FAQ

The Crab Street Journal FAQs

FAQ How can I keep my tank warm during a power outage?

Check the substrate temperature too!

FAQ How can I keep my hermit crab tank warm during a power outage?

When the power goes out the biggest concern is keeping the crabitat warm. Allowing the temperature to fall below 72F is dangerous. We don’t have any data indicating at what temperature a crab will die or how long it can be exposed to this temperature before dying. Hermit crabs are tropical animals so they are not meant to endure cold temperatures for extended periods of time.

This article will suggest some ways to insulate a crabitat or deal with a power outage/lack of heat. Some of these ideas will also work in a pinch if your tank heater fails and you can’t get a replacement right away.

If you know the storm is coming start insulating the tank BEFORE the power goes out. You should also turn up the heat in the house. If the house is 80F when the power goes out it will stay warm longer than if it was only 70F.

If you can’t safely move the tank, consider moving everyone else to the room with the tank. Block all drafts coming in, cover the windows with blankets, keep the door to the room closed to hold in the warmth. Moving a tank with molters down is a bad idea and should only be done in a situation where the crabs will die otherwise. Moving a tank will cause molt burrows to collapse.

Insulating the tank:

  • Cut thick pieces of styrofoam/Foam/foamboard to make a crab-gloo. You could also buy extra Reflectix to have on hand for this purpose. Cover all sides. Tape in place so it holds together. Once the power is out cover the top also. If you don’t have an overhead light, cover the top immediately.
  • Next drape and emergency blanket over the tank. Make it snug all the way around.
  • Next layer a heavy blanket over the emergency blanket.
  • Avoid opening the tank to check on them once you have it insulated, this will just allow the warm air to escape faster.
  • If your oven is gas you can use it to heat water or stones to add to the tank to maintain warmth.

    Hot water bottles can be made from any empty plastic bottle. Boil or heat the water and then add to the bottle, place the bottle in the tank. If the bottle is a small opening (like a 2 liter) you can leave the cap off. If the bottle opening is large and a crab could potentially fall in, leave the cap on. You can also use your oven to heat up a brick, some slate tiles or stones. Soapstone holds heat longer than any other rock.

    Disposable hand and foot warmer packs are better than no heat at all and if wrapped in a towel they might hold their heat longer. Some are good for 72 hours.

    In a dire situation where you can can’t evacuate you could use terra cotta pots and a candle to make a room heater. Do this at your own risk!! I do not know how well this works or the potential dangers. Again it’s not just for fun but if you are desperately cold and can’t leave your house it might be enough. Please do not leave this unattended and burn down your house!!!!

    You should consider building a plastic bin temporary crabitat in case you need to evacuate with your crabs. You can see what that looks like in this video by Mellissa Archambault.

    If you are forced to evacuate and you have molters down you have a difficult decision to make. If you think you will only be gone 24 hours, it may be safe to leave them behind. This would be based on how cold the house has become. Sand will retain heat longer than air so molters have a bit of insulation and that may be enough to carry them through a 24 hour period. If there is a chance you will be gone longer and/or the temperatures in your house are below 50 degrees, you may want to risk digging up the molters to take them with you. This is a decision you will have to make based on your current set up and situation. Digging up a molter *can* kill them but freezing temps will definitely kill them.

    What should be in my emergency hermit crab kit?

  • Pre cut pieces of your chosen insulation for all four sides and the top, or a roll of Reflectix
  • An emergency blanket or two, enough to cover your entire tank
  • A heavy blanket big enough to encase your entire tank
  • Tape to hold the insulation in place
  • An empty jug or two for hot water
  • Some soapstone, bricks or slate for heating
  • Disposable heat packs


  • What follows is the original discussion from our Yahoo group many years ago. I have no knowledge of kerosene heaters so I can’t speak to their use or safety.

    Because of last night’s storm, power went out and we were out almost a full 24 hours. The temperature in the crabitat dipped to 55 degrees and all the little crabs half dug themselves into the sand and hid in their shells. I have four PPs and a strawberry. It looks like they all came out okay. When the temperature came back they were active again. I tried not to worry too much because I was in Florida during a cold spell and it got as low as the 40s and even high 30s at night. I was more concerned about my strawberry iPinch because I don’t think cold spells are too common where she comes from.
    It looks like some other folks aren’t so lucky. They will be out of power for days. I used a blanket to cover the habitat and try to keep it warm for as long as possible, and I think I should make a fully-encompassing ‘Crabgloo’ for such emergency occasions to try to keep heat in for even longer.

