Need a Crab ID

[Hartdude]

I found this crab living in my tank a few months ago. I assume he hitchhiked on some rock or coral that I introduced around that time. I'm sorry that the pic isn't the best, but I'm here to tell you that this guy doesn't like his photo taken. It has spots similar to a Porcelain Crab on its carapace, but very hairy legs. As you can see its chelipeds are lavender and yellow in color. Any ideas? I'll continue trying to get better photos, this is a pic my wife snapped for me today while I was working.

 

[AJSTITAN14]

it looks like some sort of Xanthid Crab or Stone crab. It's hard to tell since he is hiding and I bet he will only come out on his terms. If you never see him waving his arms to feed then hes not a porcelain.

 

[a.stebel]

What color are the crabs claws? Seem to be hidden in the picture. His body shape is very similar to a gorilla crab I have.

 

[sedor]

If its got black claws get rid of it. Personally that spotted pattern is making me think its a porcelain, but its hard to tell without seeing the claws.

 

[Hartdude]

I don't think it is a porcelain crab. I've never seen it waving its maxillipeds, heck, I rarely see it anyhow. I think the tips of his claws are black. Sedor, I wish it would come out so I could catch it!! He certianly would inhabit my sump if ever caught.

 

[LeslieH]

Guys, it doesn't matter what color the claws are. Black doesn't mean anything.

 

[Hartdude]

Guys, it doesn't matter what color the claws are. Black doesn't mean anything.

Dr. Shimek over on MD's forum identified it as a Black Tipped Xanthid crab. He says it should be removed as it will grow quickly, and is an omnivorous predator.

Looks as though I'll be making a trap this evening!

 

[LeslieH]

Dr. Shimek over on MD's forum identified it as a Black Tipped Xanthid crab. He says it should be removed as it will grow quickly, and is an omnivorous predator.
Looks as though I'll be making a trap this evening!

Didn't you say that the chelipeds were lavender & yellow? :lmao:

"Black-tipped crab" is a common name used by reefers for this family because some - but not all -of the more common hitch hiking xanthids have tips of this color. However, there is no relationship between having black-tipped claws & being a menace or even being a xanthid. Some safe crabs have black tips & some dangerous ones don't.

Most crabs are omnivorous but that just means they are capable of eating anything, not that they will. The other day I was checking some references on toxicity in xanthids. Much to my surprise I found several studies that showed the ones studied were primarily herbivores. The list of species included some of the most common hitch hikers we see. The percentage of algae in their diets varied according to the season & geographic area but algae was always the predominant food, supplemented on occasion by worms, gastropods, small crustaceans, sessile organisms, dead critters, and detritus. The toxins in their systems didn't come from zoanthids but from marine bacteria & dinoflagellates associated with the algae & other food items. That explains why many reefers have reported having xanthids in their tanks for years without any real damage. Maybe we need to take re-evaluate the common prejudice against crabs.... well, against xanthids anyway!

 

[Hartdude]

Didn't you say that the chelipeds were lavender & yellow?

I did, but the very tip of them is black. :rolleye1: