Tag Archive for molting

Hermit Crab Surface Molt

Hermit crabs typically go about their molting business below ground away from your prying eyes and nosey tank mates but this isn’t always the case. Sometimes you will find yourself with a surface molter on your hands. Surface molts can be very cool for you but additionally stressful for the crab.

Coenobita clypeatus - Purple Pincer Hermit Crab Surface Molt

Coenobita clypeatus – Purple Pincer Hermit Crab Surface Molt

C. compressus surface molt. Top most leg is a newly regenerated limb.

C. compressus surface molt. Top most leg is a newly regenerated limb Photo by Nichole Edwards.

Let’s look at the best way to handle a surface molter.

  • First do not touch or move the crab! (unless you feel you must to ensure it’s safety)
  • Second find a way to securely isolate the crab.
  • It is extremely important that your tank temperature and humidity are in the proper ranges at this time.
  • Do not mist a soft hermit crab, there is danger of causing an infection by over wetting the soft exo.
  • Do not remove the shed exoskeleton (skin), your molter is going to eat that and it’s important that he does!
  • Do not place your molter in total darkness. Normal light cycles are needed!
ISO bottle should be pushed all the way to the bottom of your substrate so there is no way for another crab to burrow in from below.

ISO bottle should be pushed all the way to the bottom of your substrate so there is no way for another crab to burrow in from below.

In place isolation of a surface molter can be accomplished by cutting the bottom off of a 2L plastic bottle and then placing it over the molter and pushing it down (gently!) into the substrate, all the way to the bottom of your tank if possible. This will keep tank mates from cannibalizing the molter while it is soft and defenseless. Remove the lid from the bottle top to allow air flow.  If you can’t get the bottle all the way to the bottom of the tank, keep an eye out for signs of other crabs trying to burrow their way in.

Kritter Keeper used in main tank as an ISO for surface molters

Kritter Keeper used in main tank as an ISO for surface molters

If you simply can not securely isolate the surface molter, you may be forced to move them. You need to have some sort of container ready, preferably something that can stay in the same tank where the molt has occurred. Very small kritter keepers are ideal for this as they have secure lids but are vented for air flow. As gently as possible move the molter AND the shed exo to the isolation container. Do not poke, prod or otherwise futz with the molter.

Post Molt Photo by Jenny Velasquez

Post Molt Photo by Jenny Velasquez

When the molter begins moving around on his own you can gently move him from the 2L bottle enclosure to a larger isolation tank stocked with food and water and a hut. When your molter has fully hardened up it’s time to go back to the main tank. Monitor the molter and the tank mates for signs of aggression. If you witness ongoing aggressive behavior, place all crabs upside down in your water pools. This will rinse off the molting scent and everyone will smell the same again. Unless there is a problem, bathing is UNNECESSARY and should not be done. Aggressive behavior is an indicator of a bigger problem, usually over crowding or inadequate diet.

I understand that it is very fascinating to be able to watch the molt process happening but remember your presence is threatening to the hermit crab at this time. If you want to take photos, do NOT use the flash! Limit your photo taking and time spent hovering and try really hard to let your poor little crabbie do his molting business in peace and quiet.

Coenobita rugosus post surface molt munching on some delicious exo:

Ask Milo – Protecting a molter from a tank mate

Shawn writes:

What should I do for my crab gypsy she went down for a molt shortly loosing hr companion sparky? I got her a new friend just before she went down now parodite keeps trying to dig her up. I tried putting gypsy in the molting tank but she was unhappy there anyway I can tell how she’s doing? Or how can I keep parodite off the area until gypsy is ready to come up? I have a small ( gypsy) and a tiny ( parodite) in a ten gallon with 6 inches of half sand half eco earth.

Hi Shawn!

Isn’t it frustrating when you have a naughty crab on your hands? The best way to isolate Gypsy is to cut the base off of a 2 Liter plastic bottle (like pop comes in) and press it down where Gypsy is dug under. You must be gentle so as not to collapse the burrow but if you press it all the way down to the bottom of your tank there is no way Parodite can get to Gypsy. You will want to remove the cap to allow air exchange. If you aren’t sure exactly where Gypsy is you could use some plexiglass to divide the tank in half and then use another piece to lay over the substrate above Gypsy. That way even if Parodite scales the divider he/she can’t dig down.

Hope this helps!

Your friend in a pinch,

The Newbies Guide to Hermit Crabs

Coenobita compressus

Let’s Get Started!

First and foremost use the SEARCH BOX and SEARCH, SEARCH, SEARCH! Our site has a ton of information and nearly every question that a new crabber is trying to answer, has been asked here before. We work hard to maintain a current and extensive library of articles to help you. We do have a forum but it is not monitored and you may not receive an answer right away.



Have you found yourself an unprepared parent of a hermit crab or two? Are you prepared to give them the proper habitat in which they can survive long term? If so, here’s a very basic list of supplies to get you started.

A glass tank

  •  go as big as you can afford
  •  it doesn’t have to hold water
  •  it doesn’t have to be new (check the newspaper,craigslist, yard sales)

A secure lid for the tank

  • a mesh lid with a solid barrier on top to retain humidity is ideal
  • you can use saran wrap in a pinch but not ideal long term
  • a piece of plexiglass or coroplast is a good cover for the mesh lid
  • hermit crabs are escape artists! Place heavy weights or locks on your lid

Substrate for the tank

  • 6-12 inches deep or 3 times as deep as your largest crab is tall
  • Play sand meant for a sand box is perfect http://amzn.to/1PLQOMu
  • Coco fiber which is shredded coconuts http://amzn.to/1KhJaHb
  • Mix the play sand and coco fiber together, roughly 5 parts DRY sand to 1 part DRY coco

Heat source

Heat mat – We recommend Ultratherm http://amzn.to/2EVPmb2

  • Can be insulated with Reflectix Reflective Roll Insulation http://amzn.to/1PLR1zg
  • Place on the back wall of the tank to provide gradient heat. (Warm and cool zones)

Light source

  • If you have a well lit room that will illuminate the tank during the day you can get by without a lamp. No direct sunlight on the tank.
  • Be aware of how the room temperature rises during summer.
  • They need a normal light/dark 12/12 hour cycle.

Water conditioner

  • We recommend Prime Aquarium Water Conditioner http://amzn.to/1PLRcu9

Ocean Salt Mix

  • Not freshwater aquarium salt!
  • Instant Ocean is the most common brand and is easy to find http://amzn.to/1SrKxnM
  • These other brands are also good and may be available in your particular area:  Fluval Sea Salt, Red Sea Salt, Coralife, Oceanic Sea Salt, Tetra Marine Sea Salt and Marinium.


  • Cheap Tupperware works great!
  • Water dishes should be deep enough for your largest crab to submerge.
  • Provide exit ramps for small crabs


  • If you can afford it, go wireless and digital. WalMart carries digital indoor/outdoor Thermometer Hygrometer You can also buy online. http://amzn.to/1KhJDZM
  • Hygrometers should be calibrated prior to use

Check out this video on how to set up a temporary crabitat in a storage bin: https://youtu.be/x29JaAr9w9U?list=LLCYR6QkuCDm4MJ8hEDeBqvQ.

Bins are not a permanent home, but may be needed in emergencies.

Setting up a Proper Crabitat

Why dry substrate?


How do I create and maintain humidity in my crabitat?
Calibrating your Humidity Gauge

Methods for heating your crabitat
Air Temperature versus Substrate Temperature

Can I Use A Light To Keep Them Warm?
Do I need a light?

Regulation of Crustacean Molting: A Multi-Hormonal System
CrabloverDon on Molting
All about molting
On molting
Is my hermit crab dead or molting?
What is molting?
Pre Molt Symptoms

Dropped or Missing Limbs-
Handicapped/limbless/sick Hermit Crab Care
Why do land hermit crabs drop limbs?
PPS (Post Purchase Stress) Minimizing the Impact

Shell-less Hermit Crab-
My Hermit Crab has left its shell! What do I do?