    Has anyone else had this sort of problem? How did you solve it? What do you suppose a cold-region crabber should do when something like this occurs?

    Ladybug15057 answered:

    Friday before last we had high winds of 60 mph and it broke the top off of my neighbor up the streets pine tree off. The top landed on the power lines, wrapped it self up in them and tore down the lines. We were without power for over 24 hours, and I noted even with me burning in our wood burning stove, (but the blower didn’t work due to no electric) the room was at 72 but the tanks began to dip below 70 and so did the substrate temp. What I did was I made up some soda bottles with hot water in them. I placed these in a couple places on the warm end of the tank to try to help keep the surface sand warmer. (which it did) I also used blankets to help keep some of the heat in.

    Aaaamory
    That’s a good idea. Our water heater is gas. How useful that turns out to be! We also have a fireplace but don’t use it because of our parrot. The vet specifically advises against it. Good thing outages don’t happen too often. Maybe once a year or every other year (one year it was a squirrel exploding inside a transformer).

    Ladybug15057
    Prior to me having so many tanks in our home, a hot water bottle also works to help keep an area of the substrate warm, but with so many tanks now…I would have a small fortune in hot water bottles.

    starmaiden
    I live in the Pacific NW too! Some storm that was eh! Wow! I was one of the lucky ones in this area and only lost power for a few hours. Some people are still without power.
    One year, after an ice storm, I was without power for a week! Fortunately this was before I had hermies! Unfortunately, everything in my house is electric except the wood burning stove, so I was cooking with my camp stove out in the snow.
    I always wondered what I would do for my crabs and bettafish should that happen again. I’ve even thought about buying a generator because it seems the power goes out frequently in this area due to storms. I like ladybug’s suggestion of pop bottles filled with warm water.

    Ladybug15057
    An added plus, because I too live in an all electric house and the hot water tank will only stay hot for so long too…but with a wood burning stove, one can heat cold water for the soda bottles too. (been there and done that as well) One can also warm water up on a kerosene heater if one has this as a back up heating source if the power goes out.

    Nora
    That storm was a stinker!The power was out for awhile! What I did for the hermies was to heat up rocks on the woodstove,placed them in orchid pots(clay pots that have holes on them) and put them in the tank. I also heated slate tiles,placed them on cookie sheets and put them on top of the tank, then iglooed the tank in with foam insulation and a space blanket. The tank stayed at 69 temp. and 75 humidity.
    The wind was phenominal. The woodstove really couldn’t belch out enough heat to keep the hermies toasty in the other room,considering the fan was useless.
    Are there links to emergency heating methods. It might be a helpful to others to see different coping methods when the power goes out for an extended period of time.I would like to download a list of heat approaches for the next time. I hadn’t even thought of ladybug’s hot water bottle method of heat. I know I worried about the hermies more than the tree that landed on my house!

    Ladybug15057
    Nora, thank you for the rock idea too…that’s one I didn’t think of. Being in the country I do have plenty of them, now to think of what to put them in to help out with the warming of the tank. Thank goodness power outages do not happen very often around here, and especially for extended periods of time.

    And please all, if anybody is going to use a kerosene heater for warmth make sure it is safe…they do require maintenance. Here are some links for reading for maintenance of kerosene heaters too: (I posted this on Hermies Group too because the question of keeping hermies warm came up today)

    I did a little searching, and it appears that with the cotton wicks one should not burn the wick dry. (I never had or knew there were cotton wicks) But when we did burn ours dry, thre was always a blackish residue on the top of the wick and it was a little hard. So I did get a toothbrush and went along the top of it. This did scrape majority of the black off and made the top of the wick soft again. But here are some links that maybe of some help so you hopefully will be prepared: (and the kerosene heater should always be stored dry)

    Main link with reading:
    http://www.milesstair.com/wick_replacement.html

    CARE AND MAINTENANCE OF KEROSENE HEATER WICKS

    http://www.milesstair.com/Kero_Heater_wicks.html

    REGULAR MAINTENANCE FOR KEROSENE APPLIANCES

    http://www.milesstair.com/regular_maintenance.html

    Due to this storm moving east, I live in southwestern Pa, so got all my hermie heater gear together today just in case.

