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FAQs about Marine Crab Identification 3

Related Articles: Crabs, Hermit Crabs

Related FAQs: SW Crab Identification 1, SW Crab ID 2, 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,

Emerald Crab...black? 09/01/08 Hello WWM Crew! Just curious what this crab is that I seem to have. He came along unexpectedly with one of my corals that I purchased about 6 months ago. He was quite tiny - about 1/2" or so - but just looked like a little emerald crab - same shape, hairy legs...but seemed a little darker in color. I didn't see him again in the tank and figured he didn't make it...until about 3 or 4 weeks ago when low-and-behold...there he was! MUUUUCH larger now...about the size of an adult Emerald Crab....only pitch-black in color. Green Emerald Crabs are quite common in every fish store I've ever been in, but I've never seen a variety that is black. Any idea what I have? Just an odd-ball colored variety of the Emerald Crab? <It is likely some species/variety of Mithrax crab. Sorry, but without a pic I honestly can't tell you much more than that... :-/ > I'd send a picture, but the only times I've seen him he's hiding between the rocks. Thanks, Chris <Do keep an eye on him... Best,
Sara M.>

When In Doubt, Take It Out 09/15/05 Ted, <<Hello Rebecca>> Thanks for all your help and advice to date. I checked the Stomatella snail and it looks like a match thanks! <<You're welcome.>> I've searched all I can on your site (and a few other  linked ones) but have not found a definite match for a crab that seems to also be a hitchhiker and after reading your comment that many crabs may be a problem...wondered if you could help (again!) <<I'll try>> Percnon gibbesi, the Nimble Spray Crab. Tropical West Atlantic. Live in reefs, rocky areas. Hide under Urchins and rocks. THIS IS THE NEAREST PICTURE ON YOUR WEBSITE I CAN FIND BUT MINE LOOKS A BIT DARKER BROWN POSSIBLE & I HAVEN'T MANAGED TO SEE IT IN FULL. Initially I thought it was a hermit crab in the rock. It is the same size and shape as our blue legged hermits...(but without the shell) however as it is in the rock, I've only managed partial body sightings. On several hours more staring, it is dark brown, with paler bands down all legs. The nippers are, pale/flesh coloured and small (it seems to be all legs with pointed claw-like fine ends like the hermits) and it seems to be an algae grazer. I'd estimate it at no more than an inch in diameter. We bought hermits and also a large decorator crab, but this one is definitely not one we bargained for! It seems to stay in the same area. I don't know whether my description is detailed enough so should I try and catch it? How would I go about that? I hope it doesn't end up having red eyes like some of those I've seen on your website. There are some monsters aren't there.<<Identification of a crab can be difficult. I would move the crab to where it can't hurt fish or corals and observe it.>> Thanks again for all your help to.. I hope you get paid a lot for all your wisdom! Rebecca <<You're welcome. I'll talk to our Union Rep about a merit pay increase. Good luck- Ted>>

Mystery Crab - 08/11/2005 Hi <Hello.> Today I Purchased some live rock and in it came out a really sweet little bright red crab around 1inch across and scarlet red in colour have you any ideas what it could be.  It buried itself in the sand substrate.  The rock is Fiji rock. <Many, many possibilities....  See here for starters:   http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm . > Regards,  Charlotte,  In the UK <Wising you well,  -Sabrina, in sunny silicon valley, CA, USofA.>

