FAQs about Crustacean Identification 2 Related FAQs: Crustacean Identification 1, Crustacean ID 3,   Crustacean ID 4, & Crustaceans 1, Crustaceans 2, Crustaceans 3, Crustacean Selection, Crustacean Behavior, Crustacean Compatibility, Crustacean Systems, Crustacean Feeding, Crustacean Disease, Crustacean Reproduction, Micro-Crustaceans, Amphipods, Copepods, Mysids, Hermit Crabs, Shrimps, Cleaner Shrimps, Banded Coral Shrimp, Mantis Shrimp, Anemone Eating Shrimp, Horseshoe Crabs,  Related Articles: Crustaceans,  Micro-Crustaceans, Amphipods, Copepods, Mysids, Isopods, Shrimps, Coral Banded Shrimp, Cleaner Shrimp,  P. holthuisi Pix, Mantis "Shrimp", Lobsters, Slipper Lobsters, Hermit Crabs, Squat Lobsters, Crabs, Arthropods, Pycnogonids (Sea Spiders),

Mystery Bug: Gammaridean Amphipod and Disappearing Zoanthids - 7/19/09 Hi, <Hi y'all, Lynn here today.> We're wondering if you can help identify the mystery bug in the enclosed photos. <Yep, it's a harmless Gammaridean amphipod, also known as a scud or Gammarid.> We have a 30 gallon salt water tank that is about a year old. We've been having some problems with our Zoas (they're disappearing a little at a time as if being eaten) and took them out for a Lugol's dip. This guy was one of the unfortunate victims that came out. Is this a type of copepod? <Nope. While they're both crustaceans, Gammarids are in the order Amphipoda while Copepods are in the order Copepoda. For more information on Gammarids, please see the following link: http://bb.wetwebmedia.com/viewtopic.php?f=25&t=125&p=2869&hilit=gammaridean#p2869 > Is he anything that would eat a Zoa? <I doubt that he'd eat a healthy Zoanthid, but he could potentially eat dying tissue left by a predator. Gammarids can and do however, sometimes act as Zoanthid 'irritators' due to their grazing and foraging habits. Some Zoanthids simply don't like all that contact and react by keeping their polyps closed for extended periods of time. If your Zoanthids are opening as usual, but simply disappearing, I'd look for the usual suspects: Heliacus/sundial snails, Aeolid Nudibranchs, hydroids, etc. Please see the following links for photos and more information: http://www.zoaid.com/gallery2/main.php?g2_itemId=384 http://www.zoaid.com/index.php?name=FAQ&id_cat=3#q15 http://www.wetwebmedia.com/zoanthidcompfaqs.htm I'd also recommend checking the remaining Zoanthids for any sign of small light/whitish spots. If so, it could be what some hobbyists call Zoanthid pox. Please see this link for a photo example: http://www.zoaid.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=3573 For treatment, see the first FAQ, titled 'Zoa Pox Treatment -- 05/09/09' at this link: http://www.wetwebmedia.com/furancpdfaqs.htm More info here regarding diagnosis/treatment: http://www.wetwebmedia.com/zoanthidhlthfaqs.htm > Thanks for the help, <You're very welcome and good luck!> Pegine and William <Take care, LynnZ>

Deep Water Crustacean Caught: Likely a Mantis Shrimp, yes, you can eat them 4/28/2009
Hi,
<Hi Bill>
While grouper fishing yesterday in about 70 feet of water in the Gulf of Mexico 20 miles off Venice, Florida, I caught an unknown crustacean.
<OK>
It was about 12 inches long, and had exoskeleton like the tail of a lobster, yet almost clear, and uniform width of about 2.5 inches from front to back.
It had two arms in the front, long and doubled back like a praying mantis arms. These "arms" were holding onto my squirrel fish cut bait. At the back it had two or more sets of scissor pincers.
<Heheh. Lucky it was interested in your bait and didn't try to sample your hand.>
Do you know what this was?
<Likely a Mantis Shrimp Look here and see if anything looks familiar.
http://www.wetwebmedia.com/marine/inverts/arthropoda/stomatopods/mantisshrimp.htm >
Is it rare?
<Not in the slightest - I'm betting most that keep marine tanks with they were much rarer than what they are.>
Is it eatable?
<Actually, they are - do a Google search on the web - there are several recipes for them.>
Thanks for your help.
<My pleasure>
Bill
<Mike>