    FAQ Can other animals live with hermit crabs?

    Skyguyx5 asked:

    Ok, I have seen a few posts about putting worms and other pets into the crabitat that I wanted to see what else we could put in there. Ive been thinking of putting another kind of animal in with my crabs because it will be more natural for them to be around other animals, like in the wild. So here are some that I came up with and some that Ive read about online. Thoughts and additions MORE than welcome!

    Frogs (I think rottigirl has them in her tank????)
    Millipedes- they seem to have almost the same needs as crabs?
    Worms – ????
    Fiddler crabs– you’d have to redo your tank for the fiddler crabs to have a lagoon type thing??? but will they take over the tank a bit?
    While I think it would be fun to have other animals in there with the hermit crabs, I don’t want the other animal to be a hunter of hermit crabs, or the hunted… lol What else lives peacefully among hermit crabs in the wild?

    LolaGranola answered:

    Generally a bad idea because it’s a closed system. Hermit crabs go dormant during a molt and are very vulnerable to any kind of carnivore. A crab that would normally ‘move away’ to a new area to avoid other animals would be stuck in the tank which would provide an additional stress.

    FAQ How can I cool down my tank?

    Morganthe asked:

    My sisters and I received crabs over the summer. They were seperated for a while because of budget constraints (we had three small plastic fish tanks, but nothing big enough for multiple crabs) but have since been moved into one large tank back in my bedroom, a glass ten gallon with a glass fishtank lid. Their living conditions are better now than they were, but theres still one concern. My parents HATE the things, and when my apartment goes through I’ll be taking them with me, but for now they are trapped in the south-east corner room of the house. I live in the desert and this room is always warm. Ever yheater I could kept tempertures steady at a level above the ambient room temperature, but my room temp is already too high (85F). I’m currently hanging dechlorinated ice cubes from a thin bag with a fan near the tank. I spary the glass top of the cage to keep the humidity up. This works fine in the afternoons and on weekends when I can attend to the crabs hourly, but I need to find a way to regulate the temperature when I’m not around. I’m currently turning off the fan while I’m away, which increases the temperature, but prevents high evaporation rates. Does anyone know of anything that will lower the temperature in the tank? I’ve read everything I can get my hands on, but they all seem directed at people who have cold winters and pleasent summers.

    Ladybug15057 answered:

    Prior to getting our central air conditioning, our tanks would hit in the upper 80’s. Using a fan does help to circulate the air, but unfortunately dries the humidity in the tank which the hermies need to breath. What I had done, was I saved 16 oz. plastic Pepsi bottles. I filled them 2/3’s full of water and put them in the freezer. I used a Kool Aid cap (or other plastic lid) as a drip basin and pushed this in the substrate. I then put the frozen soda
    bottle in the Kool Aid lid, with a couple of small sponges around the space between the Kool Aid lid and soda bottle so the little hermies didn’t get stuck and freeze to death. This made a cool place in the substrate if the hermies wanted/needed a place to cool off at. We did have a couple of hermies throughout the day that took advantage of the cool substrate in all our tanks. One thing I noticed about the frozen soda bottle, was that the outside of the bottle would be full of condensation, and at times I would have to empty the Kool Aid lid. I also noticed the humidity of the tank dropped, which meant that I had to use larger sponges to keep the humidity up.

    PS. If you choose this method, start saving your soda bottles. The soda bottles would keep ice in it 4-6 hours on a ‘hot’ day. I would exchange these about 3-4 times a day, refreezing the ones I took out of the tank. Make sure to keep a close eye on the humidity level. The soda bottle will pull some of the humidity out of the tanks air so you may need to supply other water sources as well to keep the humidity level up. (you do have a lid for your tank right to help hold humidity within the tank?)

    FAQ What is the difference between a thermostat and a rheostat?

    Written by Stacy Griffith

    A thermostat tests the temperature then turns the heat pad or light on and off to keep the temperature in a certain range, like the one in your home that controls your heat or air conditioning. Some thermostats come with a probe you can insert into your substrate.