Red crab....  possibly from Fiji.... ? 8/13/05 Hey there, Bobster.... Quick question.  The gal with a (very) undetailed crab ID request yesterday has replied, and given a (slightly) more detailed description....  Wonder if you can point me in the right direction.... <Saw this... and with the provided info... don't know...> She say it has roughly the shape of Cancer antennarius . It has elongated black eyestalks and black "joints". It is currently about an inch across. The crab has burrowed into the substrate, and come back out again. It came in on Fiji live rock that she recently added, but I am not at all convinced that that means the crab originated with the rock from Fiji.  Don't know. <Me neither> Anyhu, the elongated eyestalks thing and small size, as well as burrowing, makes me think Uca/fiddler-type crab....  a couple red ones I know of/have seen.... but I really don't know. Any thoughts? -Sabrina <Really am at a loss... not an unusual state here... I say (re such crab unknowns), "When in doubt, take it out" or at least keep a keen eye on it for opportunistic predation. Cheers, BobF> Mystery Crab - III - 08/12/2005 Dear Sabrina, <Hi, Charlotte!> The crab I have looks very much like Cancer antennarius although it is very small and scarlet red not brown. I present it is about 1inch across.  The crab has finally come out of the sand substrate. It is still bright red with a smooth shell, the eyes are on long black stalks also it has black joints.  Hope this is still some help because there was nothing like it on the list you sent other than the one I labeled. Regards Charlotte Windsor <This description is of some small help, but unfortunately, just not enough for an accurate ID....  You might google for images of genus "Uca", but I do not know if that will be fruitful at all.  I asked Bob his ideas, as well; he, too, is at a loss.  He suggests " 'When in doubt, take it out' or at least keep a keen eye on it for opportunistic predation."  So do be wary of it - were it me, I would probably set up another small tank for the guy, should he prove to be a problem.  Wishing you well,  -Sabrina> Mystery Crab - IV - 08/12/2005 Hi Sabrina <Hello, Charlotte.> Would a photo of the little guy help ? <Mm, not terribly likely, but it sure wouldn't hurt!  We may *possibly* be able to nail it down a little....  Worth a shot.> Charlotte <Wishing you well,  -Sabrina>

Crab ID 7/28/05 WWM Crew <Mike G> I have spent hours looking for what the ID of the crab <Good luck. Crab identification is very difficult, indeed.> I have in the attached photo is, and anything that I could find out about it. <I'm sorry, we didn't receive a photo.> I have a 125 gal, some coral reef with 100 lbs of live rock and a few fish, he appears he could be a mean little fellow, and I do not have any idea how big he will get. <In general, I don't trust crabs. Guilty until proven innocent is what I think of em. I'd isolate him until you can prove him either innocent or guilty.> Thanks for your help in advance <Welcome.> Mike Re: Crab ID 7/28/05 Sorry I did not attach the first time, thanks for your timely first response, maybe you can give me more info with this, thanks again, Mike <Still did not receive it. Mike G>