Growing your own hermit crab food
Going Natural Beginner’s List
Hermit Crab Food Recipes
Hermit Crab Nutrition Table
People food for hermit crabs
Should I feed my crabs meat?
The Power of Protein
What foods are good and bad for hermit crabs?

The importance of the right kind of salt
How do I mix ocean water?
Why can’t I use tap water?

Substrates for Hermit Crabs

How do I choose suitable shells for my hermit crab?
When do hermit crabs change shells?
Painted Shells

Escaped Hermit Crab-
Locating an Escaped Hermit Crab

Cost Cutting-
Cost Cutting Tips
A guide for setting up a large crabitat on a budget

Regulation of Crustacean Molting: A Multi-Hormonal System

The molting cycle in crustacean is controlled by hormones. Below is a snippet from a study on crustacean molting that explains the role of hormones in the molting cycle. Land hermit crabs continue to molt their entire life unlike some other crustaceans.


Coenobita cavipes Surface Molt

Coenobita cavipes Surface Molt

Bodega Marine Laboratory, University of California, P.O. Box 247, Bodega Bay, California 94923

In order to increase in size, arthropods must first molt (shed) their confining exoskeleton. This molting process is under the immediate control of the steroid molting hormone 20-hydroxyecdysone (20-HE).

Read the full article

More articles on molting:
What is molting
Is my hermit crab dead or molting?
Regulation of Crustacean Molting: A Multi-Hormonal System
On molting by Jad Johnson
CrabLoverDon on molting

My crabbing method – Marie

Marie Davis writes about moulting and her crabbing method:

Dry Food Dish

Dry Food Dish

On June 17, 2000, we had the privilege of becoming hermie owners.

My daughters received their first ones as souvenirs from somebody who had visited Ocean City, Maryland. My daughters, nor I, had any idea as to how to care for them properly. For this reason,
I had gone to the library for books to read, to research on the internet, and I asked questions at pet stores. There was information on hermit crab care, and yet so much of it varied depending on
which pet store we visited, which web site we were reading, or what author of which book we were reading. We currently have Ecuadorian, (Coenobita Compressus), Carribbean, (Coenobita Clypeatus), Indo, (Coenobita Brevimanus), Rugs, (Coenobita Rugosus),Strawberry’s (Coenobita Perlatus) and their cheliped measurements range from 1/4 inch to 2 inches. The following is the care we have done with our hermies, and to date have had great success in doing so. Daily they have access to Ethoxyquin free foods that are rotated, (which is an insecticide/pesticide). FMR Treat, Tetra Dried Baby Shrimp, Tetra Freeze Dried Bloodworms, Crushed Oyster Shells, a tad of T-Rex Calsi-sand, Ocean Plankton, Hikari Tubifex Worms, Hikari Daphnia, Flukers Mealworms, Julian Sprung’s Sea Veggies, Hikari Sinking Wafers, Hikari Cichlid Gold, ZooMed Leopard Gecko Food, Zoo Med’s Anole Food, Freeze dried crickets. We call this the dry food dish. In another dish, we offer various fresh foods such as fruits, vegetables, non-sugared cereal, Kaytee Healthy Toppings bird food, (such as mixed nuts, coconut, carrots & greens, apple bits, banana chips, mixed berries, carrots & sweet potatoes, Pumpkin seeds & almonds, etc.), bread, etc. We never offer any citrus foods or dairy products. Even though the hermies have access to the dry foods 24/7, the fresh food dish we offer on a nightly basis before going to bed, and remove it promptly in the morning when we awaken. Within all our main tanks and iso tanks, they have access to a choya log and cork bark which they do munch on. Before their bath, our hermit crabs are also offered out side of their tank in a large Tupperware type container honey, silversides, sardines, etc.

For the water ponds in the hermies tanks, I only use distilled bottle water. I use Instant Ocean for the ocean water pond, and I mix it per the package instructions. I mix a smaller amount to be sure it stays fresh. I use 1/2 cup Instant Ocean, per one U.S. gallon of distilled water. Once it is prepared, I do not offer it to the hermies for at least 24 hours, shaking it numerous times within that 24 hours, and testing the salinity with a hydrometer. Each time it is offered to the hermies, the ocean water container is shaken extremely well. By doing this the ocean salt is distributed evenly, instead of when at the end of the container the hermit crabs get an over dose of ocean salt possibly causing permanent damage to their gills, or other complications.

overhead view of Marie's tank

Overhead view of Marie’s tank

Usually on Sunday, we try to bath our hermies in distilled bottle water. On the non-bath nights, we do mist all of our hermies with distilled water with no additives. After their misting/bath, the hermies get a minimum of at least 30 minutes of exercise in a plastic baby pool that has various climbing objects and tunnels to explore. The substrate in our main tanks and iso’s is CaribSea Aragonite Sand, which is an aquarium safe, dye/color free substrate.

We clean our tanks daily with an aquarium fish net for food and waste materials. We keep our substrate as dry as possible, removing any wet sand at this time. If on rare occasions we have a premolter who wants the sand damp, we will put him in the iso tank so he can make the substrate the way he wants it without disturbing him.

In both our main tanks and iso tanks, I keep the humidity at 75 as much as possible, and the temperature of the substrate at 78-80 degrees on the UTH side of the tank. Our iso tanks are set up as mini main tanks with coral, cholla log, cork bark, fuller rock, huts, dry food dish, ocean and fresh water ponds, etc.

If I find a molter in one of our main tanks, I do remove them and put them into an iso tank if they are done molting. I use my hands, supporting the molter in the palm of my hand, and gently place him on top of his exo while talking to him in a gentle voice that he’s use to. I place a hut over him and I place an oyster shell in the fresh water and ocean water dishes extremely close to the molter so he has easy access to the waters if he wants/needs them. Forty eight hours after molting, I remove him from the iso tank, supporting his weak body and shell at all times, and lightly mist the gill area of his body. After lightly misting the gill area, I gently dab the access mist off the shell if there is any, with a clean paper towel. I then carefully put the molter back into the iso tank with his exo at the opening of his shell and the hut back over him. At this time, I then take the water dishes and oyster shells and replace them with sterilized ones, and wash the water dishes out with hot water. I do this daily, and I do speak softly to the molter as I am doing this. Speaking softly to our hermies is something I do throughout the day while they are in the main tanks and iso’s. When the molter has eaten the softer parts of the exo, I then crush the harder parts of the legs and pincher’s as fine as I can and put them in an oyster shell for them to eat. After 24 hours of the molter munching on the drier parts of the exo, I then make another dry food shell to be put next to the molter’s exo shell. This first shell consists of Dried Baby Shrimp, Ocean Plankton, Krill, crushed powdered oyster shells, Calsi Sand, Boiled Egg Shell, Spirulina, and FMR Treat, etc. I put each food into its own little section of the shell instead of all mixed together.

The day after I offer the above food shell, I then offer all the dry foods the hermies get while they’re in the main tank. Where as I do change the dry food in the main tanks every two days, (unless they get wet before hand), I change the dry food in the iso daily at the time I change the water in the water ponds. Our molters seem to be a little fussy, and seem to eat fresh dry food faster than food that has sat for two days. When the molter is eating well, their coloring has darkened, and is scooting about the iso tank without appearing weak, on the next bath day I bathe the molter with his tank mates so they all smell alike. If he is ready prior to bath day to return to the main tank, I will dip them in the large fresh water pond to rinse the molting odor off of him and to help him smell the same as his tank mates. I check several times to make sure not incidents are occurring upon his re-acquaintance with his tank mates. If he is ready by bath night, once all have had their bath, they have time in the play area to become reacquainted under close supervision. If there are no incidents amongst the hermies, all are returned to the main tank.

Diet and exercise are very important with all creatures to maintain good health. I believe that for a hermie to have a successful molt, he must be in overall good health prior to molting. I attribute their care, diet, and exercise our hermies get prior to molting as important as the care they receive once they molt.

