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FAQs about Hermit Crab Behavior

Related Articles: Hermit Crabs, Crabs, Marine ScavengersFresh to Brackish Crabs

Related FAQs: Hermit Crabs 1Hermit Crabs 2, Hermit Crabs 3, Hermit ID, Hermit Compatibility, Hermit Selection, Hermit Systems, Hermit Feeding, Hermit Reproduction, Hermit Disease/Health, Land Hermit Crabs, Squat LobstersMicro-Crustaceans, Amphipods, Copepods, Mysids, Hermit Crabs, Shrimps, Cleaner Shrimps, Banded Coral Shrimp, Mantis Shrimp, Anemone Eating ShrimpMarine ScavengersCrustacean Identification, Crustacean Selection, Crustacean Behavior, Crustacean Compatibility, Crustacean Systems, Crustacean Feeding, Crustacean Disease, Crustacean Reproduction,

Hermit crabs changing shells en masse: Hermit Crab Beh 4/30/2009
Dear WWM Crew,
<Hi Guillermo>
Thanks for your amazing site! I am writing you with regard to a curious behavior that I have been noticing in my marine hermit crabs for the past couple of days. I could not find any information on-line and was wondering if you have had a similar experience. Here are the details:
I set up a 40-gallon saltwater tank seven months ago. It is currently stocked with one 4-inch Pink Spotted Watchman Goby (Cryptocentrus leptocephalus), one 3.5-inch Fuzzy Dwarf Lionfish (Dendrochirus
brachypterus), two small mushrooms, and 4-5 small Taro Tree Corals (Capnella sp.). I stocked the tank gradually, so most have been with me for between 3 and 5 months. I change 10% of water every week. I tested for water parameters this morning and they seem to be ok (ammonia, nitrate and nitrite are 0, pH is 8.4 and SG is 1.025).
<Sounds good, but your lion will require a larger home down the road.>
I added 4 Dwarf Red Tip Hermit Crabs (Clibanarius sp.) about 4 months ago plus 15 empty shells so that they could upgrade their homes. Each of them has changed shells once since then, one crab at a time. I added one Orangeclaw Hermit Crab (Calcinus tibicen) two months ago, and two Blue-Legged Hermit Crabs (Clibanarius tricolor) and two Staghorn Hermit Crabs (Manucomplanus varians) last Saturday. There are now nine hermit crabs in total. They have not displayed any aggression among them so far.
<OK>
The situation for which I am writing started happening the next day (Sunday). The crabs had scattered the shells over the last months, and I decided to pile all the shells up to create more open space in the tank.
The following morning (Monday), I noticed that three crabs had changed shells (one Dwarf Red Tip, one Orangeclaw, and one Blue-Legged). A few hours later, another three had joined them (one Dwarf Red Tip, one Blue-Legged, and one Staghorn that moved to a regular shell in front of my eyes!). By the end of the day six out of the nine crabs had changed shells.
<Heheh, my hermits did this too.>
My question is whether this behavior is normal, or whether it could be a sign of something going wrong in the tank.
<Not a sign of a problem>
I have heard that a hermit crab vacating one shell may generate a chain reaction where a smaller hermit crab moves to that shell, then another hermit crab moves to the shell of the latter, and so forth.
<Yes>
However, I think this may not be the case here because the shells in my tank have specific shapes based on which I am pretty sure that all of the hermit crabs moved to empty shells that I had previously added to the
tank.
<No, it is what it is, they are just swapping shells.>
Finally, I noticed today that the Staghorn Hermit Crab that had moved to a regular shell moved back to its branching shell, used it for a couple of hours and then moved back to its regular shell. Is this a normal behavior in this species?
<He\She\It is trying to find a shell it likes - Bigger than the one it has, but not so big to entice the larger crabs to try and take it.>
Many thanks for your help!
<No worries here, just enjoy the show.>
Best regards,
<My Pleasure>
Guillermo
<Mike>

Relationship between hermit and spaghetti worm 4/29/09
Hello all!
Is it common or well-known for a spaghetti worm to "host" or form some kind of symbiotic relationship with a hermit crab? I have a Mexican red-leg hermit using a Cerith snail shell with a small hole bored in it (I assume made by the predator which killed the original snail). There are two long tentacles coming out of the hole that to me look identical to a spaghetti worm. They wriggle about and withdraw just as you'd expect them to. Have you seen this before?
Thanks,
Emily
<Hello Emily. It's actually pretty common for Hermit crabs to form symbioses of various types with a number of different animals. One of the European species, Pagurus bernhardus, has been quite well studied in this regard. It routinely forms a symbiosis with sea anemones (several species) that it actually moves from old shells to new shells as it grows. Inside the shell there is a Polychaete worm, Nereis fucata. The crab and the anemone are assumed to benefit one another, the anemone by being moved about and perhaps collecting food from the crab, and the crab gets the benefit of the anemone's sting. As for the worm, there's no particular benefit to the crab, but the worm certainly snatches crumbs of food and lives somewhere relatively secure, defended by both the crab and the anemone. As for worms living inside burrows through the shell, the hermit crab likely doesn't notice or care about these, any more than you do the thousands of mites living in your eyebrows. There's little to no interaction between the two of them, though perhaps the burrowing worms might benefit from crumbs of food that drift about when the hermit crab feeds. Those worms would be in that shell regardless of whether the shell was occupied by a snail, a hermit crab, or was just sitting about on the substrate. As such, it's not really a symbiosis _per se_. It's better to think of a symbiosis as a situation where animals make particular efforts to interact with one another, and when doing so, at least one partner benefits. Cheers, Neale.>

Re: Relationship between hermit and spaghetti worm
Thanks for the info, Neale!! I think it's kinda funny, this crab is hauling around a freeloader! Pretty neat :)
<Some 10% of your (dry) body weight is bacteria. On top of that, there are mites in your eyebrows, amoebas crawling around inside your mouth, yeasts on your skin, and more besides! The only thing unusual about the "freeloader" you're seeing on your Hermit is that it's visible; most aren't. Cheers, Neale.>

