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FAQs about Marine Crabs 4

Related Articles: Crabs, Arrow CrabsHermit Crabs

Related FAQs: Marine Crabs 1, Marine Crabs 2Marine Crabs 3, Marine Crabs 4, By Species/Group:  Arrow CrabsEmerald Green Crabs, Decorator Crabs/Sponge Crabs, Fiddler Crabs, Pom Pom Crabs, Sally Lightfoots, & FAQs on: Marine Crab Identification, Crab Behavior, Marine Crab Selection, Marine Crab Compatibility, Marine Crab Systems, Marine Crab Feeding, Marine Crab Reproduction, Marine Crab Disease, Emerald Green, Mithrax/Mithraculus Crabs, Micro-Crustaceans, Amphipods, Copepods, Mysids, Hermit Crabs, Shrimps, Cleaner Shrimps, Banded Coral Shrimp, Mantis Shrimp, Anemone Eating ShrimpCrustacean Identification, Crustacean Selection, Crustacean Behavior, Crustacean Compatibility, Crustacean Systems, Crustacean Feeding, Crustacean Disease, Crustacean Reproduction,

Will this Mithrax be satisfied with just an all-algae diet? Mmmm.

Attn: Sara -Lybia tesselata Qs 09/06/08 Hi Sara (or whoever takes this), <Hi Paul :-)> Sara, you've helped me out in the past - Now, I've got (what I believe are) easier questions. I put 2 "Boxing / Pom-Pom" crabs in my tank. They've molted twice, and appear to be doing extremely well. <cool> Here's the question - What kind of anemones are on their claws? and if the crab(s) die will the anemones attach to the rocks and continue to grow? <The anemones are of the genus Bunodeopsis, please see at the way bottom of the page here: http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm I honestly don't know for certain if the anemones could/would survive without the crab. I imagine that the two could get separated (if maybe the transfer during molting does not go so well or if the crab loses a claw). The likely advantages for the anemone (of being on the crab) are 1) opportunity to get food (found by the crab) and 2)mobility (i.e. when the crab runs from a predator, it takes the anemones with it). Thus, in an aquarium, if there are no predators (and plenty of food to go around), I would guess that the anemones might have a chance of surviving without the crab.> Paul <Best, Sara M.>

Straightforward Staghorn (Crab) Question... Care of Hydroids, Bryozoans   7/26/08 Hi, <Hello there> Thanks for all the great info. I kept a Staghorn crab for about 6 months. Alas, I'm pretty sure one of the more aggressive hermits ate him (probably the dreaded electric blue). Those hermits are barbaric and constantly try to rip each other out of their shells. <What they do> The Staghorn Shell still seems very healthy. My question: Can this shell continue thriving in my tank without the crab? <Likely so... if sufficient food passes by, other conditions (light, current, water quality...) are propitious> My naive guess is that it probably can. What can I do to cultivate it and keep it healthy. regards, thanks, respect, Alan ny <Mmmm, read... on the Net, WWM re the care of the Bryozoans, Hydroids that make up the life here... e.g. http://www.liveaquaria.com/product/prod_display.cfm?c=497+501+1146&pcatid=1146 Bob Fenner>

Gaudy clown crab, care  4/15/08 Hello, Recently we have set up a coral reef aquarium and we bought a live rock with feather dusters and polyps etc on it and when we brought it home we discovered a gaudy clown crab inside of it. <Mmmm, neat animals: Platypodiella spectabilis > Now we didn't even know what it was until we found 1 website that at least had the name of it. No one knows anything about this crab I guess it is really rare. So if anyone there could please give me some information on it that would be great. Please reply back to me. at XXXX. Thank-you. <Mmm, what is known re the practical husbandry of this Xanthid can be found on the Net and WWM... like others of its family it is an opportunistic omnivore... though staying relatively small is a plus, it may well consume other sessile invertebrates. Bob Fenner>

Squat lobster and pom pom crab  2/2/08 Would you like some photos for your website? The squat lobster was labeled "Allogalathea elegans" when I bought it, but I'm skeptical of that ID. The second image is a shot of the underside of the squat lobster. <Good pix> The pom pom crab's anemones are a little droopy in this photo, but he was just out of the shipping bag. 6 months later, his anemones are gorgeous. You don't have to reply, but feel free to use the photos if you'd like. Just wanted to share. ~Felicia <Again, thank you for your efforts. BobF> Felicia, might I ask... are you a content provider in our interest? You seem to be more than a casual hobbyist... Are you interested in writing articles, selling image work in this field? Bob Fenner.