ID help please, Mantis 4/11/09 I have been searching for an identification on this guy for quite a while and was hoping you could help. <Will try.> I first noticed him in my tank ~ 6 months ago and have done some searching for an ID from time to time since I haven't been too worried about him. In the last two months I have lost 2 bottom dwelling fish and am a little concerned that he may be the culprit. <A possibility.> He is yellowish green in color and is about 2 inches long and his tail looks somewhat like a shrimp. <Not a true shrimp, but commonly referred to as a Mantis Shrimp, of the order Stomatopoda. Judging by the picture could very well be a "spearer" as opposed to a "smasher" and a threat to fish. Nice looking specimen here.> My only guess is that he is some kind of isopod. He is very illusive and while not very good the attached pictures are the best I have been able to get since I noticed him. <They are quite secretive and clever.> He is kind of neat and I am hoping that he is not too destructive as my 2 year old daughter is very fond of her "Creepy Eyes" Thank You -Josh <I would remove this, could be a threat to your other livestock. There are several commercial traps that are fairly effective in catching these clever animals. However they are quite attractive and popular to keep in their own dedicated tanks. Perhaps a small tank just for him would be an option here for your daughter, just make sure little fingers are kept outside the tank, these crustaceans are often refer to as "thumb splitters" for a reason. For more check out here http://www.wetwebmedia.com/marine/inverts/arthropoda/stomatopods/mantisshrimp.htm and the links in the bibliography.> <Chris>

Mantis Shrimp Reproducing in My Tank? Nope, Gammaridean Amphipods - 4/6/09 <Hi Samantha, Lynn here this evening> I bought about 160lbs of live rock from the Gulf of Mexico about 3 months ago. I have already caught 3 (what I think are adult) mantis shrimp. <Yikes> There are many more still in the tank, at least 5 more, that I have seen. The tank is 300 gal plus a large sump. <Nice> This afternoon I found a little shrimp on the wall amongst all the hair algae and other debris. I only wipe the front for a more natural tank. There is what looks like an algae cocoon but open on one end with a baby mantis shrimp in it. He wiggles and moves up and down but looks like a larva. I am attaching a couple pictures to hopefully figure out what the heck is going on I have had some fish and shrimp come up missing, and I think it might be possible because everything else is growing in my tank... why not a baby mantis shrimp... please help. <Sure thing. The good news is that what you're seeing is a harmless, beneficial, and extremely common little hitchhiker called a Gammaridean amphipod. We have a lot of information on them here at WWM: http://www.wetwebmedia.com/amphipodfaqs.htm (also see related links at the top of the page), http://bb.wetwebmedia.com/viewtopic.php?f=25&t=125 > Thank you Samantha <You're very welcome. Take care, LynnZ>

Identifying a Mystery Invert 12/09/08 Hi gang, <Hi Robin, Mich here.> I have a 120g reef tank with a 30g sump. Following a tank crash after moving this past fall I've slowly been restocking my corals. <Sorry for your loss... even more sorry for the corals.> A couple of weeks ago I bought a small Zoanthid colony. <A very pretty colony!> The other day while feeding the tank I noticed a tiny new resident who apparently hitched in on the rock the Zoas came with. <Cool!> I've looked all over your most awesome web site, but have been unable to find anything that helps me identify my new critter. <Hopefully I can help.> He's very shy <Apparently!> and this was the best photo I could get of him. <Heehee! Are you sure he's in the photo?> If you look in the center of the image you'll see a dark patch with what appear to be 2 little black balls. <I do see.> Those are his eyes and just about all I ever see of him. <There's nobody living here in this rock... now don't go looking here... cause there's nobody here...> I once saw him venture part way out of his hole during the day and he looked to be shaped like some sort of shrimp or lobster. <I believe you have a crab.> His eyes look like that of a Mantis Shrimp, <I'm in agreement with you... the eyes do remind me of a Mantis shrimp, but I don't think that's what you have.> but I did not see any claws. Rather, to catch his food he holds out 2 small, flat fan shaped appendages. <This is the key information.> He sits just inside the edge of his hole with his fans outside, waits for food to drift close by then snaps the little fans together like he's clapping to grab his morsel. <Yup.> Sometimes he lunges to grab the food between his fans. I've seen him take plankton and this morning saw him "capture" a small pellet of fish food. <Sounds like a Porcelain Crab (Petrolisthes spp.) to me. They generally have large claws but they have a defense mechanism that allows them to actually drop their claws, which continue to move, when threatened. Presumably this acts as a distraction to the perceived threat allowing the crab to escape hopefully unscathed. They are generally suspension feeders or scavengers and will eat meaty aquarium foods. Shimek reports them to be reef compatible. More here: http://www.wetwebmedia.com/galatheids.htm http://www.wetwebmedia.com/squatlobfaqs.htm > I've never seen him come out of his hole completely and he appears to have more courage under cover of darkness. <Yes, are generally reclusive and nocturnal.> What is this new little roommate of mine? <I think you have a nice little or perhaps not so little addition!> Thanks, <Welcome!> Robin <Mich>