Caring for Aquatic Hermit Crab  4/29/08
I don't mean to bother you but I haven't heard back from the email last week and I have looked on the website but can't find a response there so I thought maybe you didn't get the email the first time around.
I am trying to send it through again in hopes that you can help me with poor Sebastian's color.
<Thanks for re-sending. I don't recall seeing this>
When I started this new job March of last year, I thought it was really cool that they had this 125 gal salt water tank. They had a hermit crab that I named (of course) Sebastian. He was very active pretty much at all times. It wasn't long before our "fish guy" informed me that he would have to go; he was getting too big and aggressive for the tank.
<Is an aggressive, predatory species...>
He was evicted for not playing nice with the residents. He was eating the smaller fish. The person that maintained the tank prior to me arriving should never have put this type of crab in the reef tank.
<Actually... a false crab, Anomuran...>
What did I know, I was just fascinated by him so I asked if we could get a smaller tank to keep him in. That was last June, we have put him in my office so I get to keep a close eye on him and I have learned alot.
<... no such word>
I learned that they molt and bury it. He has grown a great deal and we have replaced his tank for a bigger one , 25 gal.. I have also noticed that he used to be a darker orange color where he is now a very light almost yellow color. Every time he molts, he gets paler in color. He is not as active as he used to be. I have tried to find out information on him but there just is not alot out there on the care of "Aquatic" Hermits.
<Actually...>
My fish guy doesn't know much on them as well. He just cleans the tank, he doesn't much care. He gets fed frozen squid and frozen silver fish.
<This is the source of "trouble", color-loss... No Carotenoids et al. >
I have attached a few pictures, the first one was before Christmas when he was dark orange and then the other was just a month or so ago; you can see the difference in color. He has molted again since the last one. He is on about a 3 month schedule. It takes him about a week of hibernating, then 3-4 days to harden then he is ready to eat again.
Is there any information you can give me or any websites you can direct me to. We have a handful more in the bigger tank but they are all pretty small, the biggest is the size of a quarter - down to a dime. I have been told that they are the red legged Hermits. They don't seem to grow much. If you could also let me know what kind Sebastian is that might help.
Kathy - FSI, Financial Solutions - Hermit Crab Lover
<Needs more/better nutrition... with pre-cursors that will supply the color elements. Please read here: http://wetwebmedia.com/hermitfdgfaqs.htm
and the linked files above. Bob Fenner>
Re: Caring for Aquatic Hermit Crab 5/7/08
Hello again,
<Kathy>
I just wanted to thank you for you great advise. We have added a great variety to his diet and his color is already improving. He has also gotten a lot more active like he used to be. My not so little guy never stops. He has even changed into a much larger shell - he thinks he is bigger than he is. I just love to watch him.
Again, thank you for your help. I have pasted it on to my fish maintenance person so that he also can learn from it.
<Ah, thank you for this upbeat update. Bob Fenner>

Hermit found a new home
Mobile Mushroom Coral (Coral Attached to and Occupied Snail Shell!) 3/30/08
Hey Guys,
<Scott F. your guy tonight!>
I have a potential problem with a hermit crab and a Mushroom Coral.
A few weeks ago, I bought a frag of Mushroom Coral that happened to attached to an abandoned snail shell. Unfortunately, a hermit crab
in my tank has decided to make a nice home out of it.
<Too funny!>
How do I go about getting the frag off that shell?? I'm worried he's going to move around and kill the coral. I've included a picture of this for
you all to laugh at.
Thanks!
Chris
<Actually, Chris- I'm not laughing! I'm kind of stoked for you! I've put this idea out there in some of my talks on aquascaping that I give at clubs- A living, moving bottom "substrate", comprised of Ricordea or Mushroom Corals attached to snails! Think about it- If you have 20 or so specimens attached to snail shells, you could have an ever-changing, super colorful coral display! Ok, in all seriousness, if this doesn't appeal to you, I'd simply provide a few larger empty shells for the hermit to colonize as he/she grows. It's inevitable that the animal will abandon it's current shell for a larger home when the time arrives. If you are VERY careful, you could use a razor blade to remove the Mushroom, but I would advise against it for fear of injuring yourself and two animals. In the meantime, I'd enjoy the antics of your "Mobile Mushroom". You can make a sort of game of it, taking bets from friends as to were it might show up! Good luck, and enjoy the show (for now). Regards, Scott F.>

Dardanus megistos Lifespan - 3/5/08
<Hi Andrew>
Any idea what the lifespan is for Dardanus megistos?
<Hmmm, good question. I can’t find an exact number for this species, but my guess would be somewhere in the range of 2-4 years depending on whether it’s a male or female. It seems that male hermits usually live a bit longer than females. The range I’ve seen for hermits in general (in the wild), has been anywhere from around 18 months to 10 years for marine hermits and up to 30 for land hermits.>
Thanks
Andrew
<You’re very welcome. I’m sorry I couldn’t give you an exact answer! –Lynn>

Re: Dardanus megistos Lifespan - 3/5/08
Lynn,
<Hi Andrew.>
Thanks for the response.
<You're most welcome.>
I have had mine since early 2003 so it is already 5yrs old.
<Neat, especially considering that we don't know how old it was when you got it!>
I don't know if it's male or female.
<That’s understandable. These hermits don’t have any distinguishable differences (externally) between male and female.>
Andrew
<Thanks for sharing. Take care, -Lynn>

Legless Crab... or not?  7/22/07
I have three hermit crabs who live in the same tank together.
<OK.>
I went to check on them earlier and saw several,
<Saw several what? I presume by the title you mean legs here...>
including the claw, lying in the sand next to one of the crabs. I didn't actually see that this crab's legs were missing (he's shy and rarely is seen by anyone), but I checked my other crabs and they're doing fine. I isolated the nearly legless crab in a tank by himself, assuming he had no chance to survive, but when I checked on him later, I saw he wasn't missing legs at all!
<OK.... so the legless crab isn't legless after all? Fuzzy wuzzy wasn't fuzzy was he?>
However, he is looking smaller and pinker than he was before.
<Sounds like he molted.>
I know it wasn't molting, because they were real, whole legs.
<Molting still may be a possibility.>
what is going on with my crab?
<I still suspect molting or perhaps you had 4 crabs and not three! Also in the future please I not i... Thanks, Mich>

Re: legless crab - 7/23/07
first of all, when crabs molt, they shed their exoskeleton. these were, as i said, WHOLE legs, not exoskeleton. second, i can count.
<Your written word doesn't so much convince me.>
i know how many crabs i have.
<Ever hear of hitchhikers?>
third, why do you and your god damn crabs
<I don't have crabs! I only keep snails.>
care if i use "i" instead of "I"? is it really that offensive to you?
<Because its proper English, and I have to correct it. Fix and resend. Read more reasons why here: http://www.wetwebmedia.com/QueryCorrsRefPg.htm
Mich><<Mmm, could be ecdysis... RMF>>

I couldn't help myself!   7/25/07
Crew,
<Mike>
I can't believe the grief you receive trying to help people with problems/questions who come to you! I had to comment on a couple of items in the daily FAQs. In regard to the individual upset about the search feature, a quick way to find what you want in a page full of threads is to do the Google search, open one of the links suggested, then in the pull-down menu of your web browser click edit, then find. Type in what word/phrase you are looking for and click "find next". Continue clicking "find next" until you are at exactly what you went to the page for. For the individual who "knows how many crabs s/he has", I "knew" I had no mithrax crabs in my tank until I found one hiding in the rock. Hitchhiker indeed!
Mike
<Thank you for this input and commiseration. Bob Fenner>

Lost Hermit Found 7/17/07
Hello Crew!
<Hello>
You guys/girls have been such a help I figured I owed you at least a good pic. I couldn't find my hermit for a day. All 3 shells were empty so I took him for dead. But the out of the back rock here he is in his new snail shell. My wife nearly died when she saw him. So here he is! Thanks
again. Notice the nice DSB you wonderful people told me to do. Ammonia 0 Nitrite 0 Nitrate 0?was 20-50 till the bed kicked in.)
<Thank you for the kind words, and thanks for sharing your pic.
James (Salty Dog)>

Re: Question about red legged hermit crab activity. – 06/28/07
Thank you very much for the quick reply!
<Welcome>
However, this being my first tank, I think I'm probably just being TOO cautious.
<Possible... but good!>
All of the crabs are moving fine, I never see them sit in a spot for more then 2-3 hours. But they do seem to be more active at night..
They are scarlet reef hermits.
<Ahh! Paguristes cadenati. These can take a while to adapt, be more active during light-hours...>
Thank you once again!
<Welcome! Bob Fenner>

