Marine hermit crabs? ID, care  – 08/27/07
This past weekend I was in Cape Cod, MA. Some friends and I were in the ocean (just ankle deep), and we saw a bunch of tiny hermit crabs in the water. They are only the size of my thumb nail, maybe slightly larger.
Well of course we made the dumb decision to bring some home, and now I have 4 of them in a water bottle with salt water and sand and rocks in it. So far they are fine. I went to a pet store today and bought a bunch of stuff for them. But once I got home and did more research I am realizing to my horror that I don't think these are land hermit crabs like I was thinking. Can I keep them in captivity or will they die?? I bought a little plastic container and sand and a sponge for them, but I think they need to be fully submersed in salt water don't they?? Should I get a whole salt water aquarium system for them?? I'm not finding much info on how to care for Marine hermit crabs, and I'm afraid these cute little guys will be dead any day now!!!!!! Please help!!! Thanks.
Natasha (If you need a picture of them to identify I can send one later.)
<Hello Natasha. Identifying a hermit crab to species level is very difficult without a photo. But in the cooler parts of the North Atlantic then species of the genus Pagurus are most common, both along the North American and European coasts. So I'm assuming you have one of those. They are indeed fully aquatic hermit crabs, though they are well able to tolerate exposure to air for some time, and will scuttle about in very shallow water even with half their bodies exposed. But for long term care you will need to set them up a "coldwater marine" aquarium. This is not difficult. Firstly, you'll need a tank around the 10 gallon mark. Then you'll need a filter. I'd recommend a simple air-powered box filter filled with ceramic media and a bit of filter wool. There's no need for carbon or anything else. The aquarium needs to be filled with artificial seawater -- that is, water with about 35 grammes of *marine aquarium salt mix* added per litre of water. Using a hydrometer you need to aim for a specific gravity of about 1.027 at 18 degrees C, the maximum safe temperature for these crabs. Try and keep them cooler if you can. I have a little program called 'Brack Calc' on my web page ( http://homepage.mac.com/nmonks/ ) that lets you relate the required salinity (35 g/l) with whatever temperature you have and the specific gravity you can directly measure. Beyond this, keeping hermit crabs is easy as they are quite hardy and adaptable. They are omnivores, mostly feeding on algae, organic detritus, and carrion. In the aquarium almost anything will be accepted, from algae pellets to raw seafood. Don't overfeed them though. Apart from the fact these animals don't need extra light and don't like warmth, in terms of basic care they are otherwise similar to tropical marine hermit crabs. Hope this helps, Neale>