Because of a hermie being so fragile once they molt, I believe their gills are even more sensitive than usual. This is why I lightly mist the gill area 48 hours after they molt to keep them moist. Because of our daily handling the hermies with mists or baths, and also handling a few other times during the day, our hermies aren’t threatened when handled after they molt. In fact, the first time our molter is picked up 48 hours after they molt, they happily come partially out of their shell to great the misting of their gills. I attribute all the care given mentioned in this article as to why I have such a high successful molter rate.

Clive looks dead - Marie Davis

Clive looks dead – Marie Davis

Clive shrunk-Marie Davis

Clive shrunk-Marie Davis

Clives tucked within shell-Marie Davis

Clives tucked within shell-Marie Davis

CrabloverDon on Molting

This is a collection of posts from CLD from 1999. While not all of the information in these posts is still considered accurate it is worth reading as Don was a important part of hermit crab care development.

Archives from the Hermies Yahoo!Groups that Don once Co-moderated with Jennifer Borgesen and Vanessa Pike-Russell.

Hermies Yahoo!Groups MESSAGE 298
Date: Thu Nov 4, 1999 8:40pm
Subject: Molting worries…..wet/dry substrate

Folks may I suggest that you read up on all that you can find on molting…there are really no black and white ‘textbook procedures’… but some very enlightening observations out there. There are no set/exact time tables or time lines for the molting process. Molts are individually determined by the crabs need to regenerate appendages or for their natural ‘growth’ process… Here at Kritterlandusa, we have molters year round and each molt, while similar, cannot be determined as to how long the process may take… or how long the crab will take to’bounce’ back.

Some smaller crabs MAY molt often while the larger guys might not molt for a year or two. So please don’t sit with watch… waiting for it to happen…because you heard there is a ‘season’or that you had that crab for this or that period of time! Folks, it ‘ain’t’ that simple! Nature knows best and when the time comes, it comes! Nature by design of the shell as a home and the crabs ‘soft tissued underbelly’ has a purpose here. Prior to a molt, crabs store extra water within their shells to help with that extra hydration needed for them to shed their old exoskeleton in the molt process. Contrary to popular myth, most hermit crabs do not molt OUTSIDE of their shell and many do not go under the substrate to molt.


molting is very stressful for the crab at this time… their new exoskelton must harden as they are very vunerable at this point. As little disruption as possible is necessary, thus it is recommended that you isolate the molter from the others by blocking off an area of isolation for him or transporting others to another area so he is not disturbed. The more secure he feels the more readily he will be up and about quicker. Never dig a molter up … when isolating a molter have a small amount of food available and a small shell of water close by IF they so desire to partake. (I use a half-dollar size clam shell with a snip off a sea sponge for the water source ….) The worst thing you can do it start wetting the sand around him! Bacterial growths harm a molting crab as often as a ‘bad molt’… as they cause additional stress to the already stressed molter… a drier and warmer area of choice is usually better… If you have any questions about how to prepare FOR a molt, do it ahead of time. Call or e-mail FMR for other particulars…. READ comments on other sites… Before you decide that you HAVE to do this or that, CALL FMR for advice…PLEASE, do not take it upon yourself to decide to soak them,because you think….often, what one mightfeel is necessary is often not the best for your crabs, etc. …in cases that the unusual happens Kathy at FMR can help you determine what action to take.

Folks, if you have several ‘diggers’ at one time, it is possible that they are looking for a more desirable temperature….and are NOT ‘ready’ to molt.

Their crabitat may be too warm or cool. Remember the goal is to MAINTAIN a constant temperature range… not ‘jumping to a too warm to cold environment…(see heating tips, etc. that were previously posted as they can apply here…… Sorry, Cindy, I know you don’t like to have to go back through previous post, but there is some good advice there) There are tell-tale signs that usually signal an oncoming molt…. such as: less antennae activity, dull-look of their eyes (like a cataract on a human); behaviorial change…and seeing them in or near the water dish more than usual.

Crabs also love to burrow for this purpose. Some just dig to entertain themselves… ‘sneaking’ up at night… to eat and drink.

Hope some of this helps…..

Happy Crabbing!


Hermies Yahoo!Groups Message 527
Date: Sat Nov 27, 1999 9:55pm
Subject: Re: my molting crab plus a little more…
…in this past week, I had four different people mail me saying that they lost their molters do to TOO MUCH moisture. The problem lies in the fact that people tend to do TOO MUCH after the molt begins.

By nature, a crab will store extra moisture/water inside of their shell PRIOR to their molt…in order to expand and explode the exo skeleton. Usually enough moisture is retained to allow their new exo to harden… too much moisture can cause their newly developing limbs to actually become too hydrated and in some cases fall off. Like in pre-natal care for women, pre-molt care is just as important in our guys… Those Stresscoat baths, extra calcium… and plenty of fresh dechlorinated drinking water… prepare and ‘set them up’ for a better and easier molt. That is often all that is needed… until ‘that time.’

Nature normally takes over and most of the time all goes very well. They do need a quiet,place to be left undisturbed and free from outside stress for a few days until THEY are ready to take on the world! We have had many great above the substrate molts here at

Kritterland with two hundred-fifty plus guys…. Eight are doing their ‘thing’ right now…. I do keep a slightly damp sponge (in a clam shell in the iso tank…) for the fact that one of the fellows might decide to visit for a ‘drink’ or some extra moisture.

The smaller guys often find solace in the entrance of a larger unoccupied shell… which makes a quick check easier… trying not to bother them anymore than necessary. I often use an eye-dropper to drop a drop or two of the ‘treated’ water in the larger shell.

Remember this is for ABOVE molters…. It is not a good thing to go digging up those guys who are UNDER the substrate… more than often people want to go this, but more harm is done than good. I do believe in allowing nature to take its course. I have to…

If I only had a couple of guys to care for, it might be different. I have never had any bacterial problems and few bad molts with my guys since using these methods and keeping the substrate dry. A bacterial outbreak would be disastrous for us.

Again, whenever I have a doubt, I call Kathy at FMR. There are situations that might call for special attention, but through updated info and research, the advice I try to pass along is from the heart and from ‘tried and true’ knowledge. When ever in doubt of doing something, do as I do…. CALL KATHY!!!!

(Remember it was pointed out that some of the info in the FMR FAQ section is outdated and because of some tech difficulties they have been unable to get into it to update some info. Hopefully, this will soon be updated and corrected….The care sheet and health tips are up to date.)

As one becomes a more seasoned crabber they will find methods, etc. that may work better for THEIR situation, but for the newer crabber I would rather present and share the basics with you…. and take a safer route so that your earlier days of crabbing might be smoother ‘sailing’ than full of heartache in trying out all that you may have heard.

You will soon ‘learn’ your crabs and realize those guys that want thta ‘extra’ attention and the ones who just want to be left alone… The more you handle them and let them get more accustom to your ‘smell’, ‘feel’ and ‘voice’ through this interaction the more apt you will be in learning their individual demeanor and ‘personalities’… Try ‘hand-feeding that little shy guy…. or a ‘spritz of a mist’ will often bring a fellow out…. there are those who are recalcitrant who will ‘out sit’ you…. but don’t give up… they, too, will come around!

Good Luck, Thanks and Happy Crabbing!


Hermies Yahoo!Groups Message 592
Date: Sat Dec 4, 1999 1:20pm
Subject: Re: missing limb question

That little ‘dab’ of ‘gel’ is the ‘regeneration’ of his missing leg… before long that leg will be back!

The new leg will be smaller than the lost leg, but don’t worry later molts will allow a ‘catch-up’. As for the other fellow , he, too, will regenerate that feeder claw… in due time. Some crabs are said to be ‘thrown’ into a regrowth with the loss of a leg, others will regenerate the missing claw/leg when nature takes its course. Good Luck and Happy Crabbing! All will be well…. CLD

Hermies Yahoo!Groups Message 668
Date: Thu Dec 16, 1999 1:27pm
Subject: Re: Exo Question

Q. What do you-all do with the left over bits of exo?

A. I used to ‘save’ it… but no one really seemed to interested as you mentioned. So now I usually just ‘pitch’ it out… Have had a couple of thoe quick re-bounders, but I think that it might just be ‘in their constitution’… I was once told that the guys ignore the exo after a period of time as it dries out only ‘chowing down’ on it while still a freshly molted material… but with these little guys, who knows!