Hermit beh.   5/8/06
I recently purchased two hermit crabs.  I have attached a link so you can see a picture of the type of species that I believe them to be.  When you get to this link there is a band of four pictures at the top and then one picture of a red/orange crab below that.  That single picture is what I believe to be the same species as my crabs.  My only question is, I just recently had one molt but he has not gone into a bigger shell yet.  I am just wondering, how often do they molt,
and how often do they need to move into a larger shell?
<Mmm, can be every few weeks depending on conditions favoring growth... food availability... sufficient alkalinity, biomineral content... and new/larger shell homes at about the same rate>
Any help you could give on this would be greatly appreciated. http://www.seafocus.com/species_crabs.html<http://www.seafocus.com/species_crabs.html>  Also, I love your website!
Katharine
<Thank you. Bob Fenner>

Lazy Scarlet and Blue-legged Hermit Crabs   11/5/06
Hello crew at WWM
<JM>
just a quick question
I have blue and scarlet hermits that lay around all day (for days) and are still in the same place the next morning ---
<Trouble... something likely amiss with your "water quality" here... possibly endogenous poisoning...>
no they are not dead (smile)-- however they are not actively feeding on the algae, in which I purchased them for.
<Most species of Hermits are not so inclined to do so... if there are other types of foodstuffs available>
  I also have zebra-legged which are constantly feeding.  I won't go into the parameters in my tank except to say that corals, fish and other inverts are thriving alive with voracious appetites) Nitrates are less than 20 ppm. Generally I do not use supplements except I do use Kalkwasser and a few (5) of drops of iodine (Kent marine) twice a week in a 75 gallon tank. I do feed the tank for the Brittle stars, maroon clownfish and the blue-lined surgeonfish (Acanthurus nigroris.  The question is if I am feeding the tank are the hermits losing interest in the algae because they are scavenging?
<Yes... you are likely correct here>
and is there anyway to encourage them to eat algae short of placing them on the live rock with the algae?
<Heee! Making other foods scarce>
and lastly I understand they are generally hardy is there a particular tank parameter that needs to be checked that would have a negative impact on the crabs??
<Mmm... are actually "false crabs", anomurans... Need biomineral, alkalinity as per your cnidarians... other essential macro and micro-nutrients can/should be supplied via feeding...>
Thanks in advance for your response
<Welcome. Bob Fenner>

Re: Singing, backward moving Crustaceans along the Euphrates?   8/14/06
Thank you very much for taking the time to answer.
   <Welcome... I have a classics minor from my first degree... a persistent interest in antiquities matters>
  Hermits chirp. Though I've never heard them there are recordings on line and mention of it on some sites.
   <Must stridulate at low amplitude and intensity>
  I thought the problem was with freshwater since the text says "river crabs" alongside frogs implying fresh water. I didn't think there were freshwater hermits. Is there anything else that looks like a crab and might make some kind of noise along a river or canal?
<Mmm, not a crustacean as far as I'm aware, though there are some freshwater hermits. I suspect that this reference may be to an insect of some sort... perhaps a cicada or cricket species. Bob Fenner>

Marine Hermit Crab Die Off and Stocking Density (Give, Your Crabs a Shell)  11/28/05
Hello Crew,
<Hello Tom.>
I really appreciate all the help you've given me over the last couple years...thanks!
<Glad you have found us useful!>
Today I'm hoping to get an informed opinion about what might be happening to my hermit crabs.
<Okay.>
My tank is a 30 gallon with a two-inch Fire Shrimp (Lysmata debelius), a Yellow Clown Goby, and a Firefish. It also has a small crab (size of a dime) and
probably a very small brittle star (all I ever see is his arms sticking out of a hole in the rock a quarter inch or so). These latter two hitchhiked in on the live rock.
<Good stocking choice so far, but watch out for the hitchhiker crab or at least try to i.d. it, could turn out to be something large/predatory in the future.>
The tank has a larger grouping of rock on the left, and a smaller grouping on the right, with a few inches separation in the middle. The Fire Shrimp lives in the left rock grouping, basically all alone. Everything else lives in or on the right rock grouping. I only mention this because it seems so odd that it might be a clue.
About two months ago, I ordered a dozen Dwarf Red Tip (Clibanarius sp.) and a dozen Zebra (Calcinus laevimanus) hermit crabs to control algae. I received generous counts, and actually started with about 30 hermits. As of today, I can count only 11 hermits. There may be a few I can't see, but 19?
<Honestly Tom I think the reason for this hermit die off is the original stocking density. These animals simply aren’t built to live a crowded arrangement like this but they are plagued by retailers recommendations of 1 per gallon, which is quite irresponsible (not you them). Anyway there are probably a few contributing factors including fighting over shells and insufficient food. Unless you were target feeding the hermits its unlikely they were able to survive simply as detritivores or scavengers. A more appropriate stocking level is 10 or less.>
I also believe a hitchhiker snail has disappeared.
<Possibly killed for its shell.>
So, what do you think is happening to the hermit crabs?
<See above.>
Tom
<Adam J.>

Hermit Crab Interaction  9/25/05
<Adam J.>
About 6 weeks ago I purchased a red legged hermit crab to help keep my 3 month old saltwater tank clean (and because the kids loved it) but yesterday
the crab was directly in front of the tank while it was eating. I sat and watched it for a minute and all of a sodden I saw a little crab come to the
very front of the shell and the elder then kind of pushed it back with one of its legs, like it was protecting it, it looked to be maybe a ? an inch in
size maybe a tad bigger, with well developed pinchers and all, it hung around for a minute or so then poof it run back into the shell were I
couldn’t see it, though I did see it for a minute today as well. I’m assuming that the little crab came along with the other when I bought it.
<Possibly but its more than likely a live rock hitchhiker.  Are you sure it was another hermit or did it look more like a flat “true crab” that was just pestering your resident hermit? It is extremely unlikely that this is a parent/offspring relationship.  In general crustaceans do not provide post-birth for the young, eggs are released into the water column where young hermits live a pelagic/plankton life until they can grow and find there own shell, they then fend for themselves.>
The big crab also molted within the last 2 weeks and is in a shell about 3 inches long, it was pretty dormant for about a week.
<Normal for most crustaceans to hide post-molting.>
Is it common, do they often carry babies in their shells?
<Not in my experience.>
What should I do to get the baby into its own shell?
<If it is a hermit it will eagerly go into any shell provided of appropriate size.>
What size shell should I get?
> your description, a very small one.>
Thanks, Richard
<Make sure to read through the WWM FAQ’s for more detail on hermits and their behaviors, Adam J.>

Re: Hermit Crab Interaction  9/25/05
I got a good look at what was inside today, I think that it looked like a little shrimp, could it be that the hermit just can't get it to leave or get
to it in the shell?  I think it may be one of those feeder shrimps, how big will that get before it comes out?
<Without a picture it is nearly impossible to tell what species of shrimp this is, there are a few types of shrimp sold as “feeder shrimp.” My guess would be a common live rock hitchhiker such as a Mysis shrimp, a copepod or amphipod.>
Thanks
<Anytime, Adam J.>

