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FAQs about Marine Crab Identification 6

Related Articles: Crabs, Hermit Crabs

Related FAQs: SW Crab Identification 1, SW Crab ID 2, SW Crab ID 3, SW Crab ID 4, SW Crab ID 5, SW Crab ID 6, SW Crab ID 7, SW Crab ID 8, SW Crab ID 9, Marine Crab ID 10, Marine Crab ID 11, Marine Crab ID 12, SW Crab ID 13, SW Crab ID 14, SW Crab ID 15, SW Crab ID 16, SW Crab ID 17, SW Crab ID 18, SW Crab ID 19, SW Crab ID 20, SW Crab ID 21, SW Crab ID 22, & Marine Invertebrate identificationMarine Crabs 1, Marine Crabs 2Marine Crabs 3, Marine Crabs 4, Crab Behavior, Marine Crab Selection, Marine Crab Compatibility, Marine Crab Systems, Marine Crab Feeding, Marine Crab Reproduction, Marine Crab Disease, Micro-Crustaceans, Amphipods, Copepods, Mysids, Hermit Crabs, Shrimps, Cleaner Shrimps, Banded Coral Shrimp, Mantis Shrimp, Anemone Eating Shrimp Crustacean Identification, Crustacean Selection, Crustacean Behavior, Crustacean Compatibility, Crustacean Systems, Crustacean Feeding, Crustacean Disease, Crustacean Reproduction,

Hitchhiker ID (Crab)   1/3/07 Hey-    <Is for equines!>   I noticed this little guy about 4 months ago when I bought a rock with some hair mushrooms.  He was microscopic back then. <Wonder what it's been eating?>   I have since deployed to the middle east and when I was gone I had a very bad tank crash.  Somehow he survived and has in the last 4 moths... grown like 400X's.  I thought he was dead until last night when he was up sitting big a happy on a rock.  Do you happen to know what kind of crab he is? <Am guessing (from body shape) that this is some sort of Calappid: http://wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm a Boxer Crab...> I have a 29 gallon reef tank and don't want him to hurt anything. <... unrealistic> If he is compatible it would be good to have the knowledge about him to keep him happy and healthy. I research anything I buy very carefully.  Hope you guys had a great Christmas and safe and happy New Year.   Josh <Take a look on the Net re this family, the genera listed... Bob Fenner>

Pics of an unknown crab  12/30/06 This crab is about 1" across. The shiny things on him are reflections from the flash. Three pics are of the crab out of water, the one where you see the hairs are of him in water. Do you know if he is ok in the aquarium? He came with live rock that I picked up in Hawaii. At present I have  a fish only tank, but would like to do more. So would like to know this crabs eating habits. Thank you Dietmar <Hey Dietmar, JustinN with you tonight. Unfortunately, we did not receive your pictures with your email. If you have them in the body of the email, please try resending them simply as an attachment to the email, as we occasionally have problems receiving such. Sorry for the inconvenience! -JustinN>
 Pics of an unknown crab   1/3/07 I read somewhere on your site that you did not want attachments, so I sent the pics in the body. Oh well, here they are as an attachment. <Got 'em> I sure hope that you could ID the crab for me. It took me 4 hrs to find the silly guy, took all the LR and gravel out. In the end he was hiding in a hole in the LR. I was sort of attached to him, but want to expand and try keeping some easy corals and anemones. He only comes out at night. I was surprised one night to see him as he was a hitchhiker on the LR. I used a flashlight with some red cellophane over it an hour after lights out. <Good technique> Thank you Dietmar <Well... looks like either a Cancrid or Grapsid species... I do think you are wise to isolate, move this specimen here. Too likely a "midnight nibbler"... Bob Fenner>

Hitchhiking crab ID  11/25/06 Greetings crew: <Tim> Finally caught the little bugger who's been eating my snails and hermits, and actually caught him last night chewing on a live brittle star's leg. He hitchhiked along with some coral.  I initially thought he was no harm, possibly a Mithrax, but he's tripled in size over a couple of months, <Yikes> and has developed some bad habits, so he's going back to the LFS. <Good> Was wondering if you could ID him for me'¦ <Appears to be a Majid of some sort/species> He's brown to black in color with large claws (much larger than emerald Mithrax) now a good 2 -2 ½ inches across, and has a brown/black color with hairy legs, and scary red eyes.  I believe getting him out is best, <I agree> but was wondering if there is a specific ID, if he's obvious trouble, and how big he might get over time'¦. <Don't know... but you are wise to remove this predator> Pics attached'¦.
<Bob Fenner>

Re: Commensal crab?  ID   5/8/06 Well, <A deep subject> I finally managed to trigger the right "phrases" in my Google search, and found my crab, commonly known as a Red Coral Crab.  I think these crabs are commonly grouped into a category called "guard" crabs.  My pair appear to be Trapezia cymodoce commonly found in Stylophora. http://www.dafni.com/crustacea/Trapeziidae.htm More information is here as well. http://www.imagequest3d.com/pages/articles/trapezius.htm Thanks. Brett <A very interesting genus... BobF out in HI seeing these most days>