Def. a crustacean, eyes like a Stomatopod... RMF

Gobies, Firefish, Jawfish- And a Familiar Ticking Sound! (Possible Mantis Shrimp?)   5/2/08 Good morning fishy folks... <Hey there! Scott F. in today!> It's been months since I last wrote you... so things have been running pretty smoothly I must say. Just wanted to pick your brains about two things... <Pick away!> I've had a pistol shrimp for a few years before finally giving it away due to the increasing hermit crab grave yard in my tank, so I am fairly familiar with Pistol Shrimps. Last November, within about a month of adding new liverock... I heard and quickly spotted a mantis shrimp and was able to catch him and trade him off for a feather duster at my retailer. <Hmm..I wonder who made out better on that trade?> Now, I am hearing a somewhat familiar sound coming from my tank and I haven't added liverock since October last year. I have 4 hermit crabs, a peppermint cleaner shrimp, a large coral banded shrimp, and some sort of 'rogue' large black Mithrax crab. The liverock that was added in October seemed to be crawling with sandy brown-legged black-shelled crabs similar to that of a Mithrax crab. Every so often they'd turn up dead washed out to the front of the tank by my Wavebox. To my knowledge, I only have this one single LARGE (about the size of a Canadian $1 coin) crab. Anyhow, last night... the two shrimps and this crab were in the same corner of the tank in close quarters. I heard 3 large pops (similar to that of a Pistol or Mantis Shrimp) and the two shrimp and the crab scattered. <They must know something you don't, huh?> My question is... can a crab make this noise?? I am thinking not. I know the CBS and Cleaner certainly can't. I'm worried that I've potentially had another Mantis Shrimp unknowingly for months. I do spend quite a bit of time in my aquarium room and I'm surprised this would be the first I have heard it, if that is in fact what it was. <I suppose that it's not impossible for a crab to make this sort of noise, but I'm with you- I'm leaning towards a Pistol Shrimp or Mantis Shrimp. A nocturnal investigation into this is definitely in the future for you!> With respect to this large 'unwanted' crab... it seems to be content picking at the encrusting algae on the rocks, it leaves my mushroom and polyp corals alone, seems to not be bothering my much smaller hermit crabs or my fish (Two Percula Clowns, Kole Tang, Fairy Wrasse, Two Yellow-Headed Jawfish, yellow-tailed blue damsel. I do like this crab, but his size and the fact that I can't properly identify him makes me nervous that he is in my tank. He looks big enough that he could do serious damage to any of my Jawfish should he be interested. <My personal philosophy with potentially problematic inhabitants is "When in doubt- take it out!" Trust your gut instincts on this and don't wait for problems!> Of note, this is a 90gallon tank with 90lbs liverock, and a 4" sandbed... and the Wavebox is an awesome addition! <A fabulous piece of equipment!> I also have a 24gallon Nano-tank. I've been housing my rather large Yellow Watchman Goby in this tank solo. Recently I added more cured liverock bringing my total to about 30lbs in this tank. I also added a Blenny (Bicolor ?). The two have been doing well together over the past few months. The tank seemed to be thriving and I added some polyps and some Hammer corals that also seem to be doing rather well. About two weeks ago, I figured it was time to add the final residents, 4 small hermit crabs and two Firefish. I did have a concern that the Watchman Goby might be a threat to the Firefish, but the retailer whom I trust figured I'd have good odds with this combination. <I'd generally be quite comfortable with this combination, but I cannot say that keeping a "non-mated" pair of Firefish is always easy. It seems that one almost always takes out the other in a relatively short time.