    A rheostat or dimmer is a dial that allows the user to adjust the level of heat/light based on their preference but is not automated in anyway. It works like the volume knob in your car. Rheostats can be used with a thermostat but it’s not necessary.

    FAQ How do I create and maintain humidity in my crabitat?

    FAQ How do I maintain humidity in my crabitat? Photo credit Amber Miner

    The first step to creating and maintaining humidity in your tank, is a good lid. A screen lid alone is not sufficient. A glass/plexiglass/lexan lid, cut to fit is the best option.

    Plexiglass/lexan can be purchased at most hardware stores and be cut to size for free. This can be placed on top of your existing screen lid for stability.

    Coroplast is another good option for a lid. This can be placed on top of your existing screen lid for stability.

    In the short term, you can use plastic wrap over the screen lid. Some people use cardboard and wrap it in plastic or tape.

     

     

     

    Water Dishes:

    Your tank should have two types of water bowls, salt and fresh. Use bowls that are wider than they are deep but still accommodate your largest crab and allow it to submerge. This increased surface area will create more humidity. Water dishes may be placed next to your heat pad or beneath your overhead light to produce additional humidity. Adding bubblers/air stones to the water pools will boost humidity.

    Natural moss:

    Crabs love moss! Placing moss anywhere in your tank and keeping it damp will raise your humidity, especially next to the heat pad. Rewet/replace as needed. You can buy moss in bags or compressed bricks. Sphagnum moss is a favorite and it holds up really well in the crabitat long term. If you can’t find sphagnum, look for Hiawatha or sheet moss, terrarium or frog moss, natural and un-dyed. Moss does not need to be cleaned or replaced for cleanliness.

    What Moss is Safe?
    Is Beaked moss safe?
    Is Sphagnum moss safe
    Is Cypress safe?
    Don’t Forget the Moss

    Wood: Choya, cork bark and other safe woods can suck up the humidity in the air but once saturated can help maintain it.

    Things to avoid

    Soaking your substrate is not the way to raise humidity.

    SLIGHTLY moistening the substrate next to the heat pad is ok. Water logged substrate is not safe for molting hermit crabs and will encourage the growth of lethal bacteria.

    Foggers: Foggers and misters can easily flood your tank and lead to lethal conditions for molting crab or trigger a bacteria bloom. Use with caution.

    Sponges: Sponges were once considered a staple in the hermit crab tank but there are better solutions to the humidity issue. Sponges placed in the fresh water will raise humidity. Sponges should be changed out daily, sterilized and replaced with already sterilized sponges. Sponges placed in the salt water will become nasty fast. Due to the upkeep of sponges it’s easier to go with moss.

    Emergency fix:

    If you have just discovered that your crabs need humidity and you are not able to fix the problem immediately you can place a wet towel over the tank and some plastic wrap on top of the towel. The towel must be kept wet and it must have plastic wrap over it or as the towel dries out it will absorb the moisture from the tank. This is not a long term solution.

    You can also mist the tank with dechlorinated water near the heat source. This is not a long term solution either as the humidity will fluctuate too much between misting to be suitable. You also risk flooding your tank by over misting.

    Originally posted at All Things Crabby The Hermit Crab Care Blog

    FAQ Is Polyvinyl Chloride/PVC Pipe safe to use in the crabitat?

    FAQ Is PVC pipe safe for hermit crabs?

    FAQ Is PVC pipe safe for hermit crabs?

    CrabbyAbbey answered:

    PVC isn’t a safe product to be used in a closed environment or with land hermits that tend to taste sample their surroundings, or really anywhere for that matter.

    It’s production includes chlorine and lead and it leaches chemical gases into the air, especially in heated areas. In closed areas like crabitats these dangers are even more harmful.

    My largest tank is a reef tank and removing the installed PVC plumbing opens two holes at the bottom of my tank. When I bought it 2 years ago I thought a wise way to address that was to wrap the PVC with sisal rope. It solved the problem and gave the crabs something tall and fun to climb and hang out on. Once I realized the dangers of it I removed the pipe and had the holes sealed with a small square of plexiglass.

