Ooh he got eaten...

Post by **wodesorel** » Wed Oct 20, 2010 3:07 am

I had one of the abandoned shelter crabs pass away. I know the crab had buried under to molt, but I'm not sure if it died of natural causes or if it was killed by the other crabs. (There two crabs unaccounted for, and one is just finishing molting - I checked. So I'm not completely sure which crab is the one that passed.)

What is confusing to me is that the three active crabs dug a giant pit to get to the body. I had been wondering what they were up to, and when I went to clean the tank tonight I knew what had happened as soon as I opened the lid. It was rather disturbing to see.

The crab had been dragged away from it's shell, and the main body was intact but missing all of it's limbs. I found a piece of the BP on the opposite end of the tank actually being munched on by another crab, and a tiny piece of the shield leg buried in another corner. (They were rotting, so they were not exo.) I searched the rest of the tank and sand carefully, but could not find anything else.

All six of these abandoned crabs have been fed some sort of shellfish/protein from day one with me - there was always either Krill, Shrimp, Plankton or Bloodworms in the tank. They were also getting fish and chicken occasionally. It was not a lack of protein that made them eat that crab!

I'm concerned because the crabs had been dumped with no information about them at all. The tank they were abandoned in was awful, and I'm not sure how long they were there. I am positive that there were other crabs that had passed away in that tank since I found multiple pieces of crab in the sand and in a shell.

Do you think they ate this crab as a learned behavior since it probably helped them survive previously? I'm going to need to combine tanks here in the next few months, and I'm spooked now about adding them to the other crabs if this is a danger. I haven't had intra-species cannibalism before, so I'm really at a loss

Any ideas?

DustAndEchoes · Post by **DustAndEchoes** » Wed Oct 20, 2010 11:33 am

It's possible he died of natural causes and the crabs cannibalized him after the fact, which may explain why they dug down to get to him (it's possible they could smell him through the substrate). It sounds like you're doing everything right as far as diet goes, but don't hesitate to keep a cautious eye out just in case.
It might be prudent to wait to add crabs too on the off chance this was preditorial behavior. I'm not sure how advanced their minds are, but if they were in poor conditions before, they might be in survival mode and not used to getting a steady diet of nutritious food, so they go after the weakened tankmates, but that's just a theory so don't quote me on it.

tigermoon89 · Post by **tigermoon89** » Wed Oct 20, 2010 4:59 pm

If it's imperative that you mix tanks, then I would suggest creating a barrier/divider in one of your larger tanks for these guys so that you can keep a closer eye on their behavior and know for sure if it's a survival mode that they are in.

As a suggestion if you can:
Maybe divide up their tank so that each individual crab is isoed, with tons of proteins offered daily. This way, they may calm down since they are on their own= no competition for food. It might give them a real chance to wind down and see that things are now different for them. You could leave them this way for a week or two and see if the behavior improves. I would bathe them before removing the barriers just in case there's a chance that they may smell different.