Devious Decapod    4/23/07 Hi, We have a 60 gallon tank with a variety of fish and 2 hermit crabs. The tank is doing great. My husband was doing our 10% water change and after he was done he saw something strange. He noticed what looked like a crab without a shell, so he checked on the 2 shells and both were occupied by their crabs. We decided that the 2 crabs we had, had mated so we ran to the pet store and bought some shells, however this crab is quite large to be a baby, and we have never seen it before today. I was wondering if you could shed some light on how this crab could have survived with out a shell and why we haven't seen it before today. Thanks Amanda <Mmm, likely is one that had just molted... perhaps its cast off exoskeleton is still about in your system... or it may have consumed it... to reincorporate the materials in the new outer casing... In the meantime... it's been hiding amongst your rock. Bob Fenner>

Decorator crab... something growing on it... no pic... Uhhh?  3/23/07 I have read up about as much as my brain can absorb, <Mmm, may I be excused, my brain is full?> but I have something on the back of my decorator crab, other than the many things that looks like he put on its back purposely and can not identify. It has spread from maybe a small percentage of the crab's body to about a third over a period of 5 to 6 weeks. <A fast grower!> It is clear to white in color with very small specks of bright orange. <Hmm, maybe a sponge?> I don't know if it is a disease or maybe even a flatworm. <Unlikely, I think.> It doesn't seem to  bother the crab, but it is getting closer to the crab's eyes and  mouth. <Hopefully, the crab will be able to prevent this from being a problem.> Any info would very helpful. <Can't really tell you much without a photo.> Sorry I couldn't send an image, if I can find a camera with close enough lenses I will send you a pic.   <Check to see if your camera has a macro setting, looks like a small flower, will allow you to take close ups.> Thanks, <Welcome -Mich> Jeremy

Crabbing, tossing legs  - 4/11/2006 Hi,   My name is Peggy, and I have to ask, this has been on my mind for a very long time.      years back i was watching something on TV about people crab fishing, if i remember right, they had said something about a crab that when they caught them they needed to throw a leg back in to grow. I'm I crazy or is there such a thing.         Hope you can help                                      Peggy Brennan <Mmm, actually... they likely kept a leg/claw and tossed the rest of the crab back... so that it would regenerate this missing limb next molt, and still have one left to defend itself and feed. Bob Fenner>

Halloween Crabs, Google on WWM  02-05-06       Hi there ;) . I was just wondering if you knew anything bout the Halloween Crab, i picked up 2 of them from a local pet store they had been living in for almost 3 weeks, hoping to give then at least a fighting chance seeing the personnel at the store knew almost nothing bout how to care for them.  I've been looking all over the web to find something about there care but not much is to be found.  Ant info you may provide would be very much appreciated if only a link to a site or a good book on care for the Halloween crab or another closely related breed. I'm sorry to just randomly Email you sir, just at my wits end is all                                                                   Jason Young <Sure... using the proscribed method: http://www.google.com/custom?q=halloween+crabs&sitesearch=wetwebmedia.com Bob Fenner>

Here's her crab, missing one of this anemones.

Pom Pom Crab - Lybia tesselata 11/24/2005 Great site, guys.  <Thank you Steve> I've searched the site as well as the web and have been unable to find an answer to my question. What type of anemone does the Lybia tesselata crab carry?  <The Pom Pom Crab will normally arm himself with anemones of the Bunodeopsis species (Beaded Anemone). Shouldn't be too hard to find as San Diego declared them a pest as swimmers were complaining of being stung by them in Mission Bay.  They are not native to Mission Bay, just got there someway.>   <<Likely got there the same way Batiguitos Lagoon got its Caulerpa taxifolia.  MH>> My friend's crab has lost one of his.  <James (Salty Dog)> Thanks a lot. Steve Wright

Mithraculus 7/16/05 I recently got 2 emerald crabs but i know little about them i just wanted to know how big they grow and if it is possible to breed them and if so how is it done? Thanks Rob <Read here: http://www.wetwebmedia.com/mithraxfaqs.htm and on to the linked files above... learn to use the indices, search tool on WWM. Bob Fenner>

Zebra crab help Hello-- <Hi there> you guys are great!! I recently saw a zebra crab for sale at a local fish store. <Rare...> It was an awesome crab and wanted to buy it, but I didn't know anything about it so I decided not to. <Good for you> I read up on them and learned that they live in fire urchins. <Yes... if it's the species I'm thinking of, I've photographed it there: http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm > I have never seen them for sale again (LFS or internet). I was wondering if you knew anything about them? are they rarely collected? Able to be kept? where to get them? etc. Thanks for the help! --josh <I know nothing re Zebrida practical husbandry... have never seen the species in captivity. Perhaps a search with the scientific name on Google Scholar... or a large public library. Bob Fenner> 

- Crab & Clicking - I have a 75 gallon reef tank with rock that was previously in my other two tanks that was moved over. The only things that have been added recently have been corals that are either on tiny rocks, or no rocks at all. The problem is that we have a mystery crab. This thing is huge to have never seen before. I do night patrol on a regular basis with a flashlight and have never come across it before. It is a "true crab" with large fat claws and is rusty red color and white splotches. It's about two inches across.  <Sounds like perhaps a shame-faced crab.>  It seems that it is eating my snails on a regular basis. The bottoms of the snail shells are removed, cut out, to see the spiral inside. There are several like this that have appeared recently. For the last four months or so, we have heard a clicking pretty regularly from the left side of our tank. This is where this crab has been living. I know your answer to the clicking is going to be a pistol shrimp, but no sign of that either.  <Pistol shrimp are pretty secretive.>  One of my emerald crabs also had three legs removed last week. Whatever this crab is, it's getting along ok with my coral banded shrimp. They seem to be living in the same vicinity. Any clues or thoughts you may have would be helpful and how do I get it out of my tank?  <I'd try and trap the crab... it's not going to do you any favors by staying in the tank. Check with your LFS to see if they have a trap they can rent you. Use your night prowling time to bait the trap with something meaty and bag the crab.> Thanks, Jennifer  <Cheers, J -- > 

