# Halloween/Moon crabs care???



## claymore

I bought a pair last week end at a herp show. 

I've reesearched them all this week and have a good understanding on care and what not. 

The only conflicting info I read was on salt water... Some sources say use it and some say Don't!

So which is it???  

Has anybody else on here kept these marvelous little crustacians???


Thanks 

Clay


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## naturejoe

*crabs*

I have kept them a few times and each time they would do great for months and then would die.  I did not offer any saltwater.  I think it is best to emulate nature as much as possible and these crabs dig burrows below the water line to create little pools of saltwater.  There must be some reason.  Good luck.


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## LeilaNami

I believe it is the same with hermit crabs.  They will drink the fresh water but offer salt water in a bowl as well because it is very important for long term health. I believe it is used more frequently when the crab is ready to molt.


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## Andrew273

Been a while since I kept hermit crabs and never had any other kinds. I think they put the saltwater on their gills to breath. I could be wrong but I definitely recommend giving them a bowl of it.


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## RoachGirlRen

I would provide a pool of freshwater and a pool of brackish/saltwater. Make sure that you use MARINE SALT however, not table salt, as iodine and caking agents can harm the crab and the mineral content of marine salt is different from most food salts. 

ETA: I just did some reading on these guys because you've made me curious, and while several studies have indicated that chloride and sodium are not limiting factors for the species, it is suspected that some ion in marine water is, as they do not tend to distribute too far inland from coastal regions(1). So chances are if they are suspected to need it in the wild, it should be offered in captivity. It also had some notes on diet in the wild which includes a significant amount of leaf litter and seedlings, so I'm thinking it may be beneficial to include leaf litter and sprouts in their diet as opposed to just processed crab diets. 

1. Dry season distribution of land crabs, _Gecarcinus quadratus_ (Crustacea: Gecarcinidae), in Corcovado National Park, Costa Rica - Griffiths/Mohammad/Vega

Reactions: Like 1


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## spydrhunter1

There's a good article on crab street journal on mixing sea water for hermit crabs, it may work for these guys; http://crabstreetjournal.com/xoops/modules/news/article.php?storyid=20


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## claymore

Thanks Ren! Is this the same Ren from FatFrogs?

I just finished their tank today! I'll have to run out tommorrow and grab a dish for the salt water. Anyidea how big/deep it should be? do they have to submerge themsel;ves in the salt water? 
Anyways here are some pics!


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## LeilaNami

You want the dish to be large enough to get their body in and deep enough for them to get a substantial amount on their bodies.


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## dtknow

I've observed these in the wild. They were abundant on the beach under drift and around some mangroves in Gauanacaste, Costa Rica. Previous studies have shown they cannot survive if only given access to seawater. Their ionic balance is a little lower than pure seawater and they cannot osmoregulate well enough in that required direction. 

I would provide them some fresh water, but also have some brackish/sea water for them to drink to maintain their salt balance. They can also drink out of moist substrate so perhaps freshwater container is not strictly required

To the person who posted tank photos. I think you need more substrate(I would do a mix of fine sand an coconut fiber moistened so they can burrow), and a smaller water section. These crabs do not submerge themselves in the wild(their burrows do not touch the water table, unlike mangrove crab Cardisoma, which also appears in the trade...care for this sp. will be different). Even when releasing eggs into the sea they try to stay as dry as possible, going out to far could mean being eaten by fish. 

Mainly herbivores/detritivores in the wild but opportunistic. 

RGR: your advice is spot on. I do wonder if the inability for them to go inland is due merely to the need to go back to the sea to breed, or perhaps a habitat preference issue.


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## Galapoheros

I think these def need the ocean waters to breed.  I have collected these on S. Padre Island, at least they look extremely identical, and the ocean is a big place so I assume they are the same species.  The behavior is prob like the xmas Island crab vid I saw.  They might not need salt water to exist in their solitary life though.  But I would always have salt water available to them, they are def associated with it.