Hitchhiker Crab; I am not sure which it is; hair algae and do you know Kenny Doubt, aka 'Sharkbite'? 7/17/05 Hello Bob. <James> I made a discovery as I brought my live rock home from my favorite LFS the other day. I now have another crab. I was fortunate not to have put my fingers into the hole he was hiding in and noticed it while I was examining the rock. It is somewhat large and I estimate nearly an inch and a across the carapace. It is black or a very dark green and the joints appear white. I am not certain, nor is the owner of LFS, if it came from his tank or not. This is because we got rock from both the holding/curing area and then some from a main tank. This specimen neither seems to bother the skunk cleaner shrimp, which I transferred in from the 5 gallon, nor the red scooter blennies. How do I go about looking up what this crab is? <Mmm, a pic... the Net... sending out to forums that deal with such> I do not see it much but I know where his hiding spot is. It seems to be content to pick at the rock and only raises its claws when anything gets into its comfort zone; standing ground but does not appear overtly aggressive. I am going to try and catch it and bring it to the LFS to see if he can identify it. If it was in his tank I will probably keep it and pay him something extra as it has lived peacefully in that tank for years and did not bother the fish that are in it. If it is not his then it is a mystery and came from the tank he broke down from a customer and I think not worth the risk.   I also made a discovery in that the branched coral (somewhat obviously now is coral) looking rock had corals coming out the tips. They are red and dark purple, bubble-like in appearance. This is going to be somewhat more of an issue as unless I can get a decent picture I know if I remove it from the tank and take it the store odds are good it will be a day or so before they will open back out. Besides, I do not wish to stress them. I do want to take care of them properly and I feel that is easiest a task if I know just what they are. I was speaking with JJ Perez the other day at his store in Ridgefield Park, NJ. We thinks the problem (algal growth) I have is with phosphates and hard Garfield water. He mentioned the hardness of the water (he measured at about 550ppm KH a while back) <Yikes, liquid rock!> was great for breeding African Cichlids. I have limited the lighting time periods and tried reducing feeding. I have been diligent in trying to pick as much of this hairy nuisance as I can off the rock but unless I get it out it just sticks elsewhere. We (my wife and I) have decided on getting a small RO unit but have not yet. The Mithrax crab is not doing his job in the 5 gallon tank as the Royal Gramma pursues him mercilessly once he is seen out of his hiding spots deep in the rock. The cleaner shrimp was removed as the fish was constantly picking at him though I would have preferred to wait to add him into the 55gallon tank. It is nice to see him no longer forced to hide in the top corner near the heater all the time and this does make cleaning the smaller tank easier. I think I asked about Kenny in an earlier email (now like all things on my old drive) lost. JJ mentioned that he was a fish collector and worked at a distributor in Hawaii. I just thought he was a cool surfer originally from New Jersey. Small world indeed! <Don't know him as far as I'm aware... do think I've been to the NJ store with my bro-in-law Pat though.  Bob Fenner> Present (mostly constant) tank parameters: pH:       8.2-8.4 SG:      1.0228 (55 gallon) 1.0224 (5 gallon) KH:       upwards of 300ppm (see JJ's measurement above) NO2-:    0ppm NO3+:   15-20ppm (55 gallon) 20 ppm (5 gallon) Temp:   78-79F average. Gear on the 55 Gallon: 260 Watt Coralife power compact, Aquaclear 1100 filter and a Penguin 1140 Power Head (directing flow diagonally towards the front of the tank) mounted on the left end from the filter which is on the right/middle side. Prizm protein skimmer not hooked up yet (I am thinking of placing it next to the filter if it will fit) as per recommendation (wait three weeks) from using stress coat to treat the tap water for metals and Cl ions. Oh, yes I am running everything off a GFCI… Stanley makes a good one available at Home Depot and it has 8 plug inputs for about $27. I am also going to get a UPS… because you never know when you may not have power… Any suggestions on things I should change or add? Thank you for making such a great website and providing so much great information in your book (wife calls it my 'fish bible', lol) Bob. James Zimmer

Unidentified crab type creature Hello All, I just bought a yellow and purple double sea-squirt from live Aquaria.com (Polycarpa aurata). It came with some interesting hitchhikers on the small rock it is attached to. What seems to be a Christmas tree worm or some such double barreled triple banded fan worm. However, what I am interested in ID'ing is some sort of crab I think. Unfortunately it is much too small for me to get a picture of (I need a telephoto lens). There are at least 5 in close proximity. They live in very well defined holes. All that sticks out is a pair of eye stalks, somewhat like a hermit crab, two long antennae, and some funny pincers. One is predominately larger than the other, but both are very flattish with a purplish color and small white spots that blend into coralline algae as great camouflage. The pincers are very flat and kind of wide and bladelike like a canoe paddle blade. They have a funny behavior of resting their pincers hanging out the edge of the hole like they are relaxing on their balcony or something.  All of them do this. Again, all I can see are the eyes, antennae and pincers. The whole critter is very small.  Because of the shape of the whole its body must be more tube like than a typical round crab shape.   The pincer length of the largest one is only about 2 mm. The antenna are maybe 4 mm's in length. I don't know how long the whole crabs are because they won't come out of their hole. Anyway...any help would be appreciated...Collin >>>Greetings Collin, Even if I were the worlds foremost crab expert, I could hardly hope to identify the species you have in your possession with such a description. There are THOUSANDS of species, positive identification is often difficult even with the best of photos. In all likelihood they are harmless, very rarely have I had problems with crabs unless they were fairly large. Cheers Jim<<<