Hermit crab behavior  8/26/05
I have 4 red legged hermit crabs and I keep noticing one crab filling the other crab's shell with sand.  What is the crab doing?  Is this normal or is it trying to kill the other crab?  Thanks, Michelle
<Bizarre... maybe trying to get the other crab out of the shell so it can occupy it. Bob Fenner>

Hermit out of his shell 07.04.05
One of my hermits is out of the shell and crawling around the tank unprotected, what can I do????
<Keep the humidity up, offer him a variety of shells with different size openings, and if possible put other crabs in a different enclosure until this guy figures out what he is trying to do, they are very vulnerable when out of their shell.  Oh, also provide some damp sand a few inches deep, he may be feeling the need to molt, and will need to bury himself.  Gage>

- Staghorn Hermit Crab -
Hi,
We've had a Staghorn hermit crab for some time now and have noticed that over time his shell has gotten dark and shriveled-like.  I'm assuming that it is dead or dying. <I think you are correct.> Tonight, we have noticed that the crab has abandoned his shell and has moved into one of our spare regular hermit crab shells.  But has not managed to flip the shell upright yet (too big perhaps?) <Perhaps give him some help.> Will he live in a regular shell? <I would like to hope so... as neat as Staghorn hermits are, they rarely get to live for long in captivity because their shelter just doesn't make the transition. Perhaps this one will have a better chance because it's moved on.> My husband has put a few smaller shells around him. Is there anything else we can do for him? <Flip him right side up.>
Other info about tank:
55 gallon tank
260 watt light
tank mates:
coral beauty angel
bicolor angel
clownfish
several damsels
snails
cleaner shrimp
2 electric blue leg hermits
1 red hermit
Any advice is greatly appreciated.
Thanks!
Kimberly
<Keep an eye on him, and make sure he gets upright. Cheers, J -- >

- Staghorn Hermit Crab, Follow-up - 30 Jun 2005
Thanks for getting back to me so quickly and for providing me with all your input. <My pleasure.> By the next morning, he was upright and doing his thing (sifting sand) as always, just like he did when he was in his original shell.  Now, several days later, he seems to be doing fine.
<Excellent - glad to hear.>
Thanks again!
Kimberly
<Cheers, J -- >

The Gathering - Hermits
Good evening!
<And to you>
I haven't written in a long time. When I did, you and your teammates were a great help. My tank is up and running great. 150 gallon SW reef tank. Up for 10 months. Almost fully stocked. Never had any problems. Thanks to your site. This isn't really a question, more of an observation. So the last couple of evenings when the lights go out I notice my hermits acting kinda strange. (At least I think it's strange). When I shine a flashlight in the tank, all the left handed hermits are gathered on the same rock huddling together. (About 12 hermits) On another rock, all the electric blue hermits are huddling together as well (6 hermits). Finally on another rock, all the scarlet red hermits are gathered as well. (4 hermits)
This is new to my tank. Almost every night I will observe the tank with a flashlight. Night observation is almost better than during the day. I'm fascinated with all the life at night. The gathering of the hermits has only been going on for three nights. Have you or your mates heard of this type of activity? Common? Strange?
<Mmm, "hermits of a feather/species do flock together"... particularly during spawning times... you might log your observations, look for positive correlation with moon phase/tides>
So much for not asking a question...
Oh, also last night I noticed one of the left handed hermits releasing eggs into the water. (At least that's what I think it was). A left handed hermit kinda lifted the shell off her/his back and hundreds of little (little) eggs/things were released into the water from her back. They looked similar to live brine shrimp. Does this sound like common hermit activities?
<Mmm, yes>
Were they releasing eggs/hermits? 
<Likely so>
I though this was pretty interesting, so please let me know what you think. 
Thanks for your time and great site. I still read it daily. 
Dan
<Me too! Bob Fenner> 

My hermit crab has left his room
My hermit crab left his shell, what should I do? <He's probably gotten too large for the shell to be comfortable, I would toss some more hermits in there or some empty shells and he'll find one that fits.  Good Luck! LinearChaos.>

Hermits fading
Dear WWM Crew,
Thank you for the great site! I have browsed through
your website but did not find the answer to my
problem. I have 10 blue legged and 2 scarlet hermit
crabs in 55 gallon tank. I have recently noticed that
my scarlet became more of an orange color and at least
one blue legged has faded in color too. Can you
suggest any reasons for that so that I could address
it before they get worse. Thank you! Artem
<Likely nutritional, though water chemistry/quality can definitely play a/the role here. Color change per se is not an indication of good or ill-health though... You might check your water, augment, actually directly feed your Hermits some vitamin/supplement (e.g. Zoe, Selcon) soaked foods. Bob Fenner>
 

Hermit crab mating dance?
Hello WWM Crew,
<Kari>
I watched something strange with my hermit crabs this evening and I was
wondering if it was mating, or just simply checking out each other's shells.
If you have any clue - please share!
<Okay>
I bought 5 Clibanarius hermit crabs from my LFS (only one is the C. tricolor
with the blue legs, the others have reddish legs). I noticed one of them was
getting "attacked" by all of the other 4 at the same time. I separated them
and then they all ran back and "attacked" the same one all over again. I
decided there was nothing I could do, so I'd just watch and see how it
played out.
Three of the smaller "attackers" eventually lost interest, leaving a large
blue-legged "attacker" in a tan shell (blue), and a red-legged "victim" in a
white shell (red). This is what happened:
1. The blue one turned the red's shell over, put his front legs into the
white shell, and kept knocking his tan shell on the red's white shell.
2. The blue one came out and pulled the red one out of his white shell. The
red one crawled out and sat on top of the blue's tan shell.
3. The blue one came completely out of his tan shell and went into the white
shell.
4. The blue one sat happy in the white shell for a little while
5. They rolled around for a bit
6. The blue one came out of the white shell and went back into his original
tan shell.
7. The red one went back into his original white shell and everyone was
happy. They just walked away from each other.
The corresponding pictures are attached. Is this just the blue one checking
out the red's shell and deciding he didn't want it after all? Or was this
some sort of mating?
<Not mating... different species... perhaps a test for the red one's shell...>
If the red one in the white shell was "in heat"
(for lack of better term) then that would explain why all the others kept
attacking it... Anyway, it sure was interesting and I'm curious to know what
was going on.
Thanks!
Kari
<Me too... these false crabs (anomurans) are almost constantly contesting each other for food, space, shells... Do provide a few extra shells of various sizes for them to sort amongst. Bob Fenner>