Female Blue Crab <Julie> I have a female blue crab and for some reason it lost both it's pincers why did that happen is she sick... what's going on... will she be ok <The next time the crab molts it should have one new claw for sure and possibly two.  If not, the following molt will produce the other one. James (Salty Dog)> Emerald crab Hi, I had a question for you guys about emerald crabs. I never bought any, but one day I found one of them while I was feeding my two clownfish. I'm guessing they came with the live rock. Later on I found a dead one, but still saw at least three live ones. So I start looking around in my tank and I see lots of these little eggs (actually they are mainly surrounding one chunk of rock). I come to the conclusion that they are breeding. I have a small 12 gallon aquarium with 2 clowns, 6 snails, 6 hermit crabs, a fan worm, and x emerald crabs. Is this going to be a problem? <Hello, I would say that you can't be sure that it is the emerald crabs that are breeding.  It could be anything else in your tank. I think further investigation is needed.  If it is the emerald crabs that are indeed breeding that would be a good thing.  They like bubble algae and will help keep the tank clean.  good luck MikeB>

Pom Crab- A Pom Pom with One Arm? Dear crew of WWM,     I would like to thank you again for helping me out with my lighting question I had earlier, but I had bought 2 Pom Pom crabs and they are really fun to find when I get home.  Well, any ways, my question is that will crabs regenerate their legs if they are bitten off, and if they do how long do would you say it will take? <Hi, Ryan with you.  It depends on the frequency of molting- Regular water changes will help to keep this process regular.  They almost always grow back!> Thanks again    -Randy

Stone crab claws? is this the species (or one of) that is used as stone crab claws?  Cancer antennarius and if so do you know the reproduction cycle of this species or where I can look to find it? thanks! Ryan <Cancer genus crabs are used at times (U.S. west coast) as "claw only" food organisms, though Menippe adina, Menippe mercenaria of the southeastern seaboard are the principal commercial species. You can find a good deal of information re all these using the search engine/directories on the Net using these scientific names and the key terms reproduction, husbandry... Bob Fenner>

Shamefaced Crabs Hey, greetings from Brandon,<Hi, Mike D here and greetings from Clearwater!> Noticed you had one of these awesome crabs too http://wetwebfotos.com/usermedia/high/1/5051_23.jpg I managed to pick mine up off of the LFS off of Armenia in Tampa.<I get the best prices at bait shops, where they come in with the live shrimp, as they are often free> Unfortunately I have yet to find any information at all. As of right now I target feed him silversides, and he also gets some bits of formula one or squid that I drop in there. Its been working for 5 months or so,  any suggestions on what else to feed/not to feed him? to ensure proper nutrition.<Sure, that's an easy one. These are specialized predators that feed on marine snails and clams, thus any of the above would be greatly appreciated> Also, when I got this guy (for very cheap might I add) he was pretty damaged, missing one of his rear legs, a few of his legs were missing the last appendage broken off at the joint, and some amount of damage done to his carapace on his lower back. Nothing too serious as he's still alive and well, but I'd assume all this would be healed after a molt, which has not happened yet, and he's still in the same state as when I bought him. which leads me to my question,  how often do they molt?(6 months and counting so far) and would there be anyway to encourage a molt to occur?<Maybe and maybe not. These appear to have a maximum size, at which time they stop molting. I've found them heavily encrusted with LARGE barnacles in the wild, indicating that they go for extremely long periods in the same "skin". I've also had pairs where the female was holding bright orange eggs every 90 days or so> Finally, this crab is rather reclusive so I only feed/see him every 3rd 4th day or night<Also very common. In the wild they spend the entire day completely buried in the sand, only emerging at night to forage.>, he readily accepts any food I stick in front of his face. Any suggestions/information you could provide on this guy would be most appreciated.<From what you've told me, just adding some shellfish to his diet would be all that you could probably do. With those huge claws, it's amazing that they are almost completely fish safe (except for the dumb one that tries to burrow underneath the pretty rock, anyway!> Jared

Crab Legs?  Not This Crab.... - 03/12/2004 Hey friends I was wondering if you can give me some info on my blue crab I just picked up; Well I was talking with some of my friends at my local fish store, and I noticed one of them about feed the trigger. I saw it was a blue crab, and told him to save his life so I could take him home. <Mmmm, crab cakes....  Just kiddin'.  I have a soft spot for weird inverts, myself.> He's about 2-3 inches now, so I have him in a 20 long with live sand, and the whole deal (protein skimmer, etc...); <Nifty!  His own little paradise.> I was wondering what salinity rate would be good for him, because I know I've seen them in brackish before? <Mm.  Very good question.  The link I'm about to give you in in German, but you can use Google's language tools to translate (somewhat), and hopefully you can glean what salinity would be ideal for him, or at least ID the little bugger.  From there, I'm not sure what I can tell you....  Ask the fish store whether they were keeping him in fresh or salt water, look at the health of any others they have in stock and compare their health/activity level to yours, implement any changes in salinity SLOWLY, and observe carefully.  If dropping the salinity a bit makes him seem more active, that would be a good indicator that something's going right.  Try to identify him, and from there you can determine whether he needs an area to get out of the water or not.  Also do keep in mind that crabs are not wholly fish safe, and some are outright terrors to any fish (a real switch from almost being on the menu, eh?).> Also how long will he maybe live for? <Another toughie.  I would think that a couple years is likely, perhaps more.  Crabs and shrimp usually aren't as long lived as our finny friends, but should still do well with the proper care.  Wishing you and your crab well,  -Sabrina>