Caribbean Crab ID Greetings, I am seeking assistance in identifying a crab that surfed his way in on a piece of Caribbean live rock.  We have seen glimpses of him here and there, but never enough to know whether we had a Mantis Shrimp or something else.  We were finally able to get him out of his hole, and were surprised to see a crab.  If he is non-threatening, I will return him to the rock.  Currently, we only have Astraea snails, Nassarius snails, Blue-leg Hermits, and a pair of Yellow-Tail Damsels. Thank you in advance, Brian Domke >>Hi Brian. I don't actually know what it is, but a good rule of thumb is not to put it back in the tank. Most crustaceans are opportunistic carnivores and probably will, at some point, eat something you want. Rich>>

Filter feeding crab hey guys the other day I was strolling thru the LFS and noticed this crab that had arms that were modified for filter feeding (really cool) I couldn't keep my eyes off it.   of course the employees didn't know what it was, any ideas? << An anemone crab, maybe a Neopetrolisthes maculata. >> thanks, Ryan <<  Blundell  >>

Crabs... never truly reef aquarium-safe 8/31/04 Hello. Please look at the attached photo (sorry, quality suffered due to distance through water) and tell me if this is friend or foe. It is a small crab, about 2 cm, dark brown smooth carapace with even darker brown claws that are tipped with white. Walking legs are light brown and very hairy. Thanks, as always, George. <crabs are almost categorically opportunistic predators (omnivorous). There really is no such thing as a reef aquarium-safe crab. And in specimens like this with large claws... form follows function. Those aspects exist for a reason/application (catch/kill). Remove the crab to play it safe... best left in a larger fish only system to scavenge in. Kindly, Anthony>

Hairy Crab... not reef-safe 8/25/04 please could you identify this hairy crab for me! I think it is responsible for killing turbo snails and shrimp. many thanks, Chris <while we cannot ID this crab by species... we can say that it is almost certainly not reef-safe and is a very likely candidate for killing snails and other desirable reef inverts. As a rule, true crabs are not reef safe at all... they are opportunistic predators at best. Do remove this crab to a large fish-only tank for employ as a hearty scavenger. Best regards, Anthony>

Crab Identification 19 Aug 2004 <Hi Brian nice to meet you, MacL here with you this afternoon.> I purchased two small crabs from LFS. They are bright red with blue eyes that are extended away from the body. They have tiny claws that are even in size. No banding or striping on the body, just solid red. As soon as they hit my substrate they burrowed into the live sand and have only been seen once since (about a week ago). LFS sold them as fiddler crabs. <Fiddlers males generally have one claw that's larger I believe. But you could have two females.>  Have no reason to doubt that, but can't seem to find any information on line the identifies them as such, nor fiddler crabs that are exclusive to life in the water, not on land. <Have you been through this http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm to see if anything looks similar? My first thought was a pink Mithrax crab (least that's what they are sold as around here)> Thoughts? Identification? Resources? <Take a look at the threads off that site and see if you can identify it.  Good luck, MacL> Thanks!
Brian Bengtsson

Flame Box Crab or Shame Faced Crab photo I searched high and low for a better picture of this beautiful and unusual crab.  I offer this one for your site. Hope you like. Thx. M. p.s.  Photo taken Captiva Island, May 2004 <Very nice image. Thank you for sharing. Will post with credit to Miles Nixon. Bob Fenner> Miles J. Nixon