> I did not quarantine the Firefish as this 24gallon tank is really my 'extra' tank and gobies fair rather well to common disease and illnesses that may be presented by new additions. As well, I figured after reading... that the Firefish also were pretty resistant and I had been checking these Firefish out for most of two weeks at my retailers. <I have to voice my gentle disagreement with this theory. Just because a fish tends to be "disease resistant" is not a valid reason to skip quarantine. The fish could be a carrier for disease, or may simply contract a disease (despite it's "reputation") for any number of reasons. Why risk it? A simple quarantine aquarium is such an inexpensive investment and can provide numerous long-term benefits. At the very least, a quarantine aquarium gives livestock a chance to acclimate, adjust, and "rest" after the rigors of capture, transport, and handling between the reef and the local fish store. Please do consider embracing the practice of quarantine in the future! OK- off my soapbox now!> Within 48hrs of introducing the pair of Firefish, I was missing one and my watchman goby was acting strange. It kept taking mouthfuls of sand, moving it's mouth around, and then spitting the sand out. <Possibly, he/she was simply demonstrating territoriality...hard to say what this behavior meant.> Luckily, the goby was doing this right in front of the glass and I am about 90% certain I could see the missing Firefish in the goby's mouth. <Hmm...I'd be surprised if the fish was eaten by the goby. Rather, I think that the goby may have been attempting to scavenge.> The other Firefish was hanging out near the surface when the lights were on and was hiding at night. <Not an unusual behavior. These fish like to retreat to safe areas at night, or whenever threatened.> 5 days later, the remaining Firefish is laying dead on the sand bottom untouched. <Sorry to hear that.> I figured if the watchman goby was eating the carcass of the initial Firefish.... We wouldn't he feed on the 2nd one. Would it seem more likely that the goby caught the first Firefish? Anything seem strange here? This Watchman Goby is about 4" and thick and certainly had the capability to swallow these guys whole. <I'm sure that he is capable, and it's not an impossibility, but I would be a bit surprised to see this happen.> Ok, I lied... I have a 3rd question. <Two minutes in the penalty box for you!> My two Jawfish of medium and large size upon first introduction to my 90gallon tank last October shared accommodations for about a week and then moved to opposite sides of the tank. Just in the past two weeks, they have shared a very small hole and it seems almost like the smaller one is on the lookout catching food items. On occasion I see the larger one come out to feed. I coulda sworn I saw the smaller Jawfish actually catching food items and spitting it into the mouth of the larger Jawfish on at least two occasions. They seem to have a pretty cozy hole with just a single entrance that they close up at night. In your opinion, is this mating / nesting behaviour? Should I possibly expect to see little Jawfishes if I have the chance to witness before the damsel or fairy wrasse move in to make a meal? David Brynlund <Good question, David. These fishes do establish social hierarchies, so it is possible that they are simply settling in. On the other hand, if they are interacting in such a close way, I would not be surprised if you see some sort of spawning event in the future. Best of luck to you! Regards, Scott F.>