The Crab In The Rock... Scott <Hey there!> How are you? <Doin' great!> I got a small crab with my live rock. <Ahh...a "hitchhiker"!> I have not seen this bugger in about a week so ain't sure if he is dead or alive? <Hmm...> Do you think a little crab will be a problem in my tank when I introduce my fish or should I not worry too much? <I wouldn't be overly concerned. Any crab that came in on live rock and endured what it did is probably still alive! Give him time and he may reappear> My concern is that I hope he ain't dead in there? If he is alive then he is probably only coming out when the lights are out? What do u think? Regards, Ziad Limbada <Well, Ziad- I wouldn't be too concerned about the crab. As I hinted above, he's probably a pretty tough guy. On the other hand, if he did die, it's during the cycling process of your tank, so the animals' decomposition will just contribute to the nutrient load being processed by the live rock. Don't want to sound too cold here, but it is a potential risk for the crab. However, nothing is ever wasted...Nature makes use of everything...Good luck! Regards, Scott F.>

Crab in my reef 12/4/03 Hello Anthony! <cheers, my friend> I watched my reef and I realized (to my relief) that the creature I saw the other day in a dark hole in the life rock was not a mantis shrimp but a crab! It arrived as a hitchhiker on the life rock and has been hiding for 3 months! Anyway, I read all about crabs in your book "reef invertebrates" and concluded that I should trap it and take it out of my reef, as I can not identify it and there are practically no crabs that are reef-safe. <quite correct> Next question is about amphipods (or copepods, I am not sure). <the former look like arched back shrimp/prawn... the latter look like dots/fleas> There are hundreds of them on the LR and on the grass of my tank. Some are very small and some have grown bigger, as there is no fish to eat them (the clown is swimming at one corner near the surface of the tank and has not yet moved to other places of the reef). Now I am thinking of culturing the amphipods in my sump, before I buy my next fish, which might start eating them (a  Neon Goby, Gobiosoma Oceanops). What it the best way of transferring them in my sump? <just moving a little bit of dense algae or live rock will do the trick> I am thinking of moving a couple of LR that have Dictyota, Halimeda and Padina to the sump, so the amphipods on them will be transferred to the sump, too.  Is it a good idea? <yes> I have not a refugium (lack of space), so I would like to do as much as possible in my sump. <understood> Moving some LR with macroalgae on it is my first thought. Second would be a deep sand bed in the second part of the sump, which would be a problem, because: 1. There is an EHEIM return pump sitting on the glass of this part of the sump and 2. The DSB would raise the bottom by 10cm, which will make  me a slave to evaporation (will decrease my autonomy). Right now I have an evaporation of 3 liters per day and an autonomy of 7 days. If I make a DSB my autonomy will drop to 4 days. Last question for today: when I bought the Clown fish (see attached picture) I thought is was a juvenile Ocellaris, Now I am not certain any more, as it has begun to get darker close to the strip on its head and to the white spots on its back. Can you identify it please? Thanks a lot, Thanassis <clearly looks like A. ocellaris to me my friend. Best regards, Anthony>

Too LITTLE Algae?? II >Thanks Marina ... >>You're welcome. >I do intend to setup a refugium but in the meantime I will force feed greenery to Dr. Blenny and the Sally Lightfoots, until or if they are removed. >>That is the best option.  Do I make you Nori, baby?? >Another brilliant option that just occurred to me is to quit cleaning the back blue acrylic panel of algae, and let it build up and grow food for these guys. >>Simple and brilliant.  Yep. >Great .... SLC >>Yes.  Marina

Emerald Crab >I noticed a few weeks ago (~5) that my emerald crab's pinchers were missing. It seems to have lost them during one of its molts. My Sally lightfoot  crab didn't lose it and it molts about 2-3 times a month.   >>You have a mix of two different crabs, both known to become aggressive, are you certain they were lost *because* of the molt?  It could very well be that the Sally Lightfoot (btw, there are at least two, if not three, other species of crab called "Sally Lightfoot"--ALL aggressive) managed to catch the emerald at its most vulnerable.  With such a mix this must be expected. >It is still eating. It has learned to use it legs to get food. Will my emerald crab's pinchers ever grow back? >>Yes. >All the water parameters are zero and I add iodine to help with molting. >>All parameters, even pH, temperature?  ;) >Also what would a likely cause be for the disappearance of my peppermint shrimps? I had 3 but they slowly disappear. >>Quite easily one of these crabs, or you could even have an unknown (and most unwelcome) guest in the form of a mantis shrimp.  If you ever hear odd clicking noises from the tank (especially at night), you may have a mantis.  These animals can decimate a tank. >I have 4 mid-sized pieces of live rock, 2 pink skunk clowns, 1 humbug damsel, and 1 Nemo. Any info would be greatly appreciated. >>There you have it, you have an aggressive (far too aggressive for peppermints) mix of inverts going on there, in my honest opinion.  Marina Thanks