"the ocean is a big place so I assume they are the same species."  haha, that wasn't very good logic but there is not much doubt in my mind that the same species can be found in s texas.  I will look for some pics I've got somewhere.  I didn't bring any back home but it makes sense to keep them like RGR mentioned, offering both fresh and saltwater.


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## dtknow

Galapoheros:
Not sure where the OP's crabs are from. But if they are from the Carribean and are Gecarcinus lateralis than thats the sp. that occurs in some spots on the Gulf. They only visit the ocean to breed, and even then try to stay out of it lest they get swept in.

No one has bred these in captivity yet. They'd probably need exposure to the lunar cycles to sync up for breeding. The zoea could be raised on rotifers followed by artemia nauplii(contrary to popular belief crab larvae CAN be raised in captivity, and based on the papers I've read it does not sound too difficult).


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## Galapoheros

I could have put this in another thread but we can compare here.  They do look a little diff.  I saw some that were almost all purple there too, I have a pic of one of those somewhere too.


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## dtknow

My bet is the "all purple" ones are Cardisoma guanhumi.


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## LeilaNami

dtknow said:


> The zoea could be raised on rotifers followed by artemia nauplii(contrary to popular belief crab larvae CAN be raised in captivity, and based on the papers I've read it does not sound too difficult).


The what-a-what? My crab speak is definitely lacking.  I'll have to look this stuff up lol


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## Matt K

I have to agree with dtknow.  Thier captive rearing is not difficult but does require some attention, much like propogating jellyfish really, which I have done with several species 

While in Costa Rica, I have regularly seen crabs wander inland and found them near fresh water supplies, but this indicated to me that they alternate with some regularity thier intake of salt and fresh water.  So (at a guess) if it were I, there would be access to both in the enclosure or make thier water source a little less than brackish.


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## AudreyElizabeth

I bought one of these a few years ago and kept it in a tank much like the one pictured. The crab 'appeared' to be doing well until it molted, and it lost four legs!    My LPS often has these crabs, but I hesitate to buy another after that bad experience. (The crab died not long after the bad molt.)
However, I did not know at the time that they needed brackish water. Could this have caused the bad molt?


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## RoachGirlRen

If there are important trace minerals in the brackish/salt water, it could have been a cause of a bad molt; unfortunately the exact function of salt/brackish to their survival is not firmly understood. Thus it is favorable to provide both fw and sw/bw "just in case." 

However, more often than not, a bad molt is from a humidity problem (be it air humidity or a hydration issue) or if the exo itself is bad, a diet problem. As mentioned this species consumes a lot of leaf litter in the wild; I would wonder if insufficient chitin because problematic for them if fed say, your typical hermit crab food.


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## dtknow

Also, in the wild they'd probably be at the bottom of a very deep and cozy burrow.


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## RoachGirlRen

That too; I know hermit crabs do OK with several inches of damp substrate, but I don't know how much that cuts it for a species that burrows more deeply.

dtknow, do you know if they are opportunistic or obligate burrowers? Ie. do they tend to take over burrows of other species or do they dig their own? I'm thinking of eventually trying my hand at these guys and I'm just thinking of housing options.


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## claymore

First off thanks for all the replys!! 
I started this thread and walked away for a few days and blamo it has a life of its own! 

Ren - They seem to dig they're own burrows and revisit them each day. I'm guessing they would use the same burrow in the wild over and over again, unless they were forced to relocate for food or water or cave in. This species likes to burrow deep! At least mine like to. I have 4.5 to 5 inches of sand on the land portion and they are burrowed all the way down to the bottom!

I am going to relocate them into a twenty long this week end. 

I'm taking the advise dtknow and providing more land space and thicker substrate for deep burrowing.

I have a bowl of salt water in there now and I've seen them dipping their claws into it and bringing it up to their mouths. So I think it is a good idea to provide both fresh and salt water!