Gobies, Firefish, Jawfish- And Familiar Ticking Sound (Cont'd.) 5/2/08 I totally agree with you on the quarantine tank... But this is, sort of my quarantine tank. I had no place to put my goby and I've had him for years... So I dressed the tank up with a sand bottom and liverock. My other tanks were fully stocked. Wife kept complaining that the goby looks so sad and needs some friends. I think of this tank as not a main display... But a extra habitat? I mean, it's still very easy to dismantle should the need arise. <Ok, let's call it a "semi-permanent feature". A true quarantine aquarium is bare bottomed, sparsely decorated, and broken down after use. If the fishes in this aquarium are destined to another aquarium after some period of time, it may qualify to some extent.> Ok, so first thing this morning I do my usual checking of tanks in the dark... With the flashlight. For my reef tank, I usually count my fish that tend to hide... Check out my shrimps that are always out and about in the dark... And I check for the whereabouts of the rogue black crab. However, this morning I see something tiny (almost un-noticeable... Like maybe 1mm) wiggling about... Is it some sort of small crustacean/brine shrimpy type thing? No, the wiggling thing seems to be attached to an arm and I notice orange and green and a body ducking quickly into one of the holes of the liverock. I scanned the rock with the flashlight for most of 20minutes noticing that there was something in there hiding from me. I didn't get a great look... But I trust my eyes and instincts that my 'better' look near the end would identify this as a fairly small 2cm mantis shrimp. Could be wrong, but I think it's there. I quickly removed the eggcrating top and pulled this large porous rock out immediately and placed in a bucket. I carefully poured cold fresh water into some of the pockets avoiding my polyp corals in attempt to flush the shrimp out into the bucket. Instead, I did get a small beige flat shelled crab (not anything like a Mithrax... Some sort of sand crab?). I'm pretty sure that's NOT what I saw originally and I do hope that I managed to lift the rock with the apparent mantis shrimp still inside. Finally, I was running late for work... I placed this rock in my 20g quarantine tank. DOH! You busted me... Yes I do have an additional quarantine tank... Should my polyp corals be ok in a quarantine tank with only 60watts of lighting on it... Even if it is for a day or two? I hope to be able to spend more time and flush out this mantis. Any suggestions? David Brynlund <Well, David- I think that you might be on to something here! As another alternative, I'd consider removing ALL the rock and possibly desiccating it for some period of time. Yes, there will be "collateral damage" to the life forms on the rock, but the Mantis (if present) will be history. You would, of course, remove any corals on the rock first. If you opt to keep the corals in the QT, you can compensate for the lower light by increasing feedings. Best of luck! Regards, Scott F.>

Possible mantis shrimp  6/3/07 Hello crew, I want to start off first saying how wonderful your site is. It has helped me, and I'm sure other aquarists plenty. I have a question though. I have a 75 gallon aquarium with a 29 gallon sump. It's got about 85 pounds of live rock in it that I got from someone who was leaving the hobby. <Fortuitous> I waited until the tank cycled and then purchased a few snails and hermits. All 3 of the black margarita snails have died. One of the two turbo snails has also died, and a hermit now has it's shell. I didn't think much of this because I didn't have any extra shells in the tank for the hermits. The empty snail shells are just empty, they have no holes and are not broken at all. About two weeks ago I purchased a lawnmower blenny that was about 3 inches long. I drip acclimated him for about an hour and put him in the display. I know I need to quarantine, and do plan to in the future. He was a little stressed and found a place to chill out until the lights went off. Once the lights went off he moved around a little, but not too much. I woke up the next morning and couldn't find the new blenny. I looked in the tank, around the tank, in the sump, in the overflows. I just couldn't find him. I continued the search for a few days, and never found him. I never saw a spike in any of my ammonia, nitrates, or nitrites. I have absolutely no idea what happened to him. <Perhaps it "jumped out"?> About two nights after the blenny went missing I heard two distinct sets of popping sounds from the tank. Each set had 3 popping sounds. The sets were about 45 seconds apart. I have only heard the sounds that one night. Do you think I may have a mantis shrimp? <Perhaps this or a Pistol Shrimp> I immediately thought I had a mantis shrimp. I tried using the homemade bottle trap, but haven't caught anything yet. I've used shrimp and clam to bait the traps. I switch out the bait every two days. <Good> If you think this is a mantis, can you suggest any other trapping methods? <Mmm, there are some commercially made/modified products as well as DIY: http://www.google.com/search?q=mantis+trap&sourceid=ie7&rls=com.microsoft:en-US&ie=utf8&oe=utf8> I still have not actually seen the mantis. Last night I tried covering up the bottom of the rock where I heard the popping noise coming from in sand. It seems as though there were burrows under the rock, but the creature has not redug them. I don't want to buy and lose any more fish. If this is a mantis I have a spare 10 gallon tank that I would set up for the little guy (or girl). Thanks in advance for the advice, Joe <Do give the above search a read... and re the Alpheids on WWM: http://wetwebmedia.com/pistolshrimps.htm Bob Fenner>