Hermit crab molting.
I have two salt water hermit crabs from California, I think, I live in California. I have had them for about a year. I have a 55 gal salt water tank with 5 small fish, 1 lion fish, 1 small star fish, and a sea anemone. The hermit crabs have been in the tank the longest.  I bought a bunch of shells for them to move into as they crow, and one actually moved into the biggest shell, which seems HUGE for it's body size, the other has remained in it's original shell this whole time. The one that moved is the bigger one of the two, but they are both quite small.
One day I saw them attached and I thought they were fighting, so I separated them, but after many times of this I thought I should let them do their thing, because what if they were trying to mate? Were they trying to mate? They were attached for about 8 hours once, and then I saw a bunch of pinchers left where they were once attached.  I looked at both hermit crabs carefully and saw that they were fine, all parts in place. So I came to the conclusion that one was helping the other molt. But just the pinchers?
Weeks later I see a poor dead hermit crab out of it's shell (home). I take it out and throw it away. Then I realize both hermit crabs are still in their homes alive! I couldn't figure it out, so I decided that they had babies, and one died, or one lived and a parent died. The reason I did not think this was just the remains of a hermit crab that had molted is because white tissue was part of this dead thing, and it looked like a whole hermit crab, not just the outer casing of it.
Weeks later more pinchers are found in a pile, and I conclude that the other hermit crab that did not molt before just molted. 2 weeks after this discovery I just found another poor dead hermit crab. This one I still have in a bowl of water because I want to know if it is just a molting, or if it's really a hermit crab dead. Once again it looks like a real hermit crab, it has white tissue, it's tentacles are there, along with it's eyes, it's mouth, everything seems to be there. How is this a molting?
But how is it not is a better question. They can't reproduce hermit crabs that are adult looking can they? But I still have two hermit crabs in the tank alive.
HELP?
Thanks in advance Denae.
***Hello Denae,
You're not sure you live in California, or you're not sure your crabs are from California? :) They are in all likelihood a tropical species, as the native California hermits do survive at reef temps, and are not collected for the trade.
That aside, you have no worries. Crabs do not help each other molt, and what you were witnessing could have been either combat or a mating, I can't say for sure. In any case, crabs do not clone themselves and create adult sized offspring, so you have simply experienced a molting event. Or, your crabs have at any rate. The entire exoskeleton is shed, eyes, mouth parts, everything. It's easy to mistake for a dead crab. No worries, and you can feel free to dispose of that discarded exoskeleton. :)
Jim***

Molting Crab 20 Aug 2004
I'm in a panic, so please answer ASAP. <I just got this a bit ago and let me try to help you, MacL here with you.> Two weeks ago to the day our hermit crab molted.  It is a fascinating process as you've described.  My panic is this: I'm not sure he (Capt. America) is alive. <Great Name!>  It does not appear that he has come out of his shell in two weeks for water or anything else..  I'm assuming he has eaten some of his exoskeleton since it looks as though he is hanging on to it. <Does it seem to be still attached in some way to him? Possibly an incomplete molt?>  I can visibly see him inside his old home.  I'm just not sure he is alive. <I think he's had an incomplete molt my friend.>  When I tried to "smell death", I don't know if I'm getting the exoskeleton smell, or his death smell.  I did a little tapping on his shell to see if I could get a response, but there was none.  I've
sprayed water into his habitat for moisture, however I only did it today.  <I think that's where your problem may lie.  Spraying of them and or the tank for humidity needs to be done pretty much daily.... helps them to breath easier - literally. Too many hobbyists are not informed of this and the crabs suffer slowly over time (evidenced by inactivity, incomplete molts, etc and I'm pretty sure that's what's happened here.> I've been careful to keep his water sponge filled daily.  It appears that he is getting darker in color, but I'm not positive. His partner, Betsy Ross, died about 2 weeks before he molted.  Any thoughts on how I can find out if he is still with us?  <Keep spraying the tank every day and spray him some but don't drown him.  Take a look at these websites and see if they help you.  http://www.landhermitcrabs.com      http://www.hermit-crabs.com >
I don't want to stress Captain America out anymore than he might already be.
By the way, Captain America chose to molt on top of his sand.  Does that
mean anything?  <Usually that he's trying to get the shell off of his body.  Keep the faith I think he will be okay if you can get him some more humidity.>
Thanks a million for your help and I've learned so much by using your web
site.  <Good luck Pat and please let me know what happens.  MacL>
Pat Stone

Re: molting crab right after iodine added
hello again! <Hello Jimi, MacL here with you this fine evening.>
Question also regarding my crab. I've had him for probably 2mo. now, he seems quite happy and has snuggled up to an anemone from which he rarely leaves. Since deciding to start a reef tank, I've been reading about all the additional chemicals I need to add to support it. I read about iodine and saw that I needed to add it for anything that molts. So, I added 1ml last week, and after I did a 20% water change last night, I added another 1ml to tank.
I woke up this morning to find what I thought just the remains of my beautiful little crab. But, after lifting a few rocks, found him very much alive looking "fresh" in his new outfit. Question is: Did my crab molt because of the added iodine? <The iodine in proper dose will assist in the molt.> In other words, did it make him molt, or was he probably in need of molting anyway and the added iodine just helped him to do so? <I've read that its possible the iodine causes the shell to itch and they shed it but most people believe that they are ready to molt and then it helps them to do it successfully.>  And is it possibly for a crab to molt too much? How often do they do so? <Depends on the crab.>
Like I said I read that iodine aided in molting -- but good grief, I didn't realize it would work so quickly..... and now, I'm kind of afraid to keep adding it on a regular basis even at the recommended dosage, because I also read that overdosing can be BAD. <Definitely get a test kit, you can overdose it.> Is there a test I can do for iodine, I thought I read that there wasn't - so how can I be sure there is enough, but not too much in my tank? <Salifert has a test kits and so does Seachem.  Please if you dose it get a test kit. Good luck, MacL>

Aha!  Here It Is.... Land Hermit Molting Behaviour - 08/24/2004
I'm in a panic, so please answer ASAP.
<Hi Pat, I am now in possession of the previous email.  Glad to hear we're talking about land hermits, here - with all due luck, this *may* be a positive outcome....>
Two weeks ago to the day our hermit crab molted.  It is a fascinating process as you've described.   
<It *is* fascinating, isn't it?  What always amazes me is the amount of time it takes, versus, say, an aquatic shrimp, who is done molting in minutes, and back to its old self in just a couple days.>
My panic is this:  I'm not sure he (Capt. America) is alive.  It does not appear that he has come out of his shell in two weeks for water or anything else.   
<A concern, indeed, but really, it can take a *long* time before they come out again.  I have a couple Ecuadorian hermits (Coenobita compressus) that are still underground, after about a month - but every few to several days, I can tell one has moved a bit (the fellah dug under right next to the glass - how convenient!).  This does tend to be a very long process.>
I'm assuming he has eaten some of his exoskeleton since it looks as though he is hanging on to it.    
<A good sign.>
I can visibly see him inside his old home.  I'm just not sure he is alive.  When I tried to "smell death", I don't know if I'm getting the exoskeleton smell, or his death smell.   
<You would notice a rather strong, very fishy/oceany smell.... it's very distinct.  If he's underground, it may not be strong at all, though.>
I did a little tapping on his shell to see if I could get a response, but there was none.   
<Apparently he's not underground.  If it makes you feel better, were I him, I certainly wouldn't respond to someone thinking on my shell if I were molting....  :) >
I've sprayed water into his habitat for moisture, however I only did it today.   
<Yipes - only once in how long?  How high is his humidity?  This is a very, very crucial point - if it's not humid enough, their gills will dry and harden, and they will literally suffocate.  Think of these as aquatic animals that just happen to live on land....>
I've been careful to keep his water sponge filled daily.   
<Good - I'm hoping this is enough to keep his humidity high?  Do you have a hygrometer?>
It appears that he is getting darker in color, but I'm not positive.
<Hopefully this, too, is a good sign....>
His partner, Betsy Ross, died about 2 weeks before he molted.   
<So sorry to hear that....  But perhaps this has at least made you aware of that strong fishy smell?>
Any thoughts on how I can find out if he is still with us?  I don't want to stress Captain America out anymore than he might already be.   
<If he's all alone in the tank (as he *should* be, for his safety, if he didn't go underground to molt!), I would go ahead and give him more time.  I'm pretty confidant you'll recognize a dead-crab smell if you smell it.  If you are completely and utterly uncertain as to his status, and really really need to know, pick him up (if he's alive, he will not fall out of the shell) and spritz him with water (he should react in some manner to this - probably by scooting farther into the shell).  If he is still absolutely unresponsive, place him in his fresh water dish.  If he does not respond after a minute, chances are pretty slim that he's alive, I'm afraid.  I would recommend against this, unless you absolutely need to know and cannot wait on him.  I am not convinced he's dead, yet, and would not do this, were it me in your shoes.>
By the way, Captain America chose to molt on top of his sand.  Does that mean anything?
<Possibly, yes.  Is the sand moist enough for him to dig into?  Or is it totally dry?  IF the sand is dry, hermits can't burrow and tunnel in it, and would be forced to molt above ground.  Otherwise, he may have been stressed, sick, or injured, and for some reason unable to dig.  Or perhaps he just likes the view - unfortunately, it can be very, very difficult to determine why they sometimes molt above ground.>
Thanks a million for your help and I've learned so much by using your web site.
<I do hope this has been of some use to you.  I would also strongly recommend checking out some land hermit forums -  http://www.landhermitcrabs.com/ and http://forums.hermitcrabassociation.com/ are a couple decent ones that I've found.>
Pat Stone
<Hoping for the best for you and Captain America,  -Sabrina>
<Ahh, and a P.S.:  PLEASE respond and let me know if you've received this.  I am hoping there are no further complications!  -Sabrina>

