Emerald Crab Missing Claws


Premium Member
I noticed several days ago that one of my emerald crabs is missing both front claws and maybe a leg. Maybe he got into it with another emerald crab or one of my fish. Every night I've been rubber-banding nori to a piece of rock and placing it on the sand near where he hangs out. He really goes to town on it, but I don't know if it's enough to keep him going until the claws grow back.  I thought about trying to catch him to put him in a little 5-gallon tank I have running now in case he's being bullied, but I don't know whether I'd be doing him any favors.Anyone ever deal with something like this? 
I've never had or heard of this. However I do know some invertebrates will regrow "claws". My main reason for "chiming in though is; are you checking your tank late at night with a red light for "apex" pests?
Thanks for chiming in, BrianC.  I haven't seen anything like a mantis shrimp or similar. As far as I know, the only critters in my tank capable of ripping the claws off an emerald crab are the other emerald crabs (some are quite large) and maybe my clowns. I've played tug-of-war with an emerald crab a few times trying to retrieve a rubber-banded rock, and they're actually pretty strong. I usually do my "late night" viewing within an hour of lights out and sometimes in the morning.  I don't have a blue light.  I saw the Orphek Azurelite on Amazon for $30.  Is that a good one?  Is there anything cheaper that you can recommend?Incidentally, the clawless emerald crab actually seems to be doing ok for now.  It regularly comes out to feed when I place some seaweed near it.  It just uses one of its legs to shovel it in. It spooks easily though. 
E crabs are really strong, almost sounds more like a power head incident.  I know Coral banded shrimp will bite each others legs off when two are in a tank.  Don't pay 30 bucks for the Azurelite.  I bought a generic version of that light for 9 bucks on Amazon.  Works great.  That's how I spotted Nudibranchs on my zoas.  Here's a link:https://www.amazon.com/gp/product/B01C2D7SRA/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1 
... a power head..... I am not sure a power head would have lived through it with there soft plastic propellers. Um, crabs in tanks frequently rip off legs and claws of the same species... especially larger more alpha same species - totally possible.  I am 90% certain claws will regrow not sure about feet. but would remove him from where he was.
Thanks, everyone. I don't think it was a powerhead simply because I don't see how he could have reached one. Both powerheads are a decent distance from the sand and rocks.If I can figure out how to trap him or see an opportunity to net him, I'll move the crab to my 5-gallon tank until his claws grow back. He's still pretty quick though, and he hangs out near my clam, which I don't want to take a chance hurting, so no promises.I ordered the flashlight you recommended. Thank you.