Hermit Crab Possible Misidentification   8/19/07
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First let me say that your site really is great. When I buy aquarium books, I look for your names, period.
Concerning this email, I would appreciate a response, but it need not be public (although I don't mind if it is).
<We post all>
I believe the photo in "Hermit Crabs, Use in the Marine Aquarium Hobby" (http://wetwebmedia.com/marine/inverts/arthropoda/crabs/hermitcrabs.htm)
labeled *Phimochirus *[aka *Pylopagurus*]* holthuisi* (Provenzano, 1961), Red-striped Hermit, is really *Clibanarius vittatus* (Bosc, 1802), Thinstripe Hermit.
*
<Have tried to look just now... via Google mostly... to discern... Humann, does state that the Red-Stripe Hermit has "one claw greatly enlarged... movable pincer is white"... which in viewing the original (aquarium) image of mine is obviously not the case...>
My reasons:
1. Color and Markings:* The photo you have in "Hermit Crabs, Use in the Marine Aquarium Hobby" (http://wetwebmedia.com/marine/inverts/arthropoda/crabs/hermitcrabs.htm)
looks nothing like the photo in
http://www.gsmfc.org/seamap/picture_guide/Hermit%20Crabs/phimochirus%20holthuisi.pdf,
but does look like the photo in
http://www.gsmfc.org/seamap/picture_guide/Hermit%20Crabs/clibanarius%20vittatus.pdf
.*
2. Claws:* Even if the photos were of such poor quality that color and markings were not reproduced well, notice the one huge claw of *P. holthuisi*, and the matched claws of *C. vittatus*. I do not think the one crab in your photo just happened to have matched claws at that point in time because I have seen many photos on the web that are *supposed* to be *P. holthuisi*, and all of them with the same longitudinal stripes on the legs also have matched claws. Obviously, these photos are incorrectly labeled, also.*
3. Habitat:* *P. holthuisi* is "Found on shell, sand, mud and coral bottoms from 15 to 104 m." *C. vittatus* is "Common on harbor beaches and on borders of mud flats; rock jetties; water line to 22 m." Perusal of the web (your site and others) indicates that people who find hermit crabs looking like your *P. holthuisi* photo have found these guys very near the waterline, definitely not 15 m below it.
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Elsewhere on Your Site
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Some confusion in general: Note the entry in "FAQs about Hermit Crab Identification", http://www.wetwebmedia.com/hermitidfaqs.htm:
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Re: hermit crab question 8/1/06
*Thanks for your patience. I believe that they are red striped hermit crabs.
<Clibanarius vittatus?>
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Spread to the Web
*
Interestingly enough, I believe the misidentification has spread to others on the web. You guys have a very powerful site! The whole thing is becoming circular. E.g.,
<Yes... perhaps too powerful... and circular...>
http://www.saltcorner.com/sections/zoo/inverts/crustaceans/hermitcrabs/Pholthuisi.htmhas
Bob Fenner's picture of (what I contend is)
*C. vittatus*. It is a higher resolution photo of the one on your site, so people can more easily (incorrectly) identify their hermit crabs.
<Will post today as our "daily pic"... Am assured here that your ID is correct>
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Recommendation
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If I am correct, I think you should at least do #1.
1. In "Hermit Crabs, Use in the Marine Aquarium Hobby" (http://wetwebmedia.com/marine/inverts/arthropoda/crabs/hermitcrabs.htm), either change the picture or change the description. As you have pointed out elsewhere, *C. vittatus* does get rather large, 10 cm at least (Adam J. said he had one (actually, he said it was *P. holthuisi* in a 6" shell).
2. Add *C. vittatus* to your list of hermits.
3. You might want to go through the references to *P. holthuisi* and correct whatever was said about them.
Thanks for considering this,
Scott Allen Rauch
--
Scott
<Thanks much for this Scott... will addend/fix today. Sending notes to récif et al is going to be a bit more extracted task. Cheers, Bob Fenner>

Mystery Hermit   2/11/07
Hello,
<Hey.>
You guys run a great website that I use often.
<Great.>
However I have looked all over the sight to try to identify this hermit crab that I got in a group of dwarf blue hermits. He is a green color with a single vertical stripe going down each leg with white spots on his claws.  
<Oohh sounds like Phimochirus holthuisi, I too received a juv. mixed in with some other hermits once.>
he looks very similar to the dwarfs hermits.  The color of the green is similar to that of an emerald crab.  Sorry that I can't get a pic for you right now, I loaned my camera to a friend.
<Google the name I gave you above, I willing to bet that's your crab.>
I am worried that he might not be reef safe any ideas?
<Mmm....the problem with the crab I named is not so much that he attacks sessile invertebrates but that it attains a rather hefty size and becomes a little clumsy.>
So, far I haven't seen him going for corals or anything yet but he is only maybe 3/4 in shell included.
Thanks for the help.
<Anytime.>
Steve
<Adam J.>

Aquatic Hermit crab identification  10/26/06 Greetings, <Salutations> Recently I have become quite interested in aquatic Hermit Crabs, and I have been doing quite a bit of digging for information on them. It seems there is very little information on them available, outside of WWM. <Mmm... bunches of non-husbandry information re these anomurans in large libraries> I have also managed to pick up a few oddball Hermits from my LFS, which I have not been able to identify for the life of me. I've Googled, and I've Googled, and I've Googled.... <Not Google-able presently> But to no avail, I have not been able to ID them. Either I am not good at searching for things on google, or the photos/information are extremely hard to find/non-existent.     <Just not ready-referenced> I have included the pictures of the oddballs on this e-mail. I was hoping you guys could help ID them? I've included 5 pictures of 3 different types of unidentified hermits, labeled "A", "B", and "C". More pics on the way as well, I've got 2 others that I can not ID, but they are hard to photograph. Once I have gathered enough info and gained enough experience, I am considering starting a webpage for aquatic hermit crabs. There just doesn't seem to be any one webpage with enough info, pictures, and scientific names. Oh, and if Bob Fenner is reading this, you may remember me from IMAC! I was one of the puffer guys, and we also talked over e-mail a bit in the past. Regards, -John <Ahh! Pleased to make your re-acquaintance. Can't recall from my feeble memory what these might be... do "practice" setting them up on a rock... waiting patiently for their re-emergence to photograph with a bit more detail... and send along again. Bob Fenner, out away from references... in Thailand>