Land Hermit Molting Behaviour - II - 08/24/2004
Oh, thank you so much for your reply.  The original message I sent to mike@wetwebmedia.com I'll resend to your address.  
<Great.  I have received and responded, and hope that you have received the response....  Also, you can send to "crew@wetwebmedia.com" with questions - I'm not sure if the mike@ goes anywhere or not, as we have two or three mikes with us....>
Thanks a million and please respond with any questions.  Since Captain America and Betsy Ross were my first hermits, I'm not sure what kind they were, but Captain had a purple/bluish claw.  
<Actually sounds perhaps like an Indonesian crab - Coenobita brevimanus - but could be any of a number of others, as well.>
I bought them at a shopping mall last November.  The worst thing that may have happened is my going on the internet to learn more about them and subsequently changing their sand and such.  I probably should have left them alone.  
<I totally disagree - the *best* thing you can do for your animals is to learn about their needs and meet those needs.  I suspect above anything that the care (or lack thereof) that they received at the mall stand was so deleterious and neglectful that the animals could not survive, regardless of the care that you gave - I *strongly* urge against purchasing from shops such as these....  If you purchase an animal from a shop that you are confidant is neglectful, you are only *helping* that shop to continue hurting the animals in your care - purchasing from them keeps them in business.  No matter how sorry you might feel for an animal at such a place, just remember that buying it is dooming another.  That kind of a tradeoff is unacceptable, to me.  Please note that I am *NOT* in any way scolding you for having purchased Captain America and Betsy Ross there - I am *ONLY* hoping to guide your future purchases away from supporting such establishments.  It is better to find a pet store that cares diligently for their animals.  Moreover, perhaps you can even *help* a local pet store to gain a better understanding of how to care for hermits.>
I really grew fond of these little guys.  
<Easy to do....  I totally understand.  I am so sorry for your loss, and truly hope you see some improvement in el Capitan.>
Actually, as I think about it, Captain probably has been still for almost 5 weeks....doesn't sound too good does it.  
<Indeed, it does not.  At this point, with it having been *so* long, I think I would go ahead and pick him up and inspect him, spray him with water, and watch for any reaction.  If none, I'd place him in his freshwater dish and see if that brings about any response.  I am quite surprised that you haven't noticed a strong fishy odor, though - my fingers are still crossed, but I do fear it doesn't look good at this point.>
Please just tell me the best way to find out if he is still alive without overly stressing him.  
<Just as above.>
Thank you again for your help.
<I'm sorry I don't have a whole lot of good news for you - but I *do* most certainly hope that you will try to find a good store for hermits (to be honest, I've been pleasantly surprised about the Petco stores near me - pretty darn nice setups for their hermits!) and try this again.  Don't give up entirely on keeping these creatures - they are amazing and very fun animals.>
Pat Stone
<Wishing you well,  -Sabrina>

Hermit Crab Fighting or Mating
Hello, <Hi Leah, MacL here>
I have had 6 hermit crabs 2 very small, 2 small, and 2 medium for a little over a month now. They always romp around and play. Today I noticed that the 2 very small hermits were attached to each other...like one had one of its legs or claw inside the others shell. <Very likely trying to pull the other one out. When I see this I usually separate them and move them to opposite sides of the tank.> I thought it strange so I separated the two to opposite side of the tracks. Just to see the one crab climb back and reconnect with the other. <I think one of them really wants the others shell.> I figured they were playing so I left.  When I re-entered the room 5 minutes later one of them was completely out of its shell and the other was hovering over top of it. I immediately jumped to the conclusions that the other crab was trying to kill the one out of its shell. I picked up the shelled crab and moved him away and put the a shell next to the other crab...it gladly climbed in and has been hiding all day.  The other crab has been stalking it and just staring at it from a distance because it can't get back to where it is hiding. Is one of these crabs trying to kill the other? <Not necessarily kill but definitely after the shell.> (we have plenty of other shells that it could choose from!!) <Sometimes they want what they want> Or is it just a determined mater.....PLEASE LET ME KNOW! <I think you should just continue to keep them as far apart as you can.> I keep checking on them to make sure they're ok! Thank You, Leah

The Offspring said, "You got to keep 'em separated!" 
>My fianc? and I went to Florida last Nov. and bought a red hermit crab. 
>>Not knowing from where, I can only hope that you didn't go to Florida specifically for this purpose. 
>We've had him for 5 months, and he's been alone since then. We bought his new friend about a week ago, and is smaller than he is. (Not by much though). Any how this morning we found Bailey's legs, and small pincher laying in the tank. 
>>Hermit crabs, for the most part (of the aquatic persuasion), generally do NOT consider other hermits to be "friends". They consider them "real estate" and competition. 
>She was out of her shell. My fianc? picked her back up, put her in a much larger shell, cause Buddy had stolen hers. 
>>Uh oh. She'll be uncomfortable in an improperly sized shell. It's also very important that hermies get shells of the right species. These crabs need to be separated somehow, or these battles may likely continue until one (likely the newer addition) dies. 
>Will she grow her legs, and small claw back? 
>>She should, yes, within a few molts. 
>I know that the hermit crabs molt, but I haven't seen one do it before. What signs do you look for? 
>>Well, if this were a land hermit then there are definite signs to look for. Aquatic hermits, no, they'll just hide out and molt overnight, come out in a day or two. 
>Could Buddy just not like the other crab? 
>>Chances are if Buddy can, Buddy will kill the other hermit crab. Again, not knowing if we're talking aquatic or land hermits, this is hard to say with any real certainty. If you've got land hermits, then please Google (on our site as well as open search) "land hermit crab" and you should find many excellent sites. A few will even help you to identify your species. This is important for knowing how to feed AND water them properly, as well as provide proper housing. Land hermits require sand deep enough to bury in to molt. 
>What Can I do? 
>>What I said. 
>Sincerely Rob & Becca 
>>Good luck, keep them separated so the new one has a chance to recover, and find her appropriate digs. Marina

