What would be killing gorilla crabs?

[MBVette]

So a few months back I bought some rock that was riddled with gorilla crabs. I have caught about a half dozen, but have seen a few more including a rather large one running around the bottom. I have a 30'' deep tank so I wait for them to show themselves towards the top of the rocks then get them, so a few have evaded me still.

But now in the last couple weeks I have found 3 good sized gorilla crabs dead on the sand bed, including the one which I thought to be the biggest one in the tank. What could be killing them? They are not getting eaten until the hermits find it, so Im at a loss.

In my tank I have:
Hermits and random snails
Naso Tang
Sailfin Tang
Chevron Tang
2 Chromis
2 osc clowns
watchman goby/tiger pistol (never seen on the side of the tank with the crabs)
diamond goby
Mystery Wrasse (have never seen it attack anything including cleaner shrimp)
2 Barlett Anthias
2 Flame Angels

The flame angels are very new and have not been around for the murder spree. Any ideas on this? I have had no other losses in the tank durring this time.

 

[chilwil84]

starvation

 

[MBVette]

if thats what it is Im fine with that, but if they were starving wouldnt they eat snails or something? My emeralds do fine, but obviously they have a different diet.

 

[KeMo]

Are you positive they are dead ? It's not a molt ?
If they are dead its prob a bigger crab killing the smaller ones.

 

[reefermad619]

You probably have a silver back in there somewhere.

 

[convict3]

You probably have a silver back in there somewhere.

thats awsome :spin3:

 

[jc-reef]

I had a smaller stone crab destroy a gorilla crab in front of my eyes....he cut all his legs off.:eek1:

 

[dublo8]

Mantis shrimp maybe?

 

[Peter T]

Are you positive they are dead ? It's not a molt ? ... ...

That's what I'm thinking it is. When you pulled the bodies out, did you check to see if the bodies were hollow or still had meat in them? Molts do look like the crab itself.

 

[AaronM]

Agree with molting. Another good way is to see if the eyes are hollow. After a molt they hide away for a few days because they're more vulnerable until their new shell completely hardens.

Are you finding them fairly intact? If something was eating them they'd probably be mangled.

 

[julie180]

I found if it smells bad, its dead, if there is little to no smell, its molt.

At least for my sally light foot crabs.

 

[ritter6788]

Mantis shrimp maybe?

Maybe if there are broken shell pieces laying around. A mantis wouldn't kill the crab and leave it there whole. I would guess molts also.

 

[MelbaToasty]

+1 on the stone crab as a possibility. I saw this happen in my tank also. Best of luck, I fought gorillas for a month. I thought it was so great that my live rock came with these free creatures. Then they killed my 3 striped cardinal fish.

By the way, I rigged a pair of needle nose pliers with some shrimp and snagged a few that way.

 

[MBVette]

I will have to go pull those things out next time, as I usually leave them and they disappear in a day or two. As I said with a deep tank reaching things on the bottom are a hassel, so I leave them if I dont think its an issue. Next time I see one I will be sure to grab it and take a look, I did not even think about it being molts.