Scarlet hermit crab eater... ideas?

[Mihai]

Hi,

Last night I was taking some pictures (weird creatures come up at night) and I saw both my scarlet hermit crabs. Today when I came from work I discovered the remains of one of those two scarlets. Only the feet and the claws are left. They are even aranged in the same positions where they used to be when it was alive. No sign of the shell.

The tank has no known predators: some herbivour snails (Turbos, Nerite, Cerith), 3 x Nassarius snails, 10 x bumblebee snails and a few more hermit crabs (baha and black&white). All the population was stable for the last month or so (lost one baha hermit 2 weeks ago).

During the night the hermit was doing well (eating and looking happy), so I assume that it didn't just die of old age, but was eaten. And since I don't have any predators on hermit crabs I assume it's a hitchhicker. The thing is that during the same night I heard some noises that I attributed to the pump (perhaps was not the pump). It was like somebody would have taken a snail shell (small one) and knock it to tank glass fast and many times per second (5-10). Do any of the bad guys (mantis/pistol shrimp) do so many noises per second? I doubt I have one of the bad guys as only 2 hermits are missing in one month (not very hungry if I have one).

Should I look for one of the bad guys? Anything else could get my hermit?
How can I check for the bad guys?

Thanks,
Mihai

 

[tazdevil]

Sounds like you have a mantis. Prepare for war.


Btw, pistol shrimps aren't necessarily "bad", just more of a nuisance with their noises.

 

[Juck]

Sure it's not just a moult?

If the shell is not sitting there empty then it could be that he's moulted and skulked off somewhere while his carapice hardens.

 

[cdeakle]

Sure it's not just a molt?

I agree, Could just be a molt. Either that or starvation. I had some blue legged hermits and a zebra hermit die due to lack of food.

Double check on the noises though because if its not mechanical then thats a good sign of a mantis/pistol....

 

[Anonymous]

As others have stated it could be a molt though I would venture to say
if you heard repetitive tapping, congratulations you have a critter of the order Stomatopod ( Mantis Shrimp ) probably of either the superfamily Odontodactylus or Gonodactyloidea commonly called smashers These marvelous creatures have a club-like appendage that is used to break apart snails, crabs, etc. and consume them. These critters can also be heard breaking off pieces of rock creating a lair for themselves. Probably the reason you haven't had any problems before is that Mantis shrimp while being predators are also scavengers and if supplied with enough to eat will not go out of their way to kill. If you added anything recently such as a coral it is possible it came in that way.
I know people have horror stories about these creatures, they are normally of the Spearer type Mantis which will kill fish.
These creatures are relatively secretive ( though I've had some that would come out and great me ) but by chance if you can get a glimpse or a pic I can do an ID on it.
My suggestion is to either trap and remove it ( many people would love to have it ) or to target feed it and learn to appreciate their beauty.

Regards,
David Mohr

 

[Mihai]

I did setup a trap last night and nobody showed up (by morning nobody sampled the fresh shrimp either). I start to believe that it was just a molt (honestly being beginner and all I never thought about the posibility of a molt). That would also explain why the shell is not anywhere around (I looked for it quite carefuly, expecting to find it smashed). Also the noises didn't return this night, it might have been just the pump. I'll update if anything else develops.

Thanks,
M.