Stuck on You
I have two hermit crabs and they are stuck together.  All you can see are the two shells, you can't see the crabs at all.  They have been this way for at least 12 hours.  Are they dead?
<Ryan with you.  No way to tell for certain, but wait it out.  Just leave them alone, as your other hermits will be happy to snatch up an empty shell.  See ya, Ryan>
Thank you,
Lorraine

Magic Crabs! The Endless Crab-fest-o-RAMA!
>This might sound like a preposterous event/question, but I swear it's all true. 
>>NO! Really?? Let's hear it.
>Two weeks ago I bought 6 red-tip hermit crabs for my 55 gal saltwater tank to see if they would get along with my other tank inhabitants (2 percula clowns, yellow tale blue damsel, bubble tip anemone, and a red brittle starfish) before I bought more. 
>>More hermits? If so, you would probably be doing them a favor if you kept their numbers around oh.. maybe one/10gallons.
>Since then two have died, I scooped their little bodies out of the tanks (they died out of the shell, probably because another crab killed them and took their shell) and threw them. 
>>You just threw them, tossed 'em like a cat? In the house? Where'd they land? Does it smell now? (Sorry, I cannot resist.) When you say "out of the shell", I assume you mean their flat, the shell they use for a home, not the shell that covers their little exoskeletal bodies, correct?
>Now today, I have noticed that I still have 6 crabs, I counted them ten times to make sure I wasn't counting anyone twice.
>>Heh.. good thing you didn't end up with 60! 
>Now for the question:
>>Indeed!
>How is this possible? 
>>They molted and you tossed the molted exoskeletons. All creatures that are bound by an exoskeleton must molt to grow/make repairs, as they haven't got skin like us endoskeletal beings.
>Can the crabs produce offspring this big this quickly? 
>>Nope, they can't, plus I bet you didn't have any extra flats even if they could.
>If you could comment on any of this I would greatly appreciate it.
>>Ohh.. I think I'll stop right here. A LOT of folks get really confoozled when hermit crabs do this molting thing. They're quite good at it, and it looks and feels for all the world like their dead, lifeless bodies.
>Thanks, Jessica Ressler
>>You're welcome Jessica, and no, you're not going crazy. Marina 

Blue legged hermit aggression - 1/27/04
Hi crew,
some 6 months ago I bought a couple of tiny blue legged hermit crabs from my LFS, they warned me at the time they may have trouble with the existing 5 red legged hermits, <Sometimes known to become aggressive for shells> anyway they have continued to grow well and are now much bigger than the red legged hermits but I am concerned they are now
feasting on my livestock! <OK> 2 days ago I notice my blue starfish who has lived happily for the last 9 months has some chunks out of one his legs, <Check water chemistry. Starfish are indicators of water chemistry issues (high salinity, temp swings, or general poor water quality) Also depends on the type of hermits but likely not a dwarf blue hermit's doing> some weeks ago I also caught one eating a snail. <this they are known to do. When they like a home they just move in regardless of inhabitants. Kind of like a house and the fridge is stocked with food> today I discovered the two hermits were eating my cleaner wrasse who I put in the tank 2 weeks ago, the wrasse seemed fine last night. <Likely the wrasse died and they are feasting on the result of the death. Again, depends on the hermits we are talking about. I would try to ID them just to make sure>
do you think these are scavengers or predators? <More than likely scavengers> should I feed them or remove them? <You should always supplement them with food. Keep an eye on them. Check your water, and ID them to be sure you don't have a more aggressive predatory type crab. Good luck. ~Paul>
Ron

Scarlet reef hermit
Bob,
I have been using the website to help me with a lot of questions, its great! My question is, Do Scarlet reef hermit crabs molt their hard bodies, I know they switch shells when they grow out of their current ones, however this morning when I looked into the tank I saw what looked to be the body of one without the shell laying on the Live rock is this common and nothing to be alarmed about or do I need to go on a mission to find the killer?
<All crustaceans, including the Hermits undergo ecdysis (molting) to allow for (generally positive) growth... and often leave their old exoskeletons about (better to leave in the tank as the old owner may ingest/incorporate the matter into its new one... and it won't pollute your system).>
Thanks as always, Mike
<The next few days after molting are dangerous for the "soft bodied Hermit"... don't disturb the landscape if you can avoid it. Bob Fenner>

Re: scarlet reef hermit
Bob,
Thanks for the ultra fast reply!!!!! One last Question what does the molted
exoskeleton look like? 
<Initially, like an exact model of the original... sans the insides... eventually, just bits and pieces...>
I'll try to describe it the best I can. The legs
are red, and look exactly like the legs on a living crab, same red
color/length, the abdomen looks pale white, almost a milky color and seems
to wave in the current freely, it appears it has those small legs use to
move in and out of the shell, however its not too large in size, but then
either was the hermit to start, and its laying upside down. I don't know how
greatly this will help but I'm so concerned for in the case its dead, ill
need to make sure its not something in the tank killing them.
<Might be a molt... with some of the mineral and matrix content going... Not to worry. Bob Fenner>
thanks,
mike

My hermits are becoming reclusive!  07/23/03
<Hi Chris, PF here with you tonight>
I picked up 9 "zebra hermits" (although I swear they're blue-legged hermits by visual identification) at the LFS for some hair algae control, as well as 4 Astrea snails. For the first few days, the hermits chewed away happily at the algae, and tended to congregate in small meetings.
It's been a week, and all the hermits have seemed to crawl into crevices in the LR. They all have their antennae (?) wiggling about on their faces, but they remain in there at leisure. Are these creatures nocturnal? I'm somehow doubting that. I know any aquarium won't live up to what my ideal 'bustling with life' scene might look like, but I was hoping for a little more action out of these guys. Should I be looking towards water quality issues? Everyone deciding to molt simultaneously?  The Astreas seem to be faring well, happily chewing away at the algae. 3 seem to be doing fine. The last one is quite lethargic, moving at a snail's pace, as it were.. I will be doing ammonia/nitrate tests in a few minutes.  pH is hovering at 8.2; s.g. at 1.024; temp ~82F.
P.S. Since I last wrote to WWM a couple of months ago, my so-called "hard cure" has long since become quite rewarding, and I could not imagine ever wanting to buy "fully cured" LR! Tons of creatures lurk in the depths of my tank, including strange translucent tentacles (approx 1mm in diameter) that shoot out of tiny holes in the LR and suck in detritus with their vacuum-cleaner like tips (any ideas on what that might be btw)?  Thank you for providing this wonderful service WWM crew!  Enjoying this hobby, even if I am making all the beginner mistakes one at a time, - Chris
<Well Chris, they could be blue legs in zebra snail shells. A rose by any other name... As for their behavior, remember, they don't read the same books we do. I've certainly seen my animals doing things that they're not supposed.  The critters on the rocks, are probably some sort of worm, maybe the spaghetti worm, check here for more: http:// www.wetwebmedia.com/polychaetes.htm   Mistakes, well, I try not to make beginner mistakes myself, but all new ones. ; ) At least it was one at a time, and not all at once.  Have a nice night, PF>