Like Ren stated above, their diet consists of leaf litter and scavenging. I've been trying a number of diff food items, like... Lettice, slices of apples, pecies of carrots, dried fruit, fresh bannanas, and for protein... a few fresh killed crickets, freeze dried brine srimp, and even a little of my cats wet food (fish flavored).   So far they don't seem to be picky eaters. They are messy eaters though!LOL  

But I can't find any info on a feeding scheduale! I don't want to feed to often and I don't want to starve them ethier.

Any ideas???


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## AudreyElizabeth

Best I remember I had mine in about 8 inches of sand at the maximum depth. The crab wasted no time digging the burrow, and continued to use it until its death. I fed it a variety of different foods, crickets, lettuce, fruit, ect. Never messed with hermit crab food. 
The tank was a ten gallon with one third of it a pool, with a filter running. I had lots of problems keeping sand out of the motor, and had to rinse it out at least twice a day. Certainly needed a better thought-out filtration system.


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## Galapoheros

After thinking about it more, I think there might be a relatively untapped hobby niche here that hasn't been refined yet.  I'd keep saltwater and freshwater available on either side of the cage, and have deep sand sub.  I picked up several on Padre Island going towards the beach that had a bunch of eggs.  How long and how many stages does it take for the saltwater larvae to become terrestrial?


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## RoachGirlRen

Claymore, if they eat chiefly plant matter, they probably should always have at least some kind of food source available. Leaf litter has a very high C:N ratio, which basically means you have to eat a whole BUNCH of it to get much nutritional value from it. Obviously if you are feeding fresh veggie/fruit it is a more nutrient-rich food source (not dramatically though, fruit/veg is still something like 25:1 compared to animals which are 5-10:1 or something... it's early, don't quote me on that), so perhaps you don't need to feed as large a quantity, but it might be worth while to have a little something to nibble at always available; heck maybe you could provide a little bit of leaf litter if you have a pollution-free source available. 

I'm actually interested in this topic now so if I have time today I'm going to dredge up some primary research articles on their feeding behavior just to see if there is any more concrete info than logical speculation.


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## Galapoheros

Also, I've had the thought of "osmosis" and a "turgor" pressure(sp?) kind of thing in my head as it relates to salt and molting and salt attracting moisture while molting.  Man, I'm just going by my senses there, I have no knowledge of that at all .


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## dtknow

Galapoheros:

It generally takes about 7-8 molts before young crabs actually look like young crabs(and in the case of land crabs)  come ashore. Based on larval rearing studies the process of raising the zoea in SW should take about a month.

I'd love to give it a try over the summer if I have a month to spare and an ovigerous female crab.(I need to move to Texas y'all have all the cool stuff!) I suspect they will not breed in captivity without the lunar cycles however. That is how they time their breeding in the wild. Also, rain seems to be important.

I've heard of lots of people getting fiddler crab eggs even in quite improperly designed enclosures for them(tough little buggers apparently, no need for a mud flat!). If you are interested in raising land crabs they might be a nice one to beta test larval rearing on since they should spawn fairly easily. 

The crabs take in water prior to molting and store it in special sacs(pericardial sacs, very enlarged in land crabs.). Aquatic crabs, or crabs that otherwise molt underwater, do not do this to anywhere near the extent of land crabs.

Getting land crabs to spawn is likely going to take some time(I've only heard of 2 cases of land hermit crabs laying eggs in captivity, and only in one were they fertile).

-I have read way too much crab biology during my free time!


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## Galapoheros

That's some good info!, thanks, just the kind of stuff I was wondering about.  I like crabs, they are interesting to watch.  I was playing around with them on the beach.  These would put up a fight when I would grab them off the road but calmed down REAL fast.  Finding females with eggs was pretty common.  Some nights I wouldn't see any but other nights I'd come across 5-10 of them.  I saw a HUGE one climbing over a curb, don't know what kind it was, there was a car behind me so I couldn't turn around fast enough, I couldn't find it.  Also, down where the Rio G meets the ocean, I found huge land crab claws behind the dunes on the flats.  They reminded me of giant fiddler pinchers.  Some looked 5 inches long.  I drove over there trying to road hunt whatever those claws belonged to but I never saw any.