Happy Crabbing!


Hermies Yahoo!Groups Message 670
Date: Thu Dec 16, 1999 2:40pm
Subject: Re: Question about exoskeleton…

Q. You stated that the crabs don’t like dried out exoskeletons. My crab molted overnight but has not eaten any of his old exoskeleton (at least as far as I can tell). Is this bad news for the molter? You have me really worried now. A little reassurance would be helpful right now. Should I pick up the molter’s shell and make sure he is still alive.

A. What I said was: “I was once told that the guys ignore the exo after a period of time as it dries out only ‘chowing down’ on it while still a freshly molted material…” This comment was made in reference of ‘saving’ old exoskeletons… a person mentioned they couldn’t understand why their crabs didn’t eat the others discarded exokeletons that she had been saving for a period of time. You have to remember that the old exo basically is shed from water pressure ‘popping’ the old away from the new… ‘freshly’ as opposed to dried out (which would take several days to dry out under normal conditions… not unlike the shell of a shrimp)

In a regular molt, it often takes days for a crab to regain the energy to eat away on his exo … most of mine do this… but there are those few exceptions ….like Jenn mentioned… I have had several of my “E’s” up and around before I realized that they had even molted. It depends on the individual crab. There is no need for you to worry. You have to be patient with a molt… few are exactly alike. The best advice I can offer to you is allow the fella to rest… Too much “handling and checking on” a new molter is quite stressful. Give him a few days… Many times, they are eating away on the softer parts of the exo and working their way out to the rest of it. Many of my guys eat ONLY what they want to eat… leaving the majority of the discarded claws and legs… and all have done very well. Just let nature takes its course

… I know that the desire/temptation to peek is overwhelming, but this is a great first and hopefully a new start for you and your guys… you don’t want to *jinx* it with worry! Good Luck and Happy Crabbing!


Hermies Yahoo!Groups Message 678
Date: Fri Dec 17, 1999 9:50am
Subject: Re: My first moult

Q. My molter is has eaten his exoskeleton (after all my worrying!). He is now sitting with his legs showing outside his shell. Does this mean he is ready to rejoin the colony (means taking his iso unit off of him)?

A. It is usually a good idea to wait about a week or so before you reintroduce them back into the fold… if you are ‘familiar’ with the crabs ‘personality’ you can gauge their activity level pre and after molt… and determine when to return them. Again each crab does bounce back at their own rate of speed and nothing is writing in stone. The basic rule of thumb though is about a week to ten days after the molt… but that is only a guideline. How this helps some…
Hermies Yahoo!Groups Message 717

Date: Thu Dec 23, 1999 11:02am
Subject: Re: Molting Question…

Q. Another one of my crabs has molted! He was missing one leg, which grew back to almost normal size. But now he’s missing another leg! I guess he lost it in the molt. Is this normal?

A. As far as losing legs during (or right after) a molt… It is not what I would call ‘normal’, but it often happens. There are probably many reasons for this additional loss… but many times, it appears that the little fella could not shed that ‘one little piece’ of their old exoskeleton… and they will damage leg or claw trying to get off completely…

Also, the ‘new’ exo is usually quite delicate and can break off easily… Another reason to allow them to rest as much as possible … Some guys will try to do more than they are capable of doing… others will take their time in recovery from a molt… another one of those nature/ personality things!

It seldom affects them… if this is the case. Those legs will regenerate and come back as did the one your guy previously lost. Now, if he continues to lose legs or a claw, this is the time to ‘worry’

Hermies Yahoo!Groups Message 774
Date: Sun Jan 2, 2000 6:06pm
Subject: Re: Moulting inactivity

Q. Is a total lack of movement normal for this length of time?

A. molt is extremely stressful to our guys…and the ‘rest’ that follows is to allow them to regain their ‘energy/strength’ and for their new exo to ‘harden’… Size usually plays a big role in the ‘bounceback’ period! For some smaller guys who molt more often, they as usually less stressed… but the larger guys who might be a year or two between molts, often have a rougher time. Of course, there are those many exceptions… the best advice is to allow nature to take its course at that point! If a crab had a good ‘storage’ of moisture already within his shell, and the exo to munch on, then he might not be ‘moving’ around too much. I have a friend who had a jumbo “E” that was down for over six weeks molting… and one person I know of had a fella down for two months! On an average a couple of weeks can be expected for a medium/large guy for a ‘normal’ molt… but that is a ‘ballpark’ figure. I have had teeny guys ready to rumble in a couple of days… and others a week or so… it really does depend on the individual conditions and demeanor of your fella.

Q. I am concerned about the lack of moisture and run a humidifier for an hour twice a day. There is NEVER condensation on the inside of the cage and the humidity level doesn’t seem to get above 40%. Does anyone ever run a humidifier under careful watch?

I’ve never thought of running a humidifier? The only concern I would see with running one would be what water to use in it.

Brenda is right, you would need to be concerned about the water… but personally, I would like to see you attempt to use the sponge in water/undertank heater method of creating humidity. There has been some ‘debate’ about using a regular humidifier with the guys. PLUS you really want to MAINTAIN a pretty good level of humidity at all times…. so your method would have its pitfalls. The humidity level, like the temp level really needs to be measured at the substrate level since that is where your guys spend most of their time… The sponge method has worked quite well for many folks… You might want to check out some of the posts in the message archives relating to it.

Q. On an unrelated item, I’ve noticed CLD talk about a 5 gallon ISO tank. How does one “move” a moulting crab to ISO?

A. Each bath day, I play with and ‘check out’ EACH of my babies! I look for various signs of molt or other possible problems. IF a fellow is sluggish or shows some indication of a molt, then he will be placed in one of the several heated iso tanks for closer observation. But, many of these fellas have surprised me and ‘up and molted’ without warning!

With these fellows I use dividers to build an area around then for a little protection. It is best not to disturb a molter… and if you must it should be kept to a minimum of time. Most of my guys have molted above the substrate… and a couple of times it was necessary for me to transport a fella to a separate iso unit…. I used a regular spoon and gently lifted the guy, exo and all, at one time…and gently placed him in the iso tank. I prefer to use a dividing area in the main tanks for this, but there are those times… and I always have at least one of the iso tanks set up, properly heated and with acceptable humidity… as a big fluctuation of temps might do more harm than good. If the main tank is already consistant heat wise you are far better off in using dividers for your fella (also, some great suggestions in the archives on this too!)

Q. I hate to disturb Spray , the little guy, but in changing his water yesterday accidently touched him and there was 0 response. I’m tempted to do something more drastic to see if he’s still alive. I picked up Hypie and checked on him evey other day. As long as you don’t bother him too much I don’t think it would hurt to check him. From what I gather if he had died you would know by a fishy smell. Hopefully he is alright. He may just need some extra time to rest up.

A. I fully agree… You will KNOW if he really passed on, from THAT SMELL! If you do decide to ‘check on SPRAY, do keep it to a bare minimum… A fella in this stage of molt is so vulnerable and really requires some time to regain energy…You really don’t want to create any further stress by picking him up and handling him too much… he might relate the intrusion as a possible predator or feel that you expect him to ‘show himself’ and entertain you… warmth, moisture and quiet are several keys to a better molt experience for most guys.