- Spooky Stuff - Dear Bob, Hi, its me Jorell and sorry to be bothering you again.  I have a bit of a crisis and need some urgent help. There is some kind or lurking predator in my tank that I have never seen, and lives in the mass of live rock.  About a week ago I had added a harlequin shrimp to the tank and a starfish for food, the Harlequin promptly located the starfish and got to business, it was having a bit of a problem turning it over and was riding the starfish, after a while the starfish want into the live rock at the back and was lost for a while, when it reemerged an hour or so later there was no Harlequin... I waited for about 3 days and still no sign of the shrimp something got it.. <Once harlequin shrimp have their prey, they often 'vanish' for weeks. You may yet see this shrimp again unless there really aren't that many places to hide.> About 3 days ago I added some leather corrals to the tank and this morning one of them is has one end eater with a chunk in the stem taken off (cookie cutter style). I believe this something is some kind of crab, I know I have two crabs in the tank one a very small 1/2 cm totally white Crab that I have not been able to identify and the other one is a purple crab about 1/2 inch across that I do not know.  I have had these crabs for years and they never molested any corals. <And even then... soft corals don't usually make it into crab fare... would look for other causes of this problem.> I am quite certain that these two guys are clean there must be another crab that I have never seen with nocturnal habits, over the last 3 - 4 days I have been visiting the tank 2 -3 nightly turning on the room lights so see if I can find it to no avail. <Consider setting a trap.> About a month ago I added a Purple tang to the tank that I believe was cyanide caught and died in about 2 days, the funny thing was when I found it 1/3 of it was eaten in a matter of minutes. <Now this IS something I would blame on crabs.> I have not added any new live to the tank for over 2 years in fact got rid of some about a year ago when I moved. Is there any way that I can trap this critter, need help urgent. <There are several commercial and DIY traps that are available - you can usually bait them with meaty sea food.> Kind Regards, Jorell <Cheers, J -- >

Crabs! >I started a reef tank about a month ago, 55 gallon. I have been adding live rock.. now up to 48lbs to get the tank cycled, and because I want to have a reef/coral tank with less emphasis on fish than some. I have a question because in 2 purchases of rock, I have apparently obtained 3 crabs. >>Not at all unusual, and it's one of my best arguments for quarantining ALL specimens that go into the display, and curing/quarantining live rock BEFORE it goes into the display. >One resembles an emerald crab but is more gray than green, one is brown with relatively small pinchers and furry legs, and a third seems like it has small spikes all over its legs and has much larger pinchers than the other two. I witnessed the small brown crab eating things off the rock tonight.. it just seemed to be randomly picking at it, but several times it had some hair algae and nibbled on it some. >>This sounds like a good thing.  Observe. >I have a very small brain coral that came with one of the rocks.. >>COOL!!!  Sounds like excellent live rock.  Please share where purchased for our other readers. >...but I would like to add more corals and inverts in the future, so my question is whether you think it would be best to remove these crabs? >>Might be, but I would watch them first.  The one with the large pincers would be the first I'd go after, and crabs are easily caught with the "jar stuck in the sand" method.  Simply bait it, and leave it at a sufficiently steep angle that the crab cannot get back out (remember, it has to be large enough that it can't get back out). >My LFS told me that there are only a couple varieties of crabs that would be desirable, and upon reading the marine crabs FAQ's it appears that even they can be trouble. >>True. >I think in time I might be able to trap these crabs out.. but am not excited about that. What would your advice be? Ever grateful!  John >>I would go ahead and trap the ones I can trap, then they can be popped in the 'fuge or other for observation.  Marina

Shrimp/Crab Molting - 8/23/03 Hello Crew... <howdy> Great resource you have here.   <thanks kindly> I have a 2 mo. old 37 gallon marine aquarium with 4 hermit crabs (2 blue legged, 2 red) and a cleaner shrimp, plus a maroon clown, Fiji damsel and a yellow clown goby.  20+ lbs live rock etc...2 quick molting questions... 1.  Do the hermit crabs molt? <yes... all crustaceans... shrimp, crab, lobsters, etc> 2.  After my cleaner shrimp molts (and perhaps the crabs), should I remove the shed skin/shell from the tank, or does it serve a better purpose being left alone? <the latter indeed... something (perhaps the owner) will eat it for its rich chitinous nature> Thanks for the input! Bob <best regards, Anthony>

Strange Hat Hello Crew, <Howdy Paul> I hope the picture comes through clear enough.  I adjusted the contrast and brightness a bit on the image, didn't come out that great.  It was night time, so taking a picture in the dark is a bit tough.  Anyways, on this rock that has a few zoo polyps ( dark spots ), there is a crab.  My question: is that a sponge on his head? <Actually, more on this back (carapace)> Also, interesting worm in the background a well, maybe a peanut worm? <Looks like it to me as well. Bob Fenner>
Thanks, Paul