Hermit crabs in Fiji
The other night, here in Fiji,   there were
about 2,000 hermit crabs all trooping up from the beach into the woods
at
the back of the house.
I'd really like to know why they were doing this.
<Me too... there are "crab aggregations" timed to tides, moonlight... that involve reproduction en masse. Maybe this is one of those? Optimizing chances collectively, decreasing likelihood of annihilation by predation... Bob Fenner>

Re: hermit crabs in Fiji
Thanks for your thoughts. I see that land hermit crabs have to go to the sea to spawn. Maybe these were coming back. Or do they spawn and die?
<As far as I'm aware, all spawn and return to land for consecutive years. Bob Fenner>

Hermit Homes, Aiptasia
Mr. Fenner
First Off I would like to say I really like your book I have found it useful
in so many situations. <Ah, deeply gratifying to hear/read. Thank you>
I have several questions. One Is: In your book you say that Nudibranchs
are not suited for home aquariums because not much is known about there
feeding. But recently I have been seeing many ads for lettuce Nudibranchs.
They say they take care of hair algae. Do These really work or is it just a
gimmick.
<They can work. Not so specific in foods (algae) that are taken...>
Another do blue leg hermits and scarlet hermits outgrow their shells.
<Yes>
If
so how often do they need new ones and how much bigger should they be. 
<Provide several of varying sizes and let them choose>
What
happens if they don't get them.
<Not a pretty story. Get larger, no where to move, get eaten by their fellows, other species>
Lastly in my reef tank there is this "thing" attached to my live rock.
it's hidden by a small pile of rock about a cm. high) and it has several
hair-like, very thin, tentacles about 3-5in.) that reach out into my tank's
gravel and pulls up stuff from the gravel. Do u know what this is? 
<Sounds like a Glass Anemone/Aiptasia... read about them on the WWM site>
Does it sting? 
<Yes>
It seems to put out a lot of waste it excretes it all at once and it
seems to be a lot for how small it is
<Bob Fenner>

Hermit crabs
Hi Mr. Fenner.
I have another question once again.
Do hermit crabs also molt, or not since they keep looking for bigger
shells? 
<They do indeed molt>
I ask this because if they don't molt, then I have something
going on in my aquarium that might sound strange. I have six red legged
hermits, and two that are very dark, almost black. I've had them for
months, and every so often I find what looks like the remains of one of
them. I say remains because it looks like they have been eaten, and all
that is left is the front part, like the head, and legs. sometimes the
remains are red, and other times they are dark, which shows that both
types that I have are doing this. It's not a clear shell like when my
different types of shrimp molt, but actually looks like the remains of
the body. Yet when I take a roll call, all of my hermit crabs are still
alive, and well.
<Good observations, relating... No worries... keep supplying a selection of "new homes/shells" to move in to. Bob Fenner>
Thanks Greg.

A curiosity (Hermit Crab behavior, speculations)
I don't have an aquarium or keep hermit crabs but I'm familiar with these
little guys because I grew up on the Texas Gulf Coast... Rockport, TX to be
exact. Many years ago a friend and I spent most of the summer at the beach.
As always, we saw several hermit crabs doing what hermit crabs usually do in
the surf. However, one day (I can't recall if it was late June or early
July) we noticed what had to be Thousands of hermit crabs congregated in one
area of the beach that was sheltered by a concrete wall and large concrete
slabs so the surf was very calm. They were everywhere; some were stacked up
on each other five or more crabs high. Others were just crawling about in the
shallow water, frantic. But so many! Being curious, we started watching
what they were all about. Well, it was amazing. I have never seen such
shopping for outerwear! The hermit crabs in the shallows were trying on each
other's shells. Some willingly and others not so willing. They were trying
on the occasional empty shell found on the bottom or a likely piece of trash
or junk floating about. Some were crawling around shell-less, having lost
their shell to a rival we supposed. At this point, we made a quick trip to
the closest sea shell shop and bought several 'homes' for the homeless
hermits. We 'sold' all the new 'homes' and could have used more. We also
experimented with the hermit crabs that were stacked up on the concrete slabs
and when put in the water they were just as eager to explore a change of
residence as the others. By this time it was late and we had to go to Our
homes but we made plans to come back to the same spot the next morning. The
next day when we arrived the hermits were gone, for the most part. And the
ones that remained were not in the least interested in trying on the new
shells we had brought with us that morning. Do you have any idea what was
going on with these guys? 
<Home shopping spree? Mmm, does seem (albeit teleologically) that there is some species survival value to such "let's change out at the same time" shell-swapping behavior... as opposed to not switching at about the same time, place... in the way of avoiding predation... and maybe some greater degree of reproductive behavior going on all the while...>
It didn't seem to have anything to do with
outgrowing their shells and we didn't detect any 'romantic' goings on. I
would really like to know if anyone else has seen this type of behavior.
Thanks. Jacki
<Have noticed Hermit aggregations at times/places... and thought maybe they were coincident with food availability or tidal action... Don't know... but perhaps others will chime in with the posting of your note on the Daily FAQs: http://www.wetwebmedia.com/dailyq&a.htm
tomorrow. Bob Fenner>

Hermit Crabs & Behavior (looking for a new shell or Amore?)
Bob,
<Anthony Calfo in your service>
Quick scenario and question about Hermit Crabs. I currently have a
system set up with LR, few fish, Xenia, Snails, & Hermits. I stocked
the tank with just 12 Blue Legged Hermits (look identical to and I
believe are Clibanarius tricolor) and 6 Left Handed Hermits (Calcinus
laevimanus). Today, I noticed that one of the larger BL Hermits was
literally attaching itself to another BL Hermit (this one was quite a
bit smaller). It was moving its front legs and accessory feeding
appendages quite a lot, but it did not appear to be outright trying to
extract the smaller BL Hermit. I watched for a while, and another BL
Hermit came along and was also watching. The third BL Hermit climbed
onto the larger specimen, and finally I broke this up to see what would
happen. The smaller BL Hermit that was being 'hassled' was then put at
the other end of the tank.
About four hours later, the same BL Hermit had found the smaller one -
and was performing the same behavior! The same third BL Hermit found
them again, and then, one by one, more BL Hermits joined until there
were six all in one front corner of the tank. I thought maybe they were
hungry and trying to eat the smaller BL Hermit (although, not that
small), so I went against my judgment and got some frozen Mysis shrimp.
However, when I returned to put it into the tank, the 'party' had
somewhat broken up. I fed them anyway, and all seem to have stuck
around to eat except the BL Hermit that was the focus of attention.
Finally to my question: am I looking at hungry crabs, or some attempt at
mating? Good Health, Ryland
<hmmm... that depends...were you playing any Barry White or Luther Vandross music at the time? Er,... never mind. The behavior that you have described is not so specific as to indicate mating. They could have just as easily been trying to commandeer a shell...cheeky little monkeys, they do that all the time. When one is about to outgrow it's shell, it gets quite frisky and even tries on smaller shells (I suppose it can't tell until it puts it on!). With hermit crabs of all kinds, it is very important to always have extra and larger shells on hand. Do find and put some in...I wont be surprised if you see a shell change within a week. Do let us know. Kind regards, Anthony>






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