Unidentified crab <Hi Cyndi, Mac here> Please help!!  We have found a tiny crab living in our live rock.  <Not always a good thing, some crabs can cause some troubles.> He is about a 1/2 an inch wide from left leg to right leg and they are hairy looking. <Cyndi, could that be feathery and not hairy?>  He is white and appears to have small purple spots on each joint.  He has more purple stripe like markings on his back and his eyes appear to be purple. He moves kind of slow and generally stays in a little alcove on top of a large rock. <Just from your description, its possible he might be a type of porcelain crab similar to Neopetrolisthes maculata or possibly of the Lissocarcinus family>  I can't find a picture of one like him anywhere on the net. <There are many wonderful sites that have some pictures of crabs.> I may be able to get a picture of him out of our aquarium if you can't tell from the description.  <A picture would be IMMENSELY helpful.>  Thanks in advance for you help. C.S.

Is this a dangerous crab for my reef Hi, I recently noticed two crabs in one of my large Acros.  They seem to be eating the tissue.  They are hairy brown crabs.  With little claws with dark tips.  They're body is about 1/3rd to 1/2 inch in size.  Do you know how big they will get? << I'll bet not much bigger than they already are. >> I've tried putting a small glass with some meaty (clam,  mussels and shrimp) food, but I can't seem to catch them? Any idea? << I've heard of people skewering (if that is a word) them with a toothpick.  Also, you can continue to try luring them out.  >> They seem to live in my Acro which is at the top of the rock work?  Someone told me it might be a Gorilla crab?  Should I be trying to remove them?  << I like crabs, but then again I like corals more.  So you may not need to remove them, but just to be safe you may want to.  Another idea is if you can easily remove the coral, then take it out of the tank (crabs and all) and put it in another small container.  Here you can shake them out or use tweezers.  Better safe than sorry. >> Christine Trudeau
<< Good luck, Adam Blundell >>

Mystery Crab - 03/15/2004 Hi, we love the site, it has been very helpful.   <Glad to hear it.  Sabrina here, at your service.> We have a 55 gallon tank with a yellow tang and some damsels in it.  We recently added some shrimp "coral banded and a peppermint" they get along well.  We also got a rather red crab.  It said on the tank it was a fiddler crab, but we are not sure. <Did the fish store have the Latin name for the crab, perchance?> We can't find anything that looks like it on your site.   <There certainly are lots and lots and LOTS of crab species in the world.> He/she is very red/orange and is the size of a quarter and we never see it.  He or she hides under the live rock. <You might be able to get it trained to come out for food, if you target-feed with a turkey baster.  It would take a while, but crabs can become very, very outgoing.> We just don't know what it is for sure. <Neither do I, without a picture, I'm afraid.> Are our fish in danger? <Tough to tell, without ID'ing it.  However, at such a small size, and with active, fast moving fish, I don't think there's a whole lot to worry about.  The shrimp would be at more risk than the fish, and even still, they'll likely be fine.> We're very new at this, need some advise - he/ she doesn't look like your pics. <Speaking of pics, if you can snap a digital photo of him and email it to us, somebody may be able to give a positive ID.  Wishing you well,  -Sabrina>

White crab inside scallop 2/14/04 Recently I've noticed that the orange on this inside of my electric flame scallop was deteriorating. <regardless, this is a very poor specimen for captivity... most slowly die within one year of purchase. Please do resist buying another> I thought that it was either normal or maybe the scallop was dying. Well today my scallop turned around so now I can see the complete inside. But I found a crab inside! Can you identify this crab and tell me some more about it? <not really without a picture or detailed scientific description. Else you are asking us to name a faceless creature <G>. Kinda tough> I think my scallop may be doomed, but this is a cool looking crab. <the carb may be commensal, obligate (if so he will die soon too) or simply a hitchhiker. Hard to say. Agreed though... fascinating> Thanks so much and I love your site! -John <best regards, Anthony>