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## dtknow

Big fiddler crab pinchers sounds to me like Cardisoma guanhumi...the mangrove crab. Perhaps some predator discarded the claws on the dunes because to catch them you will have to get into the mangroves(and probably get quite muddy!). They do occur further inland but must be able to hit the water table with their burrows(which can be meters deep).

You ever see ghost crabs(Ocypode) where you are? I know they occur occasionally as far North as the Carolinas. They are relatively small crabs that burrow in the beach or the dunes above it and can run incredibly fast. They are the only "land crab" specialized as a predator, most of what they eat is smaller creatures off the beach occasionally adding in detritus sifted from the sand as in fiddlers.

RGR: They dig their own burrows. However, they will not hesitate to take over an unoccupied burrow instead of digging a new one.

MattK: You should start another thread about that.


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## Galapoheros

I saw several remains of the big crabs on a flat that looks like it fills with a shallow layer of water and might take a month or two to dry up.  I've heard of that sp before.  Yeah the claws I saw looked a lot like the big claw on this crab.
http://images.google.com/imgres?img...nhumi%22&start=20&ndsp=20&um=1&hl=en&lr=&sa=N
Ghost crabs, yeah ..back in the 70's when I was a kid we'd chase those down at night and keep them in buckets and watch'em for the rest of the trip.  I remember I caught a mantis shrimp, it was white and at the time, I thought it was the coolest thing I'd ever seen!  A brother caught a baby blue crab.  My dad made us put the two together in a bucket on the way home instead of separating them, I was prob 10.  The crab ate my shrimp on the way home, I cried and was really mad because I told him that would probably happen, haha, it's funny to think about now.  Anyway, yeah I'd go find snails, sand dollars and hermit crabs when I was a kid on vacation at the beach, I found a big scallop one time between sandbars.  I'd bring the stuff back home in a bucket of SW and sand, of course everything would die in a few days.


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## dtknow

I think any of those sp. would be fun as pets. Different species of Cardisoma, including guanhumi show up in the pet trade once in a while too.(usually called some name like patriot, king crab, coconut crab, etc. etc.)


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## LeilaNami

Use collards, mustard greens, turnip tops, or kale instead of lettuce.  Lettuce holds next to no nutritional value compared to the other leafy greens.


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## dtknow

A diverse diet would definetly help. They are definetly not picky eaters though so if you can't offer them all kinds of fresh veggies, don't fret. They eat mostly leaf litter in the wild.


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## Amenagerie

I bought some of these on a whim once and they died also after about 4 months. They were sold to me as Halloween Crabs.  
I just wanted to share my experience in hopes it helps to understand them better. 
They did eat just about everything we'd give them. I kept them in a large kiddie pool with only about 3" of sand. I put a pile of slate rocks on one side that had lots of hiding areas and that was where they'd hang out most of the time. 
They turned out to be very good climbers. After a couple escapes, I had to put a piece of plywood across the top of the pool over where the rock "mountain" was. And even then I found them on top of the plywood a couple times. They would get on their mountain and stretchhhhhhhh their claws out to grasp the board and pull themselves over. They really were intriguing animals. 
I also gave them crickets, but live ones. They would get very animated and I had to make sure everyone had one or else they fought. 
I gave them a large basin of fresh water which I would see them drinking, but I never saw them submerge themselves in it. I had ramps inside and outside the container. 
It's been a couple years and I'd love to have more, but not without a better understanding of how to care for them. :8o 
This thread has me thinking of starting a new enclosure. It's spring, the kiddie pools are on the shelves now. :clap:  However, I think I want something even larger, or at least deeper to provide them with better opportunities to burrow. THIS time I'll be sure to take pics.


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## NecrochildK

I've got two right now, my last one lived a bit over a year after I got him, he was pretty fully grown when I got him too. But I've always kept mine in fresh water and they do plenty well. My current two are almost two years since I acquired them, though one's a little bit of a runt.


