you will need shells that are slightly larger than the ones the hermits are sporting now. The hermits need bigger shells as they grow, just as children need new shoes to grow into. This should help cut way down on snail fatalities, but an occasional loss should still be expected.

 

[vetteguy53081]

Clicking is no doubt- mantis. I caught mine in a trap baited with empty snail shell filled with krill.

I have a club member who got rid of his by introduction of a queen trigger. Undulated or similar trigger would also make it a meal ( that is, if you do not wish to keep it).

 

[Antegon]

Update -
This morning one of the two suspect piles of sand has been clearly freshly worked on, and something drug an old shell that had been in the same place forever right on top of it. If that helps or throws the hunt off further, I can’t say lol

 

[Antegon]

Also, several hermit shells that are dead aren’t crushed, but they each have a circular hole punched in them. Dunno if that’s related either? Sherlocking it!

 

[reef lover]

Strange!! Hope u figure it out!

 

[ThunderGoose]

Also, several hermit shells that are dead aren’t crushed, but they each have a circular hole punched in them. Dunno if that’s related either? Sherlocking it!

Circular hole in snail shells makes me think predatory snail. They have a modified radula called a drill.

What a fun mystery.

Well, maybe not for the dead CUC.

 

[Antegon]

Thanks. I dunno of any snails save one or two that aren’t killers and survive near the water line.

About to do a water change. Plan to smooth out the substrate and clear this construction site and see if whoever works there will come out to rebuild.

Update photo - the grey pile has now been built up onto the side of the relocated shell.

About to put a reward on this mystery.

 

[TheMantisman]

I see mantis everywhere;Facepalm...EVERYWHERE! ;Vamp... am I goin' crazy?

 

[OriginalUserName]

Wow. Ok good to know. Should I be on the lookout for one who seems violent and remove?

I've seen them go after each other when they want a new shell. Especially if the victim has molted. It is a sad sight seeing a shell-less hermit running around your tank. Hermits are cool but evil.

Edit. I also found a fairly large whelk hitchhiker in my tank once. I believe he came in fairly small and grew fat on my other snails. He was pretty cool looking. I wound up tossing him in with my peacock mantis but for some reason the mantis didn't want to eat him.

 

[lmm1967]

Throw a sacrificial live clam in the tank for a day or 2 - one you get from a seafood market, not one from your LFS - if you have a whelk - which is seems like you may have - it should find the clam, bore a hole through it's shell and eat it.

 

[00Barracuda00]

What was the mystery animal?!?!?! I must have closure!