Did my urchin kill my emerald crab

[Miami Reef]

I bought a pincushion urchin and 2 emerald crabs last week. There’s lots of algae for them both.

Today I see my urchin carrying pieces of my emerald crab. I see some stringy things under the what appears to be the crab’s stomach area - looks like flesh. I see the claws too.

I don’t understand, did the emerald crab molt? Did the urchin kill the crab? Did one emerald crab kill the other and now the urchin is carrying the dead one?

I’m so confused.

 

[Sharkbait19]

I doubt the urchin would have killed it.
I’d guess it’s a molt because they do look suspiciously like dead crabs - but the fleshy area is a bit incriminating.
If anything killed it it would probably have been the other emerald.

 

[moz71]

I also doubt urchin killed it. I do have to rescue snails from urchin but crabs can usually fight off urchin. I agree it could be molt as I OFTEN confused molt for dead crabs. But could also be died before it attached to urchin. How long was crab in tank before this?

 

[bnord]

its hard to kill an emerald with a ball peen hammer, but it could be a molt, or it happened to app on
this look like a male, was the other one too?

 

[Miami Reef]

I collected the “dead” emerald.

I was able to find one of the emeralds alive but I can’t find the other one. I checked all the rocks in the tank.

It’s possible I missed it (they hide so well) but I don’t know. I’m thinking it died because I saw flesh (look at the video)

 

[Miami Reef]

 

[rmorris_14]

If it was just a little bit of fleshy pieces, it could have still been the molt. My husband and I both had a debate about a molt we found. It hadfleshy pieces around the joints, was still completely intact and was so convincing. I thought for sure my emerald was toast. Sure enough there he was two days later. And I had to tell my husband he was right. It was a sad day for me in our marriage lol. Hope yours has a similar outcome .

 

[Sharkbait19]

Found a crayfish molt in my fresh tank just yesterday that was super convincing (especially considering the other fish were picking at it). Shined a flashlight in the right crevice and there it was!

Emeralds are good hiders, I never see mine. Though that other one does look like a male - so aggression is possible.

 

[Miami Reef]

Found a crayfish molt in my fresh tank just yesterday that was super convincing (especially considering the other fish were picking at it). Shined a flashlight in the right crevice and there it was!

Emeralds are good hiders, I never see mine. Though that other one does look like a male - so aggression is possible.

You were able to tell that both crabs are male? How?

 

[Sharkbait19]

You were able to tell that both crabs are male? How?

Typically the males will have bigger claws. Though that isn’t a sure fire way to tell.
Looking at the underside would give a better picture:

 

[moz71]

Typically the males will have bigger claws. Though that isn’t a sure fire way to tell.
Looking at the underside would give a better picture:

Lol seeing those blue crabs reminding me of summer crab feast. Yum!! Lol

 

[shakacuz]

You were able to tell that both crabs are male? How?

@Sharkbait19 beat me to it!

 

[Miami Reef]

Typically the males will have bigger claws. Though that isn’t a sure fire way to tell.
Looking at the underside would give a better picture:

Haha

 

[CanuckReefer]

No, unless the crab was already dying.... my bet is on the molt others mentioned and in a day or two, hello long lost crab!