Showing Crabs The Exit! I have a 75 gallon reef tank with about 150 pounds of rock. I have about a 20 gal sump with the cs6-1 Euro reef skimmer. <A great skimmer!> A Dolphin AS2100 pump keeps the water moving very fast but I do keep it dialed down some. I also have 4 powerheads run by the Wavemaster pro. I also have a 18" CPR refugium on the back of the tank.  Is this a good set up or is this to much water flow? <Well, "too much" is a relative term...All depends on the animals that you intend to keep!> It is lit with the JBJ Formosa 260 watt compact lights.  The tank has been set up about 6 months.  I have had a few fish loss' along the way, but seems to be stable now.  I have 2 Percula clowns 2 cleaner shrimp 1 emerald crab.  I have about 40 small crabs. I am not sure which kind and 20 snails or so; an assortment of different types. My question is, I have noticed a couple of crabs eating the stems on my hammerhead coral to the point that it does not have much left before it falls apart or dies.  How do I stop this, and how do I keep this from happening??  Thank you for any information you can give me based on the information I have given you. Chris Atlanta, GA <Well, Chris- that's a tough one. Unfortunately, some predatory crabs and shrimp will simply not stop feasting on corals. There is generally not much you can do, other than removing either the corals or the crab from the tank...A definite trade-off! If it were me, I'd give the crabs the heave-ho! Good luck! Regards, Scott F>

What crab be thee? >Hi :o) >>Greetings, Wendy (love your addy, btw).  Marina here. >We have just bought 2 Tricolor crabs (not sure if they have another name).   I've tried searching on the Internet for some information on them but to no avail, perhaps I just don't have the navigational skills, but I did come across your website and although I cannot find a particular mention to them.   Could you possibly give me any information on them i.e. maintenance, feeding, etc. or point me in the right direction to any other websites? >>Well, I've Googled your information on our site, and only come up with a website on a species of hermit (saltwater/reef) crab.  I see a red "x", so if you've tried to attach a picture I'm not able to view it.  If you can try resending the pic we can give it a better go.  Any information is helpful here.  Marina

Sally lightfoot molted and is now deformed >My sally lightfoot crab was doing fine, but it molted last night.  Now he is missing two of his left legs and one of his some of his legs are deformed and bent backwards and his claws look very much smaller and deformed as well. what happened??? he was normal before. Will he grow the missing legs back, will the deformed legs 'straighten out?' >>Wow, I've never experienced this before, but I have to wonder if it could be related to insufficient (available) calcium and/or iodine levels.  At this point, I couldn't tell you whether or not the crab will re-molt to its old, healthy self.  I am unable to readily find similar stories, let alone any information that would give us an answer.  I suggest posing this question to our forums at http://www.wetwebfotos.com/talk. >Also, do decorator crabs molt? >>All crustaceans (nay, all animals possessing an exoskeleton) must molt to grow. Best of luck to you and your poor crab!  Marina

Arrow Crab Spawn Hi folks, Martin here in the UK <cheers, mate :)> great site, it has been literally a life saver for me at times, well not  me personally but for some of my reef inhabitants. <thanks kindly... it is our hope/purpose indeed> Any way I wonder if you can shed any light on the happenings in my tank, last night my arrow crab opened up the bottom half of its abdomen and spewed out what seemed like thousands of tiny white pinheads with very short wriggling tails. <yep... you might research the "zoeae larval stage of crabs" for more info/insight> the fish ate most of them, the shrimps ate more but this morning there are still about 20 or so scattered around the aquarium clinging to the algae on the side walls. Some I know disappeared into the substrate as well. <a delightful occurrence! None will survive in the display proper, but you may choose to work with the breeders in a separate aquarium> the guy at my local fish shop says he has never heard of this happening before and a brief internet search revealed little about the habits of this crab other than to say don't keep it with fish, shrimps corals or anything it can eat. <the reproductive activity is rather common... rearing the larvae successfully is what's rare (hard work indeed)> I have had it in my reef tank for some time without incident. I guess you could say watch this space, but so far so good. Any idea as to what I can do with this spawn, can I rear it, does it have to be kept separate or under special conditions or should I just let my fish eat it. cheers martin <definitely must be done in a separate vessel... do look into purchasing the book on rearing Peppermint Shrimp (Lysmata) by April Kirkendall... quite similar techniques with rearing such Decapod crustaceans (although the Lysmata are hermaphrodites). I think Midland Reefs in the UK carries this titles. You can e-mail a chap named Tim Hayes at midlandreefs@inverts.demon.co.uk kind regards, Anthony>

Mithrax Crabs    Hey fellers, <Hey Hey> I was just reading your postings on bubble algae. I have a small patch of the stuff which I vacuumed up once but it came right back. I saw your recommendation for Mithrax crabs.  Are they reef safe? <They are supposed to be, but every crab has its own personality.> Do they have a common name or are they only known as Mithrax crabs?    <Around here (Northern California) they are usually labeled Emerald or Green Crabs.> One last; could aging lights be partially responsible for this pesky stuff?  I've never had troublesome algae before. <Can happen with other types of nuisance algae, but not usually the bubble algae.  As the bulbs get older they can drift towards the warmer end of the spectrum and encourage nuisance algae.  Be sure nutrient export is good, manual removal of the algae may work best. -Gage>

