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by Stacy

The CrabStreet Journal was featured in a movie

March 16, 2014 in General

In 2011 The CrabStreet Journal was contacted about featuring our print magazine in a film tenatively titled Imogene. We granted permission of course! In 2013 the film was released a major motion picture under the title Girl Most Likely featuring Kristin Wiig, Matt Dillon and Annette Benning. Below is a screenshot of our cameo. How exciting!!!

The CrabStreet Journal cameo in the movie Girl Most Likely

The CrabStreet Journal cameo in the movie Girl Most Likely

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by Stacy

Tips for Photographing Your Hermit Crabs

March 3, 2014 in General

Written by Robin Wood

Click to open the PDF

Tips For Photographing Hermit Crabs-Robin Wood
Tips For Photographing Hermit Crabs-Robin Wood
Tips for Photographing Hermit Crabs-Robin Wood.pdf
103.7 KiB
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by Stacy

What size is my hermit crab?

March 3, 2014 in General

Open the PDF Size Chart below and print it out. Compare your hermit crab to the chart to see what size it would be generally accepted as. This is a chart created by the hermit crab community to have a general guideline for size categories in reference to our hermit crabs.

61.7 KiB
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by Stacy

Distribution of Coenobita – Hermit Crabs

March 3, 2014 in Biology, General

We’ve created a chart of the distribution of coenobita – hermit crabs. Click the gray box below to view the chart.

105.0 KiB
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by Stacy

Manufactured Sea Shells

February 18, 2014 in General

Interview with Amy Youngs regarding her plastic shell prototypes

Makerbot 3D Hermit Crab Shells

Glass Hermit Crab Shells

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by Stacy

The Newbies Guide to Hermit Crabs

February 18, 2014 in General

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.


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?

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

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by Stacy

Emergency Help Questions

February 18, 2014 in General

AFTER reading the info in the Emergency Help Links ‎ if you still require assistance, please answer the questions below. Copy and paste the questions into a new topic titled ‘Emergency Troubleshooting’ and then answer each question.

We will do our best to help you in a timely manner but understand that no one is monitoring this forum 24/7. You can help yourself first by reading the extensive information we have provided.

By answering ALL of the questions you will make it easier for us to help you. It may even helpyou identify the issue on your own. If we have to question you at length for details it simply delays the process of determining your issue.

If you are unwilling to answer all of the questions, understand that your post will not be given priority in determining the order in which to answer new help requests.

***** Begin Copying Here*****
Briefly describe your problem:

1. Substrate used in crabitat? In iso?

A. What is the depth of the substrate?

B. Is the substrate moist or dry?

2. Humidity percentage level in crabitat? In iso?

A. What style of humidity gauge do you use? (Dial or

B. Where is the gauge located in the crabitat? (top, middle,
Substrate level…left side, middle, or right side of

C. Are there any water sources near where the gauge is

D. Did you test the humidity gauge for accuracy? (by
calibrating It?)

3. Temperature of substrate in crabitat? In iso?

4. Air temperature of crabitat? (what the inside wall thermometer
reads) In iso?

A. Where is the thermometer located within the crabitat?

5. All items and decorations within the crabitat? In iso?

A. Were items boiled that could be boiled, baked that could
be baked, or washed with hot water prior to being placed
within the crabitat?

6. What type of water is offered to the hermies? (bottle or dechlor
tap water?)

A. If you use a dechlorinator what brand do you use?

B. How often to you exchange the water for fresh water?

C. What do you use as water dishes? ( and how deep are they?)

7. Do you offer an ocean water source?

A. What brand name of ‘ocean’ water do you use?

B. How do you prepare the ocean water offered? (amount of
dechlor water to ocean mix)

C. Is it shaken after being mixed, and before offering?

D. Is it left to sit and dissolve for at least 12-24 hours?

E. If you have an ocean pool with a filter, how often do you
change the filter?

F. When the ocean water level becomes low in the pool, do you add more fresh or ocean water to raise the water level?

8. What are all the foods offered in main crabitat? (commercial and fresh)

A. If you offer fresh fruits, veggies, and meats within the crabitat how long are they left in the crabitat before you replace them with fresh foods?