    Stacy answered:

    Something I found on a bird forum:

    So going off memory, basically the High Definition PVC (furniture grade) is the best. It’s been deemed safe and used to make items for children. It doesn’t contain dioxins, plasticizers or harmful metals.

    What is Furniture Grade PVC?

    CPVC (the cream colored PVC) is safe to use for hot and cold water, whereas PVC is only safe used for cold water. The CPVC doesn’t degrade in the sun like PVC does and CPVC also doesn’t off-gas if heated up. Heated PVC will off-gas a colorless, odorless fume which is toxic. CPVC is smaller than the PVC. CPVC goes by the outer diameter measurement whereas PVC uses the inner hollow hole size as it’s measurement.

    I wouldn’t use the Schedule 40 white PVC to build anything that could possibly get too warm or be outside in the sun.

    I also wouldn’t make something out of PVC that would be chewed on; like a hanging toy or foot toy. I made a shower stand out of PVC years ago, it serves it’s purpose and the birds don’t chew it.

    Toxic chemicals need to be removed from schools and daycares

    Polyvinyl Chloride – PVC

    THE DANGERS OF POLYVINYL CHLORIDE (PVC) from US Safety

    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.

    Encyclopedia.com

    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
    and
    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
    http://www.webcastmy.com.my/unimasresearchgateway/thesis/thesis_0062/chap1.htm

    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:
    411-416.

    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.

    FAQ Should I feed my hermit crab meat?

    This is a compilation of forum posts from our old site.

    Hermit crabs devouring a piece of unseasoned steak-photo courtesy of Stacy Griffith

    FAQ Should I feed my hermit crabs meat?Hermit crabs devouring a piece of unseasoned steak-Photo credit Stacy Griffith

    Rachelrmf posted:

    I really was not all that big on the meat thing untill i came here and read that so many of you feed alot of meets. So i have alway put a little crab or shrimp or tuna in for them, but just every once in a while. So I was wondering is it on a daily basis that you should feed the meat. I have been changeing out fresh every day but can’t really tell about how much of it they are eating because they like to party at night so the food is everywhere. And also how often do you change out the differant meets. I don’t want to upset their little tummys and i know they are not close to dogs, but with dogs it can upset them a little. Well as far as that goes i guess how often do you change out all your foods. For me every week they get 3 sets of choices greens, leaves, seaweed and then on fruit mango, fresh coconut,bannana and on meat oyster,tuna,sardine treats are nuts and rosehipp. Should i be adding in better things for them? I do have to say they eat better than i do as far as fresh wholesome foods! Lol

    SUE wrote:

    rachelrmf, this is a good question, and one that is continually evolving based on what is observed and coming to be known in terms of what constitutes a robust diet for crabs. I am going to provide a breakdown of the specific food groups and what they are generally good for. Note that I will not have included ALL the foods in the category, and some categories overlap in one or 2 areas too. I try to offer daily a food from each group. I used to also leave home made dry kibble, worrying that they do not all eat at the same time or each thing (which they don’t) but I have a lot of crabs, and I have learned for my herds, the general proportions to offer. I have stopped leaving dry goods in at all times, and find that their foraging is better, and I waste less food! I still feed them dry goods daily, just minimally, and I usually sprinkle it on something that it will stick to like juicy fruit or vegetables. This is something I do because I have tested and offered these foods to the crabs in trial alone before!

    Scientists evaluate that crabs use a natural selection imprint to prevent themselves from eating only one type of food source and thus harm themselves with not getting all food resources needed. They are also imprinted to ignore foods that have been smelled or eaten within a 9 -14 hour period of time, and one of the reasons relying on commercial foods is so dismally inadequate. They are not of the type of animal that relies only on one type ofr food like protein, or vegetation or calcium, etc. They must have a robust combination of all of them! Many of the foods must support their ability to metabolize to their environment (heat, humidity, light, growth) and they require a balance of ALL these types of food resources (some more at specific times like pre-molt, or PPS) in order to thrive.

    These groups are classed in the following way and I will include why:

    Protein and lipids: this is for energy to grow, forage, reduce competition or minimize cannibalism which more frequently occurs in captivity.

