Snail graveyard; possible mantis

[Matt]

For a long time, we've heard clicking in our tank, and thought there may be a mantis in there somewhere. Today, when we were taking some LR out for a GHA scrub, we moved a largish rock and noticed a snail graveyard behind it. There were about 10 shells back there, and then I saw a slim, dark bullet-shaped scuttle. It moved about an inch, behind a shell, and then stopped. It was in a dark area of the tank, but I'm pretty sure it was a mantis, a bit more than 1" long (so pretty small).

There were three live snails back there (lined up for dinner?) and a bunch of dead ones. The shells weren't cracked, though. I thought that mantis' would break the shells...

We also collected three crabs in the reorganization. A "gorilla" - about 1" across, including legs. Another a bit bigger across than the gorilla, but with a much smaller body, but very long legs and pincers (not arrow-crab long, but long). Finally a very cute small purple crab. They all went into the sump - no harm there. The purple crab had the teeniest legs and pincers I've ever seen. It was almost all body, and about 1/3" across.

What fun! I guess I'll have to look into ways to trap a mantis now, since it has expensive tastes (assuming that's what it was...).

[G1GY]

I have a bullseye pistol shrimp that does the same thing. I'm not so sure that a mantis will keep it so organized back there, but I know for a fact that a pistol will keep a nice neat pile. Also, My pistol just walks right up to the snail and just carries it back to it's home for dinner and then eats it without damaging the shells. I've also watched it kill hitchhiker crabs after I've injured them.

Hope this helps. :)

[BCOrchidGuy]

I'd agree with the last post. I've always had problems though with hermit crabs eating my snails so I don't mix them now. I did have one little blue legged hermit that liked to eat the SPS polyps so he didn't last long in the tank. When the hermit crabs ate the snails though it was never a nice neat pile it was always so the hermit could have the shell.

Doug.

[untamed]

Lucky you! I would recommend that you make weekly runs to the LFS to stock up on snails. (cheap food!) No one is interested in snails, but I guarantee you will have many people interested in watching your pet devour them!

[Matt]

I'd like to see the critter in the light so I'd have a better chance of identifying it. I looked over some of the shells again, and none of them are smashed. Something is killing them in that particular area, though, unless there's a huge coincidence that I've just found where snails go to die.

Sadly, though, given that whatever it is has been in the tank since I bought that LR (over a year ago), and this is the first time I've got even a shadowy glimpse of it, I don't like my chances of entertaining friends with the escargot-feeding.

I don't have any hermits, or any other non-hitch-hiking crabs in that tank. I wonder if one of the hitch-hiking crabs (perhaps the big spidery-legged one) could be the murderer? I caught all three crabs right in that area. I blamed the shadowy shrimp-like creature - but might it be an innocent?

[danny zubot]

I did have one little blue legged hermit that liked to eat the SPS polyps so he didn't last long in the tank.

Is it what they sometimes call an electric blue hermit? I have a couple that hang out on my Prostrata Acro at night, but I'm not sure why.

[BCOrchidGuy]

It was your typical (or not so) blue legged hermit, you could see it completely strip a patch bare leaving nothing but skeleton.

Doug

[mark]

Ah, the amazing properties of LR. A year later and you're still discovering stuff for the first time.

[G1GY]

Ah, the amazing properties of LR. A year later and you're still discovering stuff for the first time.

Very true. This is what I love about reef aruariums. :)

[justinl]

shells don't necessarily have to be broken by a mantis. If it can, a mantis will just pull the snail/hermit out of the shell without smashing anything. It just means less effort for the mantis. I wouldn't rule a mantis out, but wouldn't jump to conclusions either until you've gotten a good look at it.