- Algae, Starfish, and Crabs... - <Good morning, JasonC here...> Before I ask my questions, here's some background info... 90 Gallon Tank Canister Filter 27oc Salinity: 1.023 95lbs live rock 2" live sand (ya, I know it should be 3") <Unless you want a deep sand bed, 2" is fine - 3" can cause trouble - 4-6" is best for deep sand beds.> 2 Percula Clowns 1 Fire Goby 2 Watchmen Goby Coral Banded Shrimp White Striped Cleaner Shrimp Pistol Shrimp 1 Emerald Crab 45 Blue Legged Hermits 20 Snails 1 Black Brittle Star (5-6" in diameter tip of leg to tip of leg) Just a few questions for ya guys today...  it's been a while: 1.  I have a nice rusty looking red algae growing on everything.  Looks kind cool on the liverock, but it is also growing on some big fancy sea shells and on the hermit crab shells.  It's growing on my fake plants in the tank and on my power heads too.  I've heard that all this algae is good, but it is turning my tank red.     a)  Why is just red algae growing? <The prevailing conditions support it.>     b)  Is this ok for my tank or should I have more of a clean-up crew (crabs/snails)? <Or look to things you may be doing to encourage it - over-feeding, phosphates in source water, high nitrates, etc.>     c)  How do I limit the growth instead of it taking over my tank? <See my answer to B.> 2.  My hermit crabs keep disappearing. It seems as though I have 3 spots in my tank that are just littered with broken, cracked, vacant hermit crab shells.  I see my Pistol Shrimp pulling them into his lair from time to time. As well, I see my Mithrax picking them up and pulling them out of their shells.  Is it usual to see a huge collection of shells in various spots of my tank? <Sure, when someone is eating them...> Not sure if they are all eaten or if they have just outgrown the shells and moved into some bigger ones I provided. <Uhh... you just explained the whole thing. Someone is eating your crabs. No mystery here.> Perhaps a combination of both?  P.S.  Their shells are going all red algae covered as well. 3.    I have a very nice large black Brittle Star that stays in a little hole in my live rock.  I have only seen a few legs out of the hole in the last month.  I did notice that one day he moved to another hiding spot on the other side of the tank.  Therefore, he has moved out of the small hole once that I have noticed in a month and more or less stays there with a few legs hanging out.  My Coral Banded Shrimp tends to hangout right by his hole.     a)  Do you think my CBS may be preventing the Brittle Star from leaving? <No.>     b)  Does this sound usual?  Will my starfish starve in that little hole? <Probably not.>     c)  Anything else sound a little fishy?? <No.> Thanks for your help guys... Dave <Cheers, J -- >

Green Emerald Crab Mr. Green was eating bubble algae and green grass till he devoured it. I had 4 damsels 1 domino one white and black striped and 2 blue with yellow tails. Removed all but one yellow tailed. 2 peppermint shrimp s sifting stars are still in there. I was feeding them frozen brine but backed off on the amt. of brine (enough to feed the tang) didn't want to pollute the tank. don't know if I should continue to feed more for the crab or what meaty things to feed him or the shrimp. Will get more fish (Gobi blenny and hopefully a tang eventually but I want to go slow and add more live rock. I will do the rock first so not to stress the fish out. <You should try feeding some Mysis and some other foods and stop the brine as most is over 90% water and has little nutritional value.  Yes, you should be feeding the crab also.> I am taking my time whew patience is a virtue. next question for the duster I fed Mr. green real well and went to move the duster he is at the bottom of the tank but now I have another problem. He has seemed to attach the end of his tube to the rock. now what? Do I tug and remove it and move him or what? can anything be easy LOL? Please help thanks. < You could try to gently cut it away but it would be best to move the whole rock.  I don’t think you could just rip it off without doing some damage to the worm, as they attach themselves very well. Cody> Misty

Get Crabby!   4/9/03 Hi Bob.<I'm Phil, but I play Bob on TV.... :) > Before I go any further thanks for all your help.<It's our pleasure, for me answering questions isn't like a job.  It's almost kinda fun helping someone "setup" a tank and seeing the finished product.  Amazing...> and as you guessed it I need some more.<Let's solve the problem!> I had bubble algae which I bought a green emerald crab and he devoured it along with all my blue green algae. glass anemones which I bought peppermint shrimp and they devoured them.<Good> YEA I watch my crab and he was very gentle with my mushrooms (AST varieties) my polyps (which are splitting and reproducing I think started out with 3 now I have 7 on one rock. feather dusters not the tiny ones they are brown nestled in the rock (came as hitch hikers) he was great with all of them he would place his claw over them feel them and go on for other things. Then today I bought a beautiful large feather duster. (brown and white) the tube its in is about 1/2 in in dia and about 6 in long the tube is light tan like light mud and the end about 1 1/2 inch is almost clear. here is the problem Mr. green came popping out and clamped onto the end of the tube and started dragging it under a rock then stopped and started tearing at the tube (eating it).<Oh no!!!> Poor feather duster seems to be fine. Its head is out and seems less for wear at the moment. I finally captured Mr. green and have him in a quarantine tank. Everyone I speak to say their crab doesn't bother their feather dusters. was he really going to tear this thing apart or just eat the clear part. I hate to get rid of him he is such a help in the tank. can I cover the tube of the worm with sand or place it under a rock so he cant get to it? Will it hurt the worm to cover it to the point of 1 or 2 in below the head with sand?<My Mithrax crab doesn't touch my corals etc.  But in your case I don't know if putting the feather duster under the sand will help.  The crab might just climb on top of it.  Try placing the feather duster on another rock elsewhere in the tank.  Then add the crab back, he might not touch it this time.  What have you been feeding your crab?  Maybe he wanted some food and the feather duster was right there.> I really need advice on how to handle this situation. I also bought two Nudibranchs OK didn't read before I did this so this is what I bought a Hypselodoris bullocki and a Philinopsis gardineri now I need to feed these critters the LFS said they are like snails yea right so I now know they are not eating algae and surviving I tried to find info on feeding them and I cant find a whole lot of info on your site or another is there something I can put in there besides bristle worms soft corals or sponges to feed them? <Some Nudibranchs feed on the light.  What kinda light do you have?> thanks a million if you can get back soon I would sure love it and so would Mr. green :>)<Sorry this took so long to get back to you.  I hope this helps you and Mr. Green!> Misty<Phil>