    Foods in this class are:

    meats, fish like silver sides, gold fish, clams, oyster; bone marrow (all meats including poultry), nut meats (many also fall in the omega fats group) salmon skin(including fat). Some vegetation like avocado meat (only) and bamboo stalks. (which also provide Cellulose, high energy)

    Carotenoids, zeaxanthin and cellulose: these foods are necessary to assist the crabs metabolic functions of calcium absorption, processing of minerals, and coloring an individual crab has (darkens pigments). It also improves the crab’s immune system and nervous system functionality.

    Foods in this class are:

    tannin rich leaves, bark, cambium (inner branch skins) of plants like oak, maple, mangrove root, some perennial leaves; fresh fruits and vegetables that are orange, yellow, red or dark green (i.e. squash, sweet potatoes, carrots, natural corn, mango, blue berries, etc); many flower petals (dry), spinach, foliage, bean sprouts, seaweed: spirulina in particular, reptile moss (from pet store) etc.

    Carbohydrates: these foods are quick energy foods that will help your crab by immediately fueling them but saving their “stored” reserves necessary for metabolic function.

    Foods in this group include:

    grapes, apple, honey, wheat germ, oatmeal, dried fruit (raisins mostly due to Copper sulfate use in others), banana, pineapple, citrus pulp (inner membrane of skin considered cellulose).

    Omega fats: this food group is very important and is totally missed in commercial food formulations unless they are frozen foods! These are necessary for nervous system, exo-skeletal health and processing of carotenoids and other minerals. If there are deficiencies in this group it is typically exhibited by molt death (where you are uncertain), a mildewy appearance to the exoskeleton (they look dehydrated), and they are not active! Foods in this group overlap proteinous groups.

    They include:

    Coconut, walnut, whole fish (like a dead gold fish), fish skin, animal fat, olive oil, some grass seeds, seeds, peanut butter, etc. There is a mirade of these suitable, some found in fresh flower petals like roses, sunflower, crab apple blossom, etc. Take a look at the edible plants list at Epicurean Hermit!

    Calcium: it is considered superior to provide more than one natural form of calcium! Calcium of course is used mainly for growth of the exoskeleton. Calcium without the support of light and carotenoids will not be properly absorbed by the crab! The acceptable form for supplementation outside of natural forms is Calcium carbonate powder ONLY! Foods containing calcium, will also provide some proteins as well.

    Here are the main foods ideally used:

    freeze dried brine shrimp, meal worms, blood worms, krill (fresh, frozen or freeze dried), shrimp tails, sand dollars, powdered oyster shell, cuttle bone, broccoli heads, milk.

    extra resources relating to the above: http://www.epicurean-hermit.com and http://hermitcrabcuisine.com (this site lists specific food groups for each food)

    Steam all shell fish prior to offering to hermit crabs!

    FAQ Are gold/feeder fish safe to feed hermit crabs?

    FAQ Are goldfish safe to feed to hermit crabs?

    FAQ Are goldfish safe to feed to hermit crabs?

    This is a compilation of forum posts from our old site.

    To date we have not confirmed whether diseases fish may have can be passed onto hermit crabs.


    Sat Mar 05, 2005
    Ladycrab wrote:
    Bought some gold fish for the hermies. Froze them last night just need to know if they need to be prepared any special way before serving them???

    Julia_Crab wrote:
    There’s a bit of controversy afoot about the goldfish method right now. Freezing is a great way to kill any bacteria that might have affected the crabs, if any, though. I’m still not convinced that crabs can be affected by bacteria in the food, but I’m waiting to hear back from a scientist about it.

    Thaw your fish and soak them well in some ocean water, then just serve. This is one food you may want to remove promptly in the morning, as it can get smelly. Don’t be disappointed if they don’t eat it the first time, either. Sometimes it takes them a couple of tries to catch on.

    kvh4 wrote:
    I would rinse them in declor water and then soak them like Kali_ma said. I know that store employees are SUPPOSED to treat the water these fish are in, but I know for certain that some stores don’t care, and so a lazy or incompetant employee can mean feeding clorine to your crabs.

    They hire just about anyone these days….

    ladybug15057 wrote:
    Freezing does not kill all bacteria’s, but boiling for 5 minutes does.
    (but won’t remove any chemials used that may be on/in the fish)

    Julia_Crab wrote:
    The theory that I share with a few others is that aggression problems are mainly caused by nutrient deficiencies, though we are uncertain which one or ones.