Hermies Yahoo!Groups Message 778
Date: Mon Jan 3, 2000 8:43am
Subject: Re: a molt

Q. — “Jad B. Johnson” Jad@a… wrote:

Well, I got back from a week long stint in Tampa Bay for the Outback Bowl (Go Dawgs!) around 2:00 am last night, and Red had molted. I’m very concerned and would appreciate advice and prayers. When I saw the bits strewn about I panicked. I didn’t know how long he had been like that. I have only had one successful molt, so I immediately thought that he was dead. I threw away the exo and pulled the body out of the shell. There was no “dead smell” but I thought that he maybe had just died and hadn’t developed it yet. It was then that I felt a tiny bit of movement. I got the 1 gal. ISO tank put shells and water in it and got the exo out of the trash (it was on top and still clean). Finally I draped a towel over it. I checked on him this morning and he was moving. I can’t tell you how happy I am, but I am also still quite worried. Do you all think that the time I held him in my hand and sprayed him with water “stressed” him out too much. Is ok it to dunk him in stress coat solution or is it too late, or maybe be better to mist him with SC? I have a 1 and 2 record with molts. Any reassurance will be appreciated. Thanks. Jad

A. The BEST thing you can do for him at this point is to leave him alone! No dips, no more mistings… He is probably already at the highest stress point and if he makes it through everything he needs to be left alone so he can start to regain some energy and to allow the new exo to harden. made sure the area you have him in is warm, and quiet…away from activity, etc. Place a dampen sponge close by incase he needs it. Check in on him PERIODICALLY by looking but I would refrain from anymore ‘handling’… this could cause him a great deal of damage and/or stress…that he might be unable to handle in his present condition.

By ‘pulling’ his little body out of his shell, there may have been some damage to his delicate exo… not to mentioned additional stress. The fact that he is showing a little movement is promising…. If you MUST transport him, carefully/gently use a spoon to ‘lift’ him, shell, exo and all to place him gently/carefully into the new place…

If you need to, e-mail me direct! Good Luck and keep us posted! CLD

Hermies Yahoo!Groups Message 831
Date: Sat Jan 15, 2000 1:15pm
Subject: Re: Kosh update

…My teeny and small guys usually bounce back very quickly! I do wait a couple of days after I notice the activity in the iso before returning them to the fold. With just getting the three new guys, it might be best to hold off a couple of days…

Intros at bathtime is also a great idea… neutral territory! Wish you luck with all your guys Delenn won’t know what to do with all the company! Congrats! To you as Crabmom and to KOSH the successful molter!

Happy Crabbing! Don

Hermies Yahoo!Groups Message 859
Date: Thu Jan 20, 2000 7:18pm
Subject: Re: Twins, Triplets and plexiglas…..

Vanessa and Christa:

We have several sets of twins too! Plus a set of triplets to boot! TWEEDLE DEE–TWEEDLE DUM, ME and (my) SHADOW… SPECK and SPOT… DASH and DOT… are a few of our little ‘twin’ sets! SAM and SAM TING and HIM TOO are the triplets….(S.T. in honor of Christa’s SAM TING) All of our multiples are little hyperactive Ecuadorians.

Christa… about the plexiglas thing! You already know that I use plexiglas for setting up my iso areas within a tank…and why I find it better for my molters. It really is easier in the cooler months to assure that the temperature and humidity levels are more consistent, just being able to set aside an area for a molter or two. May I offer a better alternative to a tank divider (which I bought, but seldom used) It is to buy a sheet of clear Plexiglas and have it cut so you can create the area that you want to cordon off. Most craft stores and many frame shops sell it… or you can get a sheet at a place like Home Depot… (they usually sell it to replace glass in windows…and most places will cut it to your specifications) Using some clear bookmakers tape or adhesive tape, you can connect these pieces to ‘fit’ corners, “free standing” areas… really any number of unlimited configurations…

Even though I have several iso tanks set up and ready to go I do prefer to have the guys ‘closer’ to their buddies during this time. Last week when my little BARNEY started to act odd, I ‘fixed’ him a corner of one of the main tanks just ‘in case’… then I actually saw him shimmy out of his exoskeleton! He was not himself at bath time, but other than that he showed little indication that he was about to molt..

However, a few minutes later, right before my eyes, that little guy popped his exo and like you or I might take a turtleneck sweater off… he slid ‘out of’ that old exo… he wagged his antennae and retreated back into his shell…staying pretty much ‘dormant’ for a couple of days… I had witnessed a few other molts, but none so quick and easy as he did it! He is up and around some… enjoying ‘his’ sponge…I had a small piece of sponge that I keep wet for the molters… his ‘exo’ long gone… his coloring is starting to come back some…at least it’s not Mary Kay pink anymore!

Several of his buddies sat outside the plexiglas wall looking in on him. As odd as it may sound, these guys seem to sense when one of their own is ‘down’… He had a ‘buddy’ in with him who also decided to ‘do the molt thing’ that same evening… LITTLE BUD was already ‘blocked’ off in another tank, but I decided to put he and BARNEY together… I used a mirror on one side (so I could observe them and not disturb them during this time… WORKS great!!!) and the plexiglas on the other sides. It was so cute to see their buddies and well-wishers looking in on their ‘downed comrades’! Several of them kept a vigil right there against the ‘wall’ looking in on their buddies. This was the second molt for “LITTLE BUD”, but the first for dear little “BARNEY”. … Both fella did well and are up and around but not quite ready to return to the ‘flock.’ Am anxious to have both of them out and about with the group real soon! “BARN” is one of the resident characters in his tank… Plus he loves Bath Day… Where he can play with/in the fresh fruit and then ‘swim’ and play!

Have six molters in various stages of molt as I type… What FUN! One of our big boys surprised us with a molt earlier in the week and he is doing great!
I am glad he just went on and surprised us… as I still worry when my larger fellas get ready to molt…
If you decide on the ‘section’ thing, let me know and I will be more than happy to explain it further…

Happy Crabbing!

Hermies Yahoo!Groups Message 902
Date: Thu Feb 3, 2000 9:02am
Subject: Re: Jumbo Molt

Q. — tbean tbean@a… wrote:


A few days ago, our biggest –Hercules, molted without warning. He is a jumbo about the size of a fist. His eyes had been looking a litttle paler than usual, but I had no idea it would be so sudden (esp. after it took Neville 4 months to molt after his eyes went pale). He molted in one piece and is still alive. My concern is that he isn’t eating his exo. It has been about 5 days now, and he hasn’t moved or touched the exo. I am thinking he just needs to rest some more, but is it normal for a big guy to wait this long before eating? Thanks for the info., and I am really sorry to hear about all the crab deaths recently.

A. It has been my experience that the bigger guys do take a great deal longer to bounce back after shedding their exo. Give HERCULES a few more days to see if he starts eating his exo. Some of my bigger molters, have actually left some of the exo uneaten… especially the large claw which seems to be stronger and probably less tasty than the other parts! I would not worry unless you begin to smell THAT smell! Congrats to you and HERCULES!!!! Don’t you love those ‘unexpected’ molts… less tension on the caretaker… Wish all my guys would ‘surprise’ me! Good Luck and Happy Crabbing!


Hermies Yahoo!Groups Message 1085
Date: Wed Mar 8, 2000 11:55am
Subject: Re: about Molting/ …a tad to add…..

Just a little more insight into the process…. “Kritterland” uses tiny ‘riverrock’ substrate and most of my guys are ‘above molters’… and like Jenn’s mine do love those larger shell “molting shelters”!

The ‘process’ of molting does include that ‘water build-up’/’burst that exoskeleton thing’ as Jenn mentioned… The split begins around the abdomen, and those who have witnessed an actual molt in progress can tell you how fascinating it is to watch the crab ‘shimmy’ out of the old exoskeleton. I can only describe it as a person ‘pulling’ a turtleneck sweater over their head…

I have read and been told that there is a ‘natural’ secretion produced during this time that enables the fellas to shed their old exoskeleton more easily… leave it to nature! Too bad that all molts are not as successful as others allowing them to slip totally out of the old exo EACH time… While the ‘stresscoat baths’ have not ‘solved’ all the problems with often less successful molts of the Compressus, “E”, species, it does seem to have a positive effect on helping them get through more molts.

The new molter will look, actually is, smaller until the process of the hardening of the exo takes place… water and air will cause the body to swell… forcing it to grow larger in time.