Mystery crab 1/11/04 Well lookie what just materialized in my tank ;) Just about two months in, no fish yet and I am constantly amazed that no matter how long I stare at my tank something always shows up I hadn't seen before.  This guy showed up yesterday, I have him (or her) in holding and I am planning on taking him to the LFS unless you folks give this crab a reprieve.   <no crabs are truly reef safe. And one look at the claws of this guy rules it out promptly. Form follows function. Those big, sturdy claws are there for a reason/purpose... and its not/only for scraping microalgae. Desirable animals in the tank will likely be at risk in time> The tank is basically a FOWLR that will drift toward reef, I already have some zoo's that came in on live rock.  As a matter of fact something has been eating them lately (I have been following the similar thread here with great interest) do you think it could be him? <it is quite possible> I have ordered Reef Invertebrates - in the meantime - any ideas on an ID?   <not really... there are thousands of possibilities> I should add this crab is about the size of a penny. <for now ;)> From what I can glean from the Crab ID FAQ's the verdict is almost always remove the crab - any reason I should keep him? (besides the fact that he's kinda cool) <they are usually hardy and entertaining. great for tanks with larger fishes. Keep him in your sump or refugium in the meantime if you will feed it> Thanks for the site and your reply, I'll be here lurking in the Daily FAQ  Arnold <with kind regards, Anthony>

Crabs inside of live oysters I recently  bought some live oysters from the supermarket and while shucking them I found small crab inside that was still alive. I was wandering what kind of crab this would be. the oysters were farmed raised in Weens Va. can I put this little crab in my fish tank ? <Might be the commensal Polyonyx gibbesi> will it adapt to fresh water? <Not likely> if it survived all of this I don't see why I cant keep it alive until spring when I can take it back to the bay. I accidentally brought home a fiddler crab from the Florida keys in a plant and kept her for two and a half years until I returned back to sunshine key to release her ! <Neat!> what a wonderful experience. she was the size of my pinky fingernail and when I released her , her body was the size of a quarter. she had shed her shell several times in a shallow bowl of water. even during the full moons. I kept all of her shells. please let me know how I can collect information on this subject. sincerely, Margie Petro <Do try "plugging in" the above scientific name in your search engines and seeing if this is the animal. Bob Fenner>

Odd Crab 1/2/04 Sorry I didn't have a program to resize these.  Paint wouldn't let me. So, I'll only send 1 unless you want more. Info on the crab. Found along Florida Gulf Coast area (Tampa) Looks like a rock with legs and pincers. About 1 ? inches long. Narrow end of "shell" is where his eyes are. The shell is NOT an attached rock as his eyes are "built in" Any ideas? <cheers, Larry... your crab is "sponge crab" of the family Dromiidae. They are often decorator species, and they are never "reef safe" (very few if any crabs are in fact). Some sponge crabs have specialized diets or feeding habits. Survival in captivity is variable and runs the gamut. Best regards, Anthony>

Re: Odd Crab ID 1/7/03  Anthony, I don't doubt you, but while searching on Dromiidae or sponge crab, every web site gives me this:  http://www.ciesm.org/atlas/Dromiaspinirostris.html  Or a very similar shaped crab.  <you are looking in the wrong place/ocean here my friend. Your crab did not come from the Med or coast of Italy... unless you can confirm that he is as hairy as I am and likes nearly as much garlic on his food <G>. The Dromiids are an enormous group with a remarkable number of species. You need to look at references in locales where your live rock/coral has come from. Most of these crabs come from the Atlantic. Often with live rock... other times collected deliberately ten stocked in dealers mixed holding systems and "hitch-hike">  This crab does NOT have anything on top of him  <the crab in your link above is indeed nothing like your>  The rock looking shape IS his shell, not something he's holding on to. >From the items I read, the back 2 legs "hold" items, but this guy's back 2 legs are normal, not sticking up. Any links on the net to a similar crab? Thanks again  <your crab truly is a sponge/spongy decorator/spider type crab. Look to Paul Humann's "Reef Creature" book and you will see your critter. Best regards, Anthony>
Re: Odd Crab ID 1/8/04 Anthony, Thanks again. <<always welcome my friend>> <you are looking in the wrong place/ocean here my friend. Your crab did not come from the Med or coast of Italy... unless you can confirm that he is as hairy as I am and likes nearly as much garlic on his food <G>. I'll have to try that.  Lasagna and spaghetti with garlic bread probably won't look very good in a salt water tank though.....  :) <<true... but the skimmate in the skimmer will be remarkable>> <your crab truly is a sponge/spongy decorator/spider type crab. Look to Paul Humann's "Reef Creature" book and you will see your critter.> Thanks for the tip and advice.  We'll look for that book!   <<The Humann series of books overall is amazing and well worth it. DO look at them all>> It's amazing. I've studied computer science, space science, earth science, mathematics and such, but the earth is so covered in ocean with such diverse life, that humans don't spend more time studying it! <<so true... the density of life in a square inch is simply staggering. In shared admiration of the sea, Anthony>