    I heard about this about a month ago from some other crabbers on another forum. I told a few people about it, and tried it myself.

    It’s not for the faint of heart, though. The preferred method is to murder the feeder goldfish by putting them in a bowl of the crabs’ ocean water. The theory is that the action of the fish drawing the salt through their systems makes it more attractive for the crabs to eat. When the fish are floating belly up, serve them to the crabs, being sure to remove them within 24 hours or so.

    I still feel slightly guilty doing this, as the fish basically suffocate. So I’ll tell you the alternative method, which is to put the bag of feeder goldfish in the freezer until they “go to sleep.” Then soak in salt water and feed to the crabs. It takes longer for them in the freezer, several hours, I’m told. It usually takes less than 20 minutes to kill them in the salt water.

    I’ve been told this isn’t humane. I can’t really argue with that point of view on the one hand. However, these fish are all doomed, either to be suffocated or put to sleep for our crabs, or fed alive to arowanna and oscars. So it’s really a choice you have to make for yourself. Like Angel, several people report no more aggression in the tank between crabs, doing this feed once every 7-10 days.

    As a note, my crabs always eat the eyes, then the brains, then , if they’re still hungry, they go for the intestines. The same effect might be achieved from feeding fish heads and guts from the fishmonger. But it would definitely be much more smelly and messy. With goldfish, you can choose the size you want.
    Don’t put it in the crabs’ water bowl, just some water you’d make for them, LOL. Sorry I wasn’t clear.

    Just put the whole fish in the food dish. Sometimes I sprinkle them with spirulina first.

    kvh4 wrote:
    I know that everyone has their hermit crabs’ best interest at heart, but I have to say that this sort of practice seems very hypocritically cruel.

    If someone had a hermit crab in a habitat that was too dry, and it’s gills were being damaged so that it died by suffocation, we would all be very upset, but somehow doing it to a goldfish is okay?

    I get the feeling that it would be very easy to get fish guts from your local fishmarket, so this whole suffocating a goldfish thing is very un-necessary.

    Vanessa wrote:
    I have decided not to feed my crabs goldfish, but I do agree that feeding them fresh fish is recommended. I prefer to give them from the fishmongers (seafood store) than from a pet store.

    I prefer to offer the food in a buffet tub since I’ve h ad problems with crabs dragging their food around the tank and burying it for later
    I prefer to offer a small fish or the head of a fish rather than a goldfish. I have kept goldfish as a pet, and I feel bad about killing them myself. I have also heard some negative things about giving feeder fish to hermit crabs. If I was to give my crabs a small fish to eat, I would breed them myself or at least quarantine them for a while. More on that further on.

    Fresh seafood I have offered my crabs:

    o Fish / Fish head (raw or steamed)
    o Small fish (bait fish, caught in clean waters)
    o Sardines (raw or canned in spring water)
    o Prawn heads and full prawns (raw or steamed)
    o Scallops (raw or steamed)
    o Cuttlefish (raw or steamed)
    o Crab Meat and Shell (cooked)
    o Cockles
    o Conch
    o Mussells (raw or steamed)
    o Squid (raw or steamed)
    o Marinara Mix – all of the above (raw or steamed)

    I was talking with MrsPoppyPuff on this subject, and she suggested fresh fish as used in Sashimi (sushi style based on raw fish, cut in thin slices). I also offer my crabs the very fresh raw fish for sale in The Bento Box in Wollongong (near Sydney)

    Not only is this fish very fresh, but it comes in finger size pieces or thin slices. Perfect for offering to hermit crabs
    I might have to check with my local seafood store and look out for a goldfish-sized fish to offer as an alternative. Garfish and Whitebait are two types of fish sold for human consumption which are small enough, but I have a feeling that the large gelly eyes of goldfish would be more appetising than that of garfish or white bait.

    I know that the crabs are welcome to the head and eyes of any fish that is cooked for me. I cannot stomach eating a fish while the eyes are staring up at me

    ***Note: This thread started in March 2005 and continued through May 2005. There has to date (7-29-09) still been no replies as to whether any diseases can be transmitted to hermit crabs. But about a couple of years after this thread was done an outbreak of bacteria happened among some hermit crabs due to oysters.