More articles on molting:
What is molting
Is my hermit crab dead or molting?
Regulation of Crustacean Molting: A Multi-Hormonal System
On molting by Jad Johnson
All about molting by Lisa Loeske

All about molting

Originally written by Lisa Loseke 2003

The molting process is a central, and nearly continuous, part of a crab’s life. A crab may spend 90% of its time getting ready to molt, molting, or recovering from a molt. There are many dangers to molting including predation, difficulty in movement as muscles have no ridged points of attachment, desiccation, and the risk of an unsuccessful attempt to exit the old exoskeleton. Eighty to 90% of arthropod deaths are related to molting.

The Molt Cycle

There are four phases of the molt cycle: intermolt, premolt, molt, and postmolt. During the intermolt, the exoskeleton is fully formed and the animal accumulates calcium and energy stores. It is the longest phase and constitutes the time between molts.

Premolt starts when the old exoskeleton begins to separate from the epidermis (skin), and the new exoskeleton begins to form below. Calcium and other nutrient are reabsorbed from the old exoskeleton at this time and stored in the tissue of the crab. This serves the dual purpose of softening the old exoskeleton and recycling the calcium for the new exoskeleton. The muscles in the pinchers and limbs then shrink in anticipation for when they are to be pulled out of the narrow joints of the old exoskeleton during the molt.

Molting occurs as the old exoskeleton cracks and the crab pulls out of it backwards. The new exoskeleton continues to form and is pale and soft. Bloating with water is responsible for the increase in size after a molt. In the case of land crabs who may not have access to water directly after molting, this water comes either from the shell water (which they carry around with them in their shell), and/or from water accumulated in the blood and water sacs during preecdysis. This water pressure is used to stretch the new soft exoskeleton into a larger form. After some rest, the crab eats its old exoskeleton as a source of calcium and other nutrients.

Postmolt occurs as the new exoskeleton hardens through the two processes of sclerotization (tanning) and calcification. Sclerotization is the chemical process where proteins form chemical bonds between each other to form a more rigid structure. Calcification is the process of putting calcium into the exoskeleton. Also in this phase the muscles grow back to their natural size and the excess water is lost, leaving room for further growth throughout the intermolt.

Feredir, just after molting. Feredir has regained his color

Feredir, just after molting. Feredir has regained his color

The Importance of Water

Because water pressure is the driving force behind the expansion of the new exoskeleton, it is very important that hermit crabs live in a very humid environment and have access to water that is deep enough to fill their shells. Also, hermit crabs make their blood saltier during a molt to have the water gain necessary for the expansion. Thus a salt water pond is essential for the regulation of this process as well.


Ruppert E. E. and Barnes. 1994. Invertebrate Zoology 6th ed. Saunders College Publishing, Philadelphia.
Stevenson J. R. 1985. Dynamics of the Integument. Pp. 2-43 in D. E. Bliss and L. H. Mantel. The Biology of Crustacea Vol. 9: Integument, Pigments, and Hormonal Processes. Academic Press, Inc. New York.

More articles on molting:
What is molting
Is my hermit crab dead or molting?
Regulation of Crustacean Molting: A Multi-Hormonal System
On molting by Jad Johnson
CrabLoverDon on molting

On molting

Please note this article is old and some of the information may be outdated.

Originally written by Jad Johnson 2003

Perhaps the most traumatic event in the life of your crab, not to mention the trauma for the owner, is a molt. Often for me it begins by checking on my guys in the morning (I find that they like to do it during the night). A momentary flood of panic washes over me when I see crab bits strewn around the Crabarium. “Oh, no. Has he been mutilated, or is he ill?” Then as I realize I have a molter on my hands, I REALLY begin to panic!

Molting (or moulting to our Aussie buddies) is the natural process by which your crab grows. Like all arthropods, they have a hard exoskeleton, or outer shell which does not grow. So about once a year, depending on the size, age, and eating habits of the crab, they will shed their “exo” to complete the growth process. They will also take this opportunity to re-grow any limbs lost or damaged after the previous molt. “But Jad,” you ask, “is there anything I can do to help my little guy out?” I’m glad you asked.

There are some tried and true methods, and then there are more experimental ones. In this article, I’ll deal with standard methods, and will leave cutting edge advances to another day. I will also focus on the above substrate molt. Probably about 95% of my guys molt on the surface. Let’s examine the molting process in segments:

The Pre Molt

If you’re going to help your crab prepare for a molt, you’ll need to know what to look for, right? There are several telltale signs. Some of the more common are: cloudy eyes (like cataracts); slow and lethargic movement; hanging out on the sponge, in the waterdish, or other damp locale; digging in a wetting the sand, and the appearance of gel limbs, if the crab has any missing claws or legs.

Gel limbs are proto-limbs, buds that are the beginning of appendages that were lost previously. They appear well before a molt, but get larger and often darken as the molt nears.
Many land hermit crab owners like to isolate their crabs at these first warning signs. I usually don’t, because when I do, my crabs stay in a little one-gallon critter keeper for three weeks without molting. Of course, when I replace them back in the tank they molt immediately. Usually, I wait until the deed is done before transferring them to an iso tank. My iso tank is about a half-gallon, and I keep it inside my main tank. It is easier to control the humidity and temperature levels this way.

During this pre-molt time, there are a few things you can do to help: Pre-molt baths in water treated with Stress Coat by Aquarium Pharmaceuticals is helpful and practiced by most crabbers. Some more advanced methods include giving your crab honey or Gatorade to give them that little sugar rush to help them increase energy. Some advocate applying natural aloe to parts of their exo. This helps soften the exo.

During the Molt

Not a whole lot to do here. just sit and watch. It is important not to disturb them during the actual even. If possible keep the environment warm, humid, and dark.

Post Molt

Congratulations! The molt is over.. You’re about halfway there. This is often the hardest period for them to get through. If you had just spent several hours sloughing your skin, I bet you’d be exhausted, too! Unfortunately, everything might seem to go right, but the crab still may not make it through this critical time. To help increase your crab’s chances of success, consider these tips:

  • At this point, the crab should definitely be isolated. His soft pink exo is vulnerable to nefarious crustaceans. If you haven’t already done so, GENTLY transfer him to a spare tank, or an iso unit. Some people will take a section of a 2-liter soda bottle with the top and bottom removed to instantly section the crab off with out moving him.
  • Like any other traumatic medical procedure, what the patient needs most is peace and quiet. Try not to handle the crab at this point unless it is absolutely necessary! Too much activity at this point can result in limb damage or loss, and stress to the crab.
  • Be sure to keep the crab’s old exo to munch on. This helps replenish the calcium lost in the molt. I will usually save the uneaten portions of the exo for later molters. If the exo has already been ravaged by Crabarium-mates, then cuttlebone or sterilized eggshells will do.
  • If the iso unit the crab is in is dry, you may want to mist your lil’ guy, because humidity is also important at this time. Remember not to overdo it; a gentle spritz is all it takes. A nearby damp sponge will also help.

After about a week or so, the patient will be ready to rejoin society. Most of the exo will have been consumed; generally the tough leg tips and large feeder claw will be all that remains. At this time your hermit might want to slip into something more comfortable- a bigger shell. Be sure there are several to choose from. Of course, he may like the one he’s already in, thank you very much. They’re so picky about their shells, aren’t they?
For them, it’s exhausting, and for us it’s nerve-wracking. Either way, it ain’t fun. However, your crab’s molt need not be a death sentence. With a little preparation and TLC, both you and your crab will get through it fine. It just takes a little practice and a lot of patience. Pretty soon, you will both be old hats at it. You’ll be calm and reserved. until the next molt begins, then it’s panic city all over again. Oh, Well.

Copyright 2003 Jad Johnson. All Rights Reserved

More articles on molting:
What is molting
Is my hermit crab dead or molting?
Regulation of Crustacean Molting: A Multi-Hormonal System
All about molting by Lisa Loeske
CrabLoverDon on molting

FAQ Is my hermit crab dead or molting?