Sally Lightfoot growth. >Hello guys, >>And gal here, Marina today. >Thank you for all your wonderful information you have available, but I could not find anything that tells me about Sally lightfoot growth.  How big to they get, and is it normal for my little guy to molt twice in 2 weeks?   >>Only if they're doing *exceptionally* well.  If yours is molting this frequently, then clearly you're doing something *very* right.  As far as how big, let's see if I can find some links for you.  Mine only got to be about 4" from tip to tip.  However, she never did molt as frequently as yours is. >He seems to be doing fine, when I can find him and is active, and eating constantly.  Bill >> http://saltaquarium.about.com/library/weekly/aa100600.htm http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabfaqs2.htm http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabfaqs.htm >>Well, Bill, in large part because there are more than one species of crab called "Sally Lightfoot", I can't tell you how big this thing will get.  I'll just warn you to watch it closely.  Marina

Le Crab Fantastique! Dear Crew: Please see the attached jpeg. I found this crab in my refugium. Can you tell what it is? Is it a problem? Thanks, Steve Allen. >>Hi Steve.  Not knowing it's size I can only venture a guess.  It appears to be quite small, and from what I can make out the pincers are small (relative to body size) as well.  Since it appears to be covered with some kind of algae or sponge (maybe even detritus) I would treat it as a small hitchhiker who will likely remain small.  At this point I would consider him a benefit, but certainly watch for nipped sessile inverts and such.  If the thing seems to grow at any appreciable rate, then I would remove him to the refugium (assuming you have one). >>Also, I know it's about impossible to make an I.D. without having a "crab bible" handy (it's why I can't make an I.D., though someone else in the crew might be able to), but I will link you to our invertebrate library at--> http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm >>Good luck!  Marina

Get Crabby!  3/15/03 Hi<Hey> I looked all over the internet to see what decorator crabs eat and am still clue less I have silversides and algae cubes and lots of algae in tank will he eat any of these?<Try reading here http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm and try entering "decorator crab" in the WWM/Google search bar.> thanks JM<Hope this helps!  Phil>

Re: Coral Banded Reef Shrimp (and Stenorhynchus) I have a 46 gallon tank, with a coral banded reef shrimp, arrow crab, three peppermint shrimp and three cleaner shrimp.  also have regal tang, two small clown fish and two small damsels.   All live in harmony, or so I thought until my Coral banded reef shrimp showed up one morning without any claws.  Is there any kind of explanation for this?  I find it truly strange that the "bully" in the tank got bullied by something else. <Not me... the most likely suspect is the Arrow Crab... as this animal gets larger, there will be other "missing parts", then whole organisms. Please see here: http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm and the Related FAQs (at top). Bob Fenner>

Any input re: the mud bed/fiddler crabs? Thanks! -Will <please read here: http://www.wetwebmedia.com/PlantedTksSubWebIndex/fwbraccrabs.htm Cody>

There Was Three... Now There Are None!  3/11/03 Hello all at the WWM,<Hey there Matt!  Phil on duty tonight!> for the last couple of weeks I've had 3 fish die in my tank. 2 Yellow Tailed Damsels and 1 Firefish. They all seem to die overnight and all are healthy right before they die. I don't know who's or what is killing them but I know I don't have any Mantis shrimp or any of that cuz I've already done fresh water dips on all my rocks and gotten all that stuff out. Plus I've already went through and inspected everything. But anyway last night my Firefish died and when I woke up I found him in the same place dead as the 2 yellow tailed damsels missing one of his eyes. This is the same spot the Arrowhead crab likes to hang out. I was wondering if the Arrowhead crab would be the thing killing my fish. I mean would be he goin after them and killing them while they rest on the bottom? I also have a Nimble Spray crab in my tank as well but he never seems to mess with nothing and actually acts like he's scared of the fish. So should I take the Arrowhead crab out? Cuz I only bought him so he would eat any small bristle worms and stuff.  Thanks for your help<I would really like to see some info on water quality...  I highly doubt the crab is the one killing the fish!  <<RMF doesn't>> I think the fish die and he brings them over to his area of the tank and "samples" them.  Please get back with me on the water levels, as I think this is the main problem.  Keep in touch! Phil>

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