Btw, this is a verticle shot. The back of my terrarium has a viney board they love climbing. I just wish they were as outgoing as my last one, he was quite social these two hide so much, this shot was so rare, about a glimpse of them once a month.


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## MudCrabDude

I've 4 Gecarcinus crabs, ordered from Mr. Todd Gearheart, this past March and they seem to be still doing well (*knock on wood).  In fact, one molted with me right on the day of the deaths of M.J./F. Fawcett, so it was a very eventful day, to say the least, and I almost overlooked this event, literally, had I not looked down on the tank:







Here he is trying to eat the shed carapace:







His eating of the carapace kinda reminded me when I try to wolf down a whole New York - style pizza by myself...though admittedly he was much neater about it.  It was funny watching him rotate the carapace around to get a nice bite.  

I presume this is the same species shown in the photos at the beginning of this thread.  It's a male and prior to the molt, when I first got him, the widest point of the carapace was measured at about 1 and 3/8ths of an inch and was missing a leg, but after the molt, he measured about 1.5 inches and grew the lost limb.  He pretty much ate every milimeter of the exo right after the molt as well.   

Admittedly, this old 2.5 gallon tank in the photos was much too small , but since then he's now residing in his own 10 gallon tank.  The other 3 (all females -slightly larger) are also kept separately in each of their own 10 gallon tanks.  

The substrate is of playsand, moistened to "sandcastle" consistency similar to my land hermit crabs (if not a little more moist than that, but not too wet).  I provide separate dishes/pools of freshwater and seawater/brackish water, and provide some broken pieces of cuttlebone in addition to their diet of coconut pieces, hibiscus blossoms, sprouts, frozen freshwater crabs, etc....


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## What

dtknow said:


> I think any of those sp. would be fun as pets. Different species of Cardisoma, including guanhumi show up in the pet trade once in a while too.(usually called some name like patriot, king crab, coconut crab, etc. etc.)


I hear they are even called the "Giant Satanic Graveyard Robber Crab"!


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## MudCrabDude

What said:


> I hear they are even called the "Giant Satanic Graveyard Robber Crab"!


Yeah, I'm speculating that was actually a full grown _Gecarcinus ruricola_ similar to what is shown in this page:

http://www.upng.ac.pg/mirc/black_crab.html

Just your garden variety leaf-litter foragers/omnivores, I presume.  I recall reading they're probably the biggest _Gecarcinus_ that can be found around the tropical Americas (well, at least bigger than the _quadratus_ or _lateralis_ species).


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## Iwannabreedcrab

*Breeding Moon Crabs and where to buy females?*



claymore said:


> First off thanks for all the replys!!
> I started this thread and walked away for a few days and blamo it has a life of its own!
> 
> Ren - They seem to dig they're own burrows and revisit them each day. I'm guessing they would use the same burrow in the wild over and over again, unless they were forced to relocate for food or water or cave in. This species likes to burrow deep! At least mine like to. I have 4.5 to 5 inches of sand on the land portion and they are burrowed all the way down to the bottom!
> 
> I am going to relocate them into a twenty long this week end.
> 
> I'm taking the advise dtknow and providing more land space and thicker substrate for deep burrowing.
> 
> I have a bowl of salt water in there now and I've seen them dipping their claws into it and bringing it up to their mouths. So I think it is a good idea to provide both fresh and salt water!
> 
> Like Ren stated above, their diet consists of leaf litter and scavenging. I've been trying a number of diff food items, like... Lettice, slices of apples, pecies of carrots, dried fruit, fresh bannanas, and for protein... a few fresh killed crickets, freeze dried brine srimp, and even a little of my cats wet food (fish flavored).   So far they don't seem to be picky eaters. They are messy eaters though!LOL
> 
> But I can't find any info on a feeding scheduale! I don't want to feed to often and I don't want to starve them ethier.
> 
> Any ideas???


I have four Moon Crabs three males and only one female...can anyone tell me where to purchase sexed females from? I do know the females have smaler pincher claws.


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