B. If you offer commercial dry foods, how often are they replaced?

C. Is the substrate checked daily for fresh foods that may have been dragged out of the food dish and removed?

9. What are all the foods offered to a recovering molter after they eat their exo?

10. What type of crabitat do you have? (glass, acrylic critter keeper, plastic, other)

A. What gallon size crabitat do you have? (if not known what are the measurements?)

B. How many hermies do you have in your crabitat?

C. Is there a second level to the crabitat?

D. What type of lid do you have on the crabitat?

11. Type/form of heat source used on main crabitat? On iso? (lights, an UTH sold for reptiles, or other source…if other please

A. If you use a light on the crabitat, what size watt is it?

B. Is it extend on ½ or all of the tank top?

C. Do you provide a night and day cycle?

D. If you use a Reptile UTH for what size tank is it rated for? (if not known what is its length and width measurements?

12. How long you have had the hermie/hermies?

A. Have they molted since living with you?

B. If so, were there any complications? (limb loss, didn’t eat their exo, etc.?)

13. Were they bought from the same pet store/place?

14. What species of hermies do you have?

A. What style and type of shell are they wearing? (Painted or natural)

B. What style and type of extra shells do you offer?

15. Do you bath your hermies?

A. If so how often and do you add anything to the water?

B. What is the water temperature if you bath your hermies?

C. Where do they exercise/drip dry off afterward?

D. Is the area they drip dry at warm?

16. If you take your hermies out to exercise or play, do you mist their gill area first?

17.. Has there been any cleaners, paints, perfumes, air fresheners,(including plug in’s), candles, smoking, any form of ‘smells/odors’ where their crabitat is? (remember, even though one may use an air
freshener in one room, including deodorants, etc…the scent does travel)

A. Are all hand lotions, or other smells/odors washed off of your hands prior to handling the hermies? (including
scented soap)

18. How often do you sterilize/deep clean the crabitat & how do you sterilize it?

A. What do you use to clean/wash the inside of the crabitat?

B. How often do you spot clean the crabitat for hermie wastes?

C. Has there ever been any pests noted within the crabitat? (ants, mites, gnats, etc.?)

D. Has there ever been any mold or mildew noted in the crabitat?

E. Where are the hermies when the tank is deep cleaned?

19. Are there any odors/smells ‘within’ the crabitat?

A. If so what would you relate the odor to?

B. Is there an odor on the hermies?

C. If there is, what would you relate the smell to?

20. Do you use sea sponges in the water supply?

A. Are the sponges rinsed daily with dechlorinated water?

B. Are the sponges exchanged at ‘least’ every 2 days for fresh sterile ones?

21. Have you added anything new to the crabitat recently…new substrate, decorations, changed water dechlorinators or ocean water mix?

If there is something you feel is also relevant that has not asked here, please do include it. This will all be needed for us to try help troubleshoot if there is a potential problem.

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by Stacy

Emergency Help Links

February 18, 2014 in General

Coenobita compressus

Get Help! I’m afraid of heights!!

We are sorry that you are experiencing a crab care emergency. Below are some links and information to our most commonly experienced emergency situations.

Be aware that the site is not monitored and you may not receive an immediate response from someone. It is in your hermit crab’s best interest that you read the articles linked below.

After reading these items if you still need some help, please locate the list of Emergency Help Questions. Copy and paste these questions into a new topic along with your answers and someone may be able to help you.

These questions were put together by Marie Davis in an effort to quickly identify known issues.
By answering ALL of the questions you will make it easier for us to help you. If we have to question you at length for details it simply delays the process of determining your issue.

Aggressive hermit crab

I purchased new hermit crabs: PPS (Post Purchase Stress)

Calibrating Humidity/hydrometer

Limb loss

Mites or pests within crabitat

Hypoaspis Mites are beneficial

What is Molting?

Is my Hermit crab dead or molting?

Preventing overheating in the crabitat

My hermit crab has left it’s shell and is naked

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by Stacy

PPS (Post Purchase Stress) Minimizing the Impact

February 21, 2013 in Biology, Caresheets, General

written by Sue Latell March 8, 2006

I have belonged to the on-line crabbing community for a little over 3 years now. From day one there was discussion about the number of deaths immediately occurring after purchase. It evolved into a named syndrome: PPS. Many “unexplainable” deaths that occurred in the time-frame from newly acquired to first post molt death were labeled PPS. Time lines wavered (anywhere from one week-up to one year), and alarmingly glossed over (in my opinion) too many other potential causes. The interesting aspect about this subject is that for all the debate that occurred, and the viable, if not absolute reasons offered, not one person or group was willing to agree or offer what to do to minimize it. What is more alarming about this is my own willingness to allow it to continue, even though I understand what PPS is! I think I have been maintaining PPS as an excusable reason for me to have a death in my population. It is important to me to be, or at least appear to be competent in the care of our charges. So grudgingly I have to admit that my complacency in not wanting to clearly define and action PPS, is so that I have a contingent reason to remain blameless for their death. It has been and is treated like this big mystery that there is no obtainable solution to! Well I think it is time to recognize what PPS is, as I am pretty sure we have had the answers at hand for some time!

The purpose of this article is to define what we know PPS to be TODAY; as we can understand its cause and is supported by the knowledge we have documentation for. We can amend standard care practices at this minute. That said, this definition should and will be refined as our successes and information on crabs grows. This is a first step to taking rightful responsibility for this type of crab death. There is a somewhat tested solution to this (if at this point, only by me) that I hope will evolve into an observed and practiced tactic. Please also refer to the companion article: “Refining the Purpose for ISOLATION”, for further clarification.