Crabby Hello again, <Hi Steve, Adam here at your service.> I have recently discovered a small crab that either came attached to some indo-pacific live rock or Fiji.  I am coming to realize that this is not overly uncommon. <Very common actually.  In fact, my tanks have been set up for years and I just discovered a new crab a couple of weeks ago.  They can also hitchhike on corals.> I have no picture for you, but I can tell you his body is purple, his claws are as well, but the claws have white tips on them.  his legs are zebra like (black, and whitish yellow stripes).  his complete body (including legs) is probably a little smaller than a penny or dime. <Providing any reliable ID from your description is impossible.  And as you read on, the ID really doesn't matter IMO.> I understand that most, if not all are dangerous tank species.  I was just wondering how dangerous this guy would be to my corals such as: xenia, button and star polyps, mushrooms, and tree corals. <You are absolutely right.  Many aquarists have learned the hard way not to trust any crabs (even the supposedly "reef safe" hermits, emeralds, etc.).  This crab could be around for a while without causing noticeable damage...  until it is the size of a quarter or half dollar.  Also, most crabs aren't neat and considerate.  If they are hungry, they don't pick an apple from the tree and eat it (so to speak of course), they knock down the tree, break all the branches, take bites out of a few apples and then smash the rest.> I would like to keep him as long as possible, as I really like him.  Any and all information that you could supply me with will be greatly appreciated. <Can you tell that I am not a crab fan?  If you choose to leave it, watch it carefully and try to target feed it.  If it isn't hungry it will be less likely to be destructive.  When you do decide to remove it, a baited beer glass placed upright with the rim against a rock near where the crab hangs out makes a very effective trap.> Thank you for the great web-site etc.  and I'm sure I will talk/write to you again.  Again thanks for all the help. <Thanks for stopping by!  I will look forward to chatting again.  Adam> Steve

Crab ID please 9/29/03 Is a "red ridged clinging crab" reef and clam safe? <like the green cling/emerald crab Mithraculus sculptus... M. forceps, the red cling crab, is not entirely reef safe. Most all crabs are opportunistic omnivores. With abundant algae in the tank, they appear to behave... but in lean times, the will prey on desirable reef animals. Anthony>

Crab ID please 9/29/03 Is a "red ridged clinging crab" reef and clam safe? <like the green cling/emerald crab Mithraculus sculptus... M. forceps, the red cling crab, is not entirely reef safe. Most all crabs are opportunistic omnivores. With abundant algae in the tank, they appear to behave... but in lean times, the will prey on desirable reef animals. Anthony> Red cling crab removal 9/29/03 Any suggestions on how to rid my tank of them.? <they can easily be lured with food in a sunken jar at night... their pointy legs do not allow scaling the glass walls of a jar easily for escape. There are many other suggested methods for trapping creatures in reef aquaria in our WetWebMedia archives... please d o a keyword search(es) from the home page with the Google search tool. Best of luck. Anthony>
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