Is This A Bad Hitchhiker Crab?please Help...

[KittyKat]

I have this black crab in my tank that hitchhiked from the LR. Is this a bad crab to have in my tank and whats the name of it? Does anyone have any more closer pictures of this crab? Currently in my tank I have a few corals(open brain,donut coral,frogspawn,torch coral,colt coral, 2 different types of finger leather corals,some zoos and mushrooms, 2 fishes, about 6 hermit crabs, I did have 2 snails but I just found an empty snail shell with no snail in it, a cleaner shrimp, and a sand sifting sand star. When i was adding a new live rock in my tank i saw it come out but it ran away real fast and tonight I finally saw him posted up in one of my live rocks. It has been over 2 weeks since i last saw him and my main concern is if this hairy crab is going to do some damage to my reef tank.

I'd appreciate any info or advice on these hitchhikers. It really looks very very similar to WITFULL's pic he posted. Here's the link of the pic that he posted on this thread:

Thanks for any help.I'm a newbie in this and so far i'm loving it but there is always something new i learn about my tank everyday and today it was this mysterious crab hiding in my live rock.

3/22/08:This morning i saw the crab just a little bit and it looked like he was eating algae and whatever else he was picking off the rock he has been living in. I saw one of my hermit crabs come very close to him and he did not do anything to it so maybe he's not so bad to keep? Id really appreciate any help on this.

Thanks again!

 

[goldenmean]

Crab Hitch Hikers

it is hard to ID a crab with out a pic but as a general rule of claw.
If the crab is hairy it is a danger to reefs
if a crabs claw is black and pointy it is also dangerous to a reef tank.

 

[framerguy]

I have what can only be described as a "black" emerald crab. It looks like an emerald in everyway except color. If the claw has a flat, round tip it is designed to eat algae, and "should" be OK. As with everything concerning living creatures, there are good ones and bad ones, and ones that have been good can turn bad. I have kept a very close eye on my black emerald, and you should too, and remove it at the first sign of unwanted behavior. Try to get a photo of it for a definate answer though.

 

[KittyKat]

Here is a picture of the crab, thanks everyone for the help.

 

[rlf_racing]

That crab is still not safe. There is also nonreef safe crabs that have cupped claws. I would still banish it to the sump.

 

[lcstorc]

You mentioned that yours was hairy. Regardless I woild remove it to the sump or fuge. The only crabs allowed in my tanks are scaarlet hermits.

 

[theshawfamily5]

I had this same black emerald. He was 2". Always shy... even at night he could pick you out hiding in the room. I watched him for many nights... always eating at algae on the rocks... Never agressive to anything, and always hidden in the day.
I killed him on the 3rd inteceptor treatment for bugs... He did just fine on two ... with a couple of weeks between. I have never been more upset.
He was the coolest crab in the world.

The pinchers are perfect round disks and he moves like the wind.

keep the boy... if he is still in your tank.

They are quite rare and I havent seen on since.

 

[TheRedWater]

Hey,

so I've got a reef tank with some fairly delicate fish in it right now and I've spotted my own little black crab invader. I described it to the very experienced owner of the local fish store and she warned me to kill it right away. Mine sounds the same, black with hairy legs and you usually only see his claw eating algea. However, the lady said she had the same one in her tank, but they're dangerous to rock sleeping fish, and other hermit crabs if it's hungry. Apparently hers ate two(2) of her Purple Firefish. I have a very well acclimated Longnose Filefish in my tank and I can't risk it getting eaten in its sleep. So, just a warning to you and any others, I don't know that she's right but take it under advisement. Mine is a little more social and comes out of the rocks when it thinks no one is looking. Its about an inch and a half wide with its legs and I am about to remove it just in case.

 

[charlesr1958]

That species of crab is a fairly common hitch hiker for me and over the years I've learned that while they are somewhat small, they tend to be content with just scraping the rocks for algae and possibly other small sessile life, but once they come of age they can and will go after larger items such as zoanthids. I would remove it if given the chance.

Oh, and thanks to whomever was trying to link to my hitch hiker pages, but the web address has changed :

Live Rock Hitch Hikers

Chuck

 

[seahorse630]

I have a delicate, expensive seahorse and i found a black crab with hairy legs. it was pretty big though, almost 3". i pulled it out with tweezers and put it in a water bottle filled w/ salt water and brought it to the pet store i got my seahorse from. they told me if i wanted to keep it, i had toput it in a seperate tank with a filter and some live rock. i did all that they said and it seemed to be fine. i now have 2 salt water tanks, one w/ my seahorse and the other with all the hitch hikers (including the crab) and they are all looking happy!