What is PPS?

PPS is the result of a crab’s inability to physiologically adapt quickly enough from his natural circumstances (environment and habits) into a transitional one and then into a captive environment. The inability to adapt is invoked and influenced by the degree of and withholding of elements the crabs need to adjust to their environment.

This statement means that crabs suffer the most risk of physical stress induced death from the change in their environment (heat, humidity, range and associated resources) by being harvested, shipped and housed by the pet merchants. Resources in this context are water, salt water, food and shelter. Explicitly we need to recognize that the stress is not an “emotional” one, which we have to tendency to relate more easily to. It is physical and involves their ability or inability to forage (for food); have access to resources such as salt water, fresh water; an appropriate substrate and/or room to metabolize to their new environmental surroundings (heat and humidity)! So what factors influence the potential for PPS?

Hermit crabs have remarkable stamina and can tolerate the extremity of their environmental changes for a certain amount of time. They also have built in metabolic processes that assist them in adjusting to their immediate environment. These include hibernation and respiratory regulation. These processes function when fueled appropriately by diet. Because they involve digestion and chemical adjustment, they take longer time to come into effect. Therefore, a rapidly changing environment can short circuit these process mechanisms. Another process, not quite of the same class is osmotic regulation. As long as there is physical access to water, crabs are immediately able to implement procedures to control temperature. This process is mostly reliant on water. A guide to understanding the time frame these processes can take for crabs to implement involves their initial health, their size, and how fluctuant the extremes are in occurrences and interval. All of these things by their very nature are aberrant! For example, a healthy crab can slow down his processes to accommodate a drop in temperature with minimal impact for about 7 days (the rough estimate it takes for a medium sized crab to ingest and process his last meal, plus exhaust immediate reserves). A lower humidity can also be accommodated in similar fashion. Water access does play a significant roll in this control mechanism, as well as for an over hot/humid situation. So if there is a lack of a key resource (water), or if the temperature they are kept at changes rapidly, they may be unable to sustain equilibrium for extended periods of time, especially if the crabs are not fed adequately. This inability does not immediately kill them, but the longer the duration of these types of events accrue, the more they become life threatening. This also explains why a crab may resort to cannibalism to survive!

The hardest part about determining if your crab may succumb to PPS is in the KNOWING if these circumstances were applicable to your crab’s journey to you. Well I can say with some measure of certainty that they would have had to endure significant change over at LEAST a 21 day period. That said, from some of the stories I have read on our forums, that time frame is modest! At some point in the future I will provide a more detailed accounting of what our crabs can go through to get to our pet stores, but for now let’s just focus on PPS.

Here is the really difficult point about PPS, and due to its nature, is probably the main reason we have continued to seek “reasons” outside of our control for PPS. Our NEW CRAB introductory practices! We pride ourselves on establishing and sustaining our interpretation of an “ideal” living environment for our crabs. Temperature and humidity are kept and monitored (by gauge) at the optimum levels (but not always in ranges>>bad, very bad). We for the most part provide the best in foods and offer both types of waters. Provide for hiding, climbing, digging, lighting; what more could our crabs possibly need and want in these circumstances? Why do they still die? Because we in our infinite wisdom think we have provided crab heaven! Well we missed an obvious problem. Not only have some of us taken on the belief that if we provide the right conditions crabs will recover just by what we provide, we have also ignored that crabs have the ability to adjust to their environment when they haven’t already been taxed to very extreme limits. This includes going from BAD environments to GOOD ones! We do not factor in what they have endured before getting to us, and we are quite strict in getting them into good ones as soon as possible. It seems that it is difficult for us even to conceive that we may be pushing them past their endurance level by moving them from that “Crab in a Cup” or dreaded mall kiosk, to a good crabitat set up.

Well in large part we are! We need to graduate them to the ideal conditions so their bodies and processes can catch up. How long can that take? Up to a month, and that is just strictly going by their ability to physically accommodate the change. What fuels that? Food taken in over time, waters and familiarity they gain in their surroundings. Then there is the possibility that they need to molt. Let’s hope they don’t have to for that first 30 day period. In my experience, molters that were new to my tanks suffered the greatest proportion of death! Death resulted 80% more then, than at any other time in my entire 6 year run!! The second month was a bit better at 30% death ratio, but after that it has (at least for me) been less than a 3% chance (at a 50 headcount) after 60 days.

So what are we supposed to do to prevent PPS?