Originally written by Marie Davis

Double check that shell for a stealth molter!

FAQ Is my hermit crab dead or molting? Photo credit Stacy Griffith

Is my hermit crab molting or dead?

It is often extremely difficult to distinguish whether a hermit crab is indeed molting, or has passed over the Rainbow Bridge. This is due to how similar in appearance the two can be. The approach a hermit crab owner takes can mean the difference between life or death if the crab is molting. I have witnessed numerous land hermit crabs during the molting process and identified four main molting positions.

The most common position begins with the hermit crab lying down on their side while shedding their old exoskeleton. The eyestalks are in a laid down position, antenna appear to be tucked under their eyestalks between the large cheliped and feeding claw in a downward position. The legs appear to be lifeless and very limp with a slight curl. When they lie on their side and are ready to shed their exoskeleton, they come most of the way out of their shells, only keeping the very tip of their tail within the shell. At this time, the hermit crab appears to be lifeless. If one watches long enough and very closely, they will see the hermit crab do an occasional very slight jerk of a body part and a very slight wiggle as they begin to loosen their old exo from the new exo. In between these slight jerks and wiggles, the hermit crab lies extremely still and appears dead, with a very slight occasional movement about their gill area as they take a breath to be able to continue with the deed they must complete. Once the old exo is loosened from the new, the little jerks and wiggles they do are slightly more noticeable. A brownish/brownish orangey fluid appears as the old exo splits, and the hermit crab begins the removal of it. If the hermit crab’s old exo is darker in coloring, it resembles a bubble like appearance going through the old exo as the hermit crab removes each part of his new body from it.

Another popular molting position I have observed is that of the hunched hermit crab. Instead of lying down, they are upright in their shell. All of the above observations apply, only the position is different. The molter comes out of their shell to where their first sets of little legs are. As they begin their molting process, they are in the hunched back position. Again, they are very still and appear dead during the molting process while in this position.

On a few occasions, I have witnessed hermit crabs molting while in a sitting up position. By this, I mean the opening of the shell is facing straight in an outward position. The hermit crabs legs, pinchers, and head appear to dangle out of the shell. The eyestalks, antennas, and limp legs, etc. are all observed in the same manner as mentioned in the first paragraph while the hermit crab molts in this position also.

On one occasion, I had the pleasure of witnessing a hermit crab molting upside down. The only thing I could see were her limp legs partially out of the shell as she molted, and the bubble-like appearance as she loosened and removed her old exoskeleton from her legs and pinchers.

The appearance of a hermit crab in the process of molting can be similar to that of one that may have passed over the Rainbow Bridge. If unfortunately the hermit crab has passed on, there is not much a crabber can do for him except to bury him. If the hermit crab is indeed molting, disturbing the hermit crab at such a fragile and critical time of their life could mean death to that molter.

If one does find a hermit crab in any of the positions I mentioned above, (or any other position), and you are curious as to whether the hermit crab has died or is molting it is always best to play it safe and act as though the hermit crab is molting. If he is in isolation, do not disturb him in any way. If he is found in the main Crabitat where there are other tank mates within it, push a cut two liter soda bottle around the hermit crab to the bottom of the tank, and remove all climbable objects away from it so the others cannot disturb him. Leave him be. One must have patience when this questionable situation arises. This is a very critical time in your hermit crabs life that only you can make the difference as to their life or death by the action you take when you first notice them.

Sierra appears dead by Connie

Sierra appears dead by Connie

Sierra freshly molted by Connie

Sierra freshly molted by Connie

Photo Credit: Connie (aka sierracc), Stacy Griffith (Daethian)

More articles on molting:
What is molting
Regulation of Crustacean Molting: A Multi-Hormonal System
On molting by Jad Johnson
All about molting by Lisa Loeske
CrabLoverDon on molting

FAQ What is molting?

Orginally written by Vanessa Pike-Russell

Arthropods (e.g., insects and crustaceans) must molt their exoskeletons periodically in order to grow; in this process the inner layers of the old cuticle are digested by a molting fluid secreted by the epidermal cells, the animal emerges from the old covering, and the new cuticle hardens.


The growth cycle of a land hermit crab is based on a process known as molting (or molting), often triggered by the amount a hermit crab eats and drinks. Hermit crabs have rigid exoskeleton which cover the eyes, claws (chelipeds), legs (peripods) and parts of the shield and posterior carapace. These areas do not grow as the crab grows, and need to be shed.

A hermit crab will shed their exoskeleton when it becomes too snug about their growing body. Hermit crabs cannot go shopping for new skin, they instead shed their exoskeleton and build up the tender tissues with fluids and with the help of chitin, they develop a hardened exoskeleton. To be able to do this, your hermit crab will need a lot of moisture. You might find your crab near the water dish a lot prior to a molt. If you were to watch your crab molt, you would see your crab stretch and twist until the exoskeleton splits, then slips out of it like a suit. Some crabs cannot do this in one piece, so you may see legs and claws strewn about.

Shed Exoskeleton of Coenobita Clypeatus

FAQ What is molting? Photo Credit Carol Ormes Shed Exoskeleton of Coenobita Clypeatus

Molted Exoskeleton of Crab Kate, one of two land hermit crabs owned by Carol of CrabWorks. Images used with permission.Copyright 1999-2005 Carol of CrabWorks

Once your crab has slipped free of that constricting exoskeleton they will either retreat into the safety of a large shell or bury down into the sand or other fine substrate to hide away for a time. There are some cases where a hermit crab would do neither of these and choose to moult above the substrate and is visible throughout the moulting period. It all depends on the crab and how safe he feels within his crabarium and the type of substrate offered.

Arthropods molt periodically in order to grow and mature. Triggered by hormones released when its growth reaches the physical limits of itsexoskeleton, the molting begins (apolysis) when the cuticle separates from the epidermis due to the secretion of a molting fluid into the exuvial (cast-off skin or cuticle) space. The endocuticle (chitinous inner layer of the cuticle) is then reabsorbed and a new epicuticle (outer, shiny or waxy layer) secreted. Ecdysis is the act of shedding whatever remains of the old cuticle.

Step 1: Apolysis — separation of old exoskeleton from epidermis
Step 2: Secretion of inactive molting fluid by epidermis
Step 3: Production of cuticulin layer for new exoskeleton
Step 4: Activation of molting fluid
Step 5: Digestion and absorption of old endocuticle
Step 6: Epidermis secretes new procuticle
Step 7: Ecdysis — shedding the old exo- and epicuticle
Step 8: Expansion of new integument(covering or investing layer)
Step 9: Tanning — sclerotization(The hardening and darkening processes in the cuticle (involves the epicuticle and exocuticle with a substance called sclerotin) of new exocuticle. Now the chitin and protein are laid down and the exoskeleton will become hardened and shiny after a few weeks like Wumba in these post-molt photos.

Wumba’s molting photos:

This photo depicts a freshly molted crab having just pulled free from it’s shed exo:

Sierra freshly molted by Jen Stedner

Sierra freshly molted by Caroline

One this painful part of the process is over, your crab will now need to recover in the least stressful of environments. The temperature and humidity should be kept in the ideal range of 75-85F.

“Typically premolt animals enter their burrows with their abdomens markedly swollen by food reserves… After molting the animal eats its exuviae,which contribute organic materials and calcium salts needed for the new skeleton… Very little information is available in regard to molting of Coenobita. Coenobita clypeatus is reported to hide during the process most of which occurs in the shell (de Wilde, 1973). There is a noticeable reduction in activity for several days prior to the molt and after ecdysis the exuviae are positioned just in front of the mouth of the shell (A.W. Harvey, pers. comm.). During calcification the new soft skeleton of the chelae and other walking legs is moulded to fit the shape of the shell. If the animal increases markedly in size it may no longer fit neatly within the old shell and a rapid trade up in shell size may be necessary to avoid water loss and predators. There is no information available on calcium balance or storage through the molt or on growth increments of Coenobita. Coenobita clypeatus grows up to 500 g if large-enough shells are available” (Greenaway, P. 2003 p. 21)

Land Hermit Crabs that are eating foods high in calcium, fiber, chitin and foods high in nutrients their bodies need will often have a much higher molting rate; which slows with age or lack of larger seashells. If a crab is in a seashell, which is snug with no alternatives, they will not molt as readily as one with a vast selection.