Crab Identification - 10/18/06 Hello Crew,  <Hi Stachia, MacL here with you tonight.> I am sure you have heard this scenario many times before, but here it goes. My husband and I recently found a mysterious crab in our 75 gal tank. We purchased 2 flame scallops a few weeks ago, went through all of the proper acclimation procedures, water tests were where they should be, nothing picking on them, and they died. The first died after about a week, the other died the night of the eleventh. <Honestly these are extremely difficult to keep alive. They are what I would consider an expert animal. Most people I know who successfully keep them have refugiums and aged tanks.> When taking the dead flame out of the tank, we found a strange crab inside it. It looked as if it ate most of the inner out of the scallop. The big question is if the scallop was already dead when the crab started eating it, and I guess that would depend on the type of crab it is. <Definitely, the right question. Did you see any signs of decline before it died? A crab can scavenge very quickly when its dead or dying.> I know that a picture can describe it better than I ever could verbally (writing), so I attached a few pictures, and have many others from different angles if needed. My local specialty fish store, who is very knowledgeable, has no idea what it could be, and I did not find any pictures on this site that seem to be even close to matching. I have typed every scientific name I could find for crabs into Yahoo and Google image searches and have come up empty handed. Help me please, we have it in a breeder box on the side of our 30gal invertebrate (no fish or coral) tank right now, and would like to let it go in the tank, but do not know what it eats or could hurt. <I looked at the pictures. I love all types of crabs and invertebrates and couldn't identify this one but it does look similar to sand crabs found on the Florida beaches. Those crabs could kill your scallops but honestly I think they were probably in a weakened condition from their stay at your local store.> When I shrunk the pictures down to a better e-mail size, they were slightly distorted. I do have a profile on the wet web forum, and actually asked for help a few days ago, but have not received any responses. <I just left a message saying you have mail meaning this.  Honestly we are all swamped trying to keep up with the emails.  We appreciate your patience and I'm keeping this email in my box to try to look for more with the crab so don't give up on us.> I try to be patient; I know everyone is very busy, but I do not know how long the crab will last in the breeder box. Anyway, my name in the forum is stace2001; I posted Mystery Crab on 10/12/2006 under marine invertebrates, and I have clearer pictures on my profile, along with descriptions. Thank you very much for your help, patients, and time.  <Thank you Stachia, Good luck, MacL> Stachia

Hitchhiker Crab ID...No Picture - 09/11/06 I have searched your site and many others looking for anything that resembles this creature.   It came on live rock that I received from Tampa Bay.  It is maybe ½' long.  In the picture its face is poking out of the water.   <<I'm afraid the picture didn't get to us>> Its face is not pointed and I could not get a picture of it from any different angle.  It was very interested in a small piece of sponge -- it chose the piece of sponge over Caulerpa or rock rubble to cling to.  I had posted a picture of this creature on two or three forums and the closest 'guess' was that it might be in the Pisidae family though the pictures that I could find had the correct body shape and the eyes were placed in the same manner but its face is not elongated as shown in the pictures of crabs from the Pisidae family. <<Might still be...from what I can find, there are some fourteen genera in this family>> I have removed the creature to our hospital tank as I didn't want it to go through the live rock cycling in our curing tank.  I would like to know what this creature is and possibly what it eats as I would like to try to keep it healthy and happy in our reef tank.   <<Most all crabs are too opportunistic for my taste, and some are downright destructive...I don't recommend keeping crabs in a reef tank.  An exception would be the small commensal crabs that sometimes accompany Acropora colonies, and even then they bear a close watch as not all of these are "safe"...is up to you to decide if you want to take the risk.  As for feeding, like most crabs/shrimp, this one will likely eat about anything (omnivorous) it finds (emergent life on your live rock) or can catch/overpower.  Regards, EricR>>  

Crab ID   8/30/06 Hello, <Hello> I found this guy in my tank a few weeks ago. Didn't think much of it until the area I saw him at just a few days ago was completely cleaned of all the polyps that were there. I found a similar looking crab (Gaudy Clown Crab) but to me it doesn't look like the same thing. If you could tell me what he is and whether he should be in my reef I would very much appreciate it. <Unless you do not like polyps, I'd remove.  It looks like a type of Calappa (Shame Face Crab), and not reef safe.  Bob may inject a more accurate description here.> Thank you, <You're welcome.  James (Salty Dog)>

Crab Identification  - 08/05/06 Hi Bob, Help Please !!! I set up a mini reef approx 12 months ago, I put in 80kg Fiji cured live rock. It seems though as if there was a hitchhiker (as pic). I have had approx 6 of these now. One seems to die and the shell drifts to the front of the tank so I think great safer without - "if in doubt have it out". Then another appears, this has happened 5 times now. I think I've finally seen the daddy !! its approx 4" across its back. I haven't had any fish loss but have seen damage to corals. Depending on your verdict, how do I catch the blighter ?? Your hopefully Jason <Mmm, a Xanthid of some species... Maybe a coral commensal... and likely no big deal. Please read here: http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm and the linked files above re compatibility/removal. Bob Fenner>

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