Exercise is known to increase hunger, and thus will affect the rate of molting. In the wild, land hermit crabs have been known to walk many miles a night, and graze on foods along the way. It would depend on location as to the amount of exercise and grazing a hermit crab will do, but we have to be aware that a hermit crab stuck in a tank will not be as strong and healthy as one which is allowed out of the tank.

A hermit crab can be safely exercised in the tank with a plastic hamster wheel.

Scientist Mike Oesterling of the Virginia Institute of Marine Science has noted this in Blue Crabs.

“In the summer months, food availability has a major affect on shedding activity. If a crab does not satisfy the physiological need to shed (increased muscle tissue, body cavity ‘cramping’, etc.), it will not enter the molting cycle. In other words, if it doesn’t get adequate nutrition it’s not going to grow.” (Oesterling, M. 2003)

Hermit Crabs are social animals, and as such, there is usually a ‘pecking order’ among groups or colonies. As with many animals and organisms, when there is a scarcity of resources you will see a ‘pecking order’ among hermit crabs. The resources most important to hermit crabs being protein and calcium-rich foods and varied diet; hiding spots; space to dig down to molt; different sizes of seashells; water; and salt water.

If a crab is ‘top crab’ than it would get the most food, like with puppies and seagulls. We see this on a small scale within the crabarium, where hermit crabs vie for position in the food bowl or a favourite hiding spot. I have often watched my jumbo hermit crabs fighting for access to the salt-water bowl or Treat dish. It is not unusual for them to fill the bowl completely and keep other hermit crabs away, defending their right to eat first.

Hermit Crabs grow through molting. If you notice a hermit crab pre and post molt you will see very little difference, but over ten or twenty years it is quite significant. Another way to tell age is to look at the thickness of antennae and the little ‘teeth’ on the cheliped/grasping claw.

To be able to do this, your hermit crab will need a lot of moisture. You might find your crab near the water dish a lot prior to a molt. If you were to watch your crab molt, you would see your crab stretch and twist until the exo splits, then slips out of it like a suit. Some crabs cannot do this in one piece, so you may see legs and claws strewn about.

Hermit crabs need to shed their exoskeleton every now and then, this allows them to grow and regenerate any missing limbs. You might have experienced the wonder and surprise at seeing a snake shed his skin. The shed skin looks like a duplicate of the snake, but it is only the cast off skin that didn’t grow with the snake. When a hermit crab grows its exoskeleton (skin) doesn’t. Imagine a pair of tight-fitting shoes. When your feet grow, your shoes do not. You need to go and get some new shoes which will fit.

“Land Crabs store large quantities of lipids in the hepatopancreas, perhaps representing an adaptation to the variability of terrestrial environments. Unfortunately, few comparative data are available. Charles Darwin (cited in Reyne, 1939) remarked on the fact that over a liter of oil could be rendered from a large B. latro. The hepatopancreas of this animal contains up to 83% lipid (Lawrence, 1970; Storch, Janssen, and Cases, 1982), becoming particularly fat prior to molt (Wiens, 1962). Land crabs may rely heavily on “lipid economy”. Lipid biosynthesis increasesmarkedly prior to ecdysis (O’Conor and Gilbert, 1968) concurrent with the degradation of muscle (particularly the chelae) that permits extracting the limbs through narrow joints in the old exoskeleton (Skinner, 1966b). Subsequent regeneration of muscle, and growth of new muscle tissue, will require nitrogen sources if based on stored lipids” (Wolcott, T. G. 1988. p 90)

Autotomy and Regeneration

“Crabs possess the ability to autotomise their appendages when trying to escape the grip of a predator. The appendages, which detach at preformed breakage planes, are able to regenerate, and require several molts to reach normal size (Weis 1978; Barnes 1986). Because the new cuticle is lost with the autotomised appendage, regeneration only occurs after a complete molting cycle has passed. At this point, the new limb continues to grow beneath the existing but it is doubled over in a folded position (Lee and Weis 1980). At the next molt, the newly generated limb may only appear as a bud or a stump, as it has not had the physical space within which to attain normal size. The new limb continues to grow in a folded position under the hardening exoskeleton until the next molt (Hobbs 1991). This process is repeated until the new limb attains its normal size.” (Charmaine Andrea Huet, 2000)

Hermit crab gel limb regeneration photos by Vanessa Pike-Russell

More articles on molting:
Is my hermit crab dead or molting?
Regulation of Crustacean Molting: A Multi-Hormonal System
On molting by Jad Johnson
All about molting by Lisa Loeske
CrabLoverDon on molting
Photo Credit: Carol of Crabworks. Photograph of the exoskeleton of a C. clypeatus land hermit crab taken in 1999 and used with permission. Maryanne Ponte, Vanessa Pike-Russell
University of Massachusetts Amhurst: Biology 497H – Tropical Field Biology.
St. John, USVI March 16, 2001 to March 25, 2001 Photo Gallery
URL: http://www.bio.umass.edu/biology/troptrip3/

Information references:

Charmaine Andrea Huet. Spatial Distribution Of Brachyuran Crabs In Sarawak With Emphasis On Fiddler Crabs (Genus UCA) As Biomonitors Of Heavy Metal Pollution. Institute of Biodiversity and Environmental Conservation UNIVERSITY MALAYSIA SARAWAK 2000

Dunham, D. W., and S. L. Gilchrist. 1988. Behavior. Pp. 97-138 in Biology of the Land Crabs, W. W. Burggren and B. R. McMahon, eds. Cambridge: Cambridge University Press.

Fletcher,W.J. and Amos, M. 1994 Stock Assessment of Coconut Crabs. ACIAR Monograph No.29 32p
Mike Oesterling of the Virginia Institute of Marine Science. Quote relates to blue crabs.
URL: http://www.blue-crab.org/fullmoon.htm

Fletcher, W.J., Brown, I.W., Fielder, D.R., and Obed, A. 1991b. molting and growth characteristics. Pp. 35-60 in: Brown,I.W., and Fielder, D.R. (eds), The coconut crab: aspects of Birgus latro biology and ecology in Vanuatu. Canberra, Aciar Monographs 8.

Fox, S. (2000) Hermit Crabs : A Complete Owner’s Guide. pp. 27. Barrons Books : NY

Greenaway, P. 2003. Terrestrial adaptations in the Anomura (Crustacea: Decapoda).
In: Lemaitre, R., and Tudge, C.C. (eds), Biology of the Anomura. Proceedings of a symposium at the Fifth International Crustacean Congress, Melbourne, Australia, 9-13 July 2001. Memoirs of Museum Victoria 60(1): 13-26.

Greenaway, P. 1985. Calcium balance and molting in the Crustacea.
Biological Reviews 60: 425-454. Herreid, C.F. 1969b. Integument permeability of crabs and adaptation

Grubb, P. 1971. Ecology of terrestrial decapod crustaceans on Aldabra.
Philosophical Transactions of the Royal Society of London B 260:

Held, E.E. 1965. molting behaviour of Birgus latro. Nature (London)
200: 799-800.

Hobbs, H. H., III. 1991. Decapoda. In Ecology and Classification of North American Freshwater Invertebrates. J. H. Thorp, and A. P. Covich (eds.). Academic Press, New York, NY, p. 823-858.

Osterling, M. molting and the Full Moon. Online article [URL http://www.blue-crab.org/fullmoon.htm”>

Wolcott, T. G. 1988. Ecology. Pp. 55-96 in: Biology of Land Crabs (W. Burggren and B. McMahon, Eds.), Cambridge University Press, New York.