Well while I am tempted to say that a procedure will “cure” almost all potential for PPS, it would be untrue. Since we have absolutely no control over when a crab is collected, or how long it has taken him to be collected, or have the experience to be able to with precision estimate at what point on the PPS scale an individual crab may be at, we have to generalize a treatment. We also cannot accurately factor in how people interpret heat and humidity, healthy diet and other handling aspects involved in overall crab husbandry.

So for the time being, PPS would be best addressed with a method that first allows for close observation by handlers, and secondly accommodates the crab’s ability to adjust to his immediate environment. So what does it take for these conditions to be utilized and what specifically does this mean?

The most important principal is GRADUATION of environmental conditions. Based on an average, calculated by scientists while they studied components of a hermit crab’s anatomical processes, they noted that it can take up to 96 hours for a crab collected and sampled directly from his native habitat to adjust to a change in environment. This is once the crab reaches his physiological threshold whereby hormonal triggers begin to occur. The hormonal regulation is fueled mostly by the crab’s food resources, but it also can include other regulatory systems. This means that a crab requires time to reduce physical stress by being able to adjust to his immediate circumstance. The greater the change, the less potential a crab has to adjust successfully, and co-dependent to time is the resources available to the crab either internally (through reserves), or externally in the form of food and water. Scientists have calculated that there is the highest successful adjustment when environmental changes occur in 5-7% increments. This means if they are adjusting temperature or humidity, they use the existing conditions as the constant, and use the percentage as the increment for adjustment. So how do we apply that to our method of introduction? By this:

1. Observe and recognize that your crabs are mostly leaving poor humidity and heat conditions. (Usually too high/low heat, and too low humidity) Also, food resources have probably (but not always) been limited, thus making the crab’s system “sluggish” and slow to respond to the change. See if they have had water vs. a sponge; note the approximate heat and humidity conditions and think of them in comparative terms to the ideal. Then establish a threshold (minimum tolerance level), that will be your starting point for readjusting crabs to the acceptable ranges.

This is not an exact process, because as you can already see, there can be several variables. I will provide an example, and after that I am afraid it will remain for the time being a function of trial and error, until we have more data in respect to successful outcomes. We will be measuring this by people providing key data that will be stored in a database. Once we tabulate “samples”, the increased number of samples will provide more accurate standards that we can provide as procedure to future situations.

2. We must utilize ISOLATION in a separate tank, where the environmental factors of heat and humidity is not PRESET at the ideal conditions. I have been concerned lately in the shift of thinking regarding the necessity of Isolation as part of the procedure for introduction. Far more focus has been placed on ISO being utilized for MOLTING. What I find frustrating about this, is that it is NOT necessary to do so in most circumstances. For re-acclimatizing stressed hermit crabs, it is! Please read the companion article “Refining the Purpose for ISOLATION”.

This is the sector where in the past I had remained flexible in terms of the duration of time we keep new crabs in isolation. That was when I was looking at it strictly from the perspective of general health and potential for bugs. What I was remiss in communicating, is that I have always as a practice kept new crabs in ISO for at least a month. In fact, it was rare that I move one to the main tank earlier even though they showed no indication of stress or contamination. The other important aspect of my ISO tank is that it is NOT at the same range in heat and humidity as my main population tanks. This was not immediately intentional; it came about from not being used! Why heat and humidify an empty tank?

Many of you already know that I do not advocate removal of pre-molt or molting crabs to isolation. So really my ISO has really only served as the transitional tank for new crabs, or as the treatment tank for sick ones. I think that initially this is why I had fewer occurrences of PPS, without knowingly doing it. My ISO built up to the ideal and equivalent main crabitat conditions over the period of time I kept them in ISO. I did not see the relationship until I consulted Peter about overheating issues and about dropped limbs. This was in early 2004. Principally what I learned about dropped limbs is that it was due to a stress induced shock caused by an extreme environmental change (that aspect was speculated and communicated already) and was just confirmed. The new information was that by controlling the extremity of the change, we would allow the crab to metabolically adjust less stressfully. It was outlined to me that changes in humidity and temperature should be gradually increased in percentage and in time to assist the crab. Or, at the very least , recognizing WHAT the differences in the crab’s initial environment were and adjusting the new conditions in relation to IDEAL conditions. I have shared this several times, especially when it was clearly explained by the owner how poor the previous conditions were. Consider this rationale: Remember reading at least once a story relating how a crab was able to survive DIRE conditions for up to a year and survive, only to die within weeks of being introduced to a “perfect” environment? Wouldn’t it stand to reason that the crab evolved to adjusting to his conditions to subsist in his environment if it occurred over an interval of time that his body could adapt to? Then we basically eliminated that interval to reverse the process, thus resulting in death. I saw immediately why this could be possible. Now you may understand too why I have been harping on maintaining “ranges” of temperature and humidity. It is because it can maximize the crab’s ability to adjust!

3. We must set a starting point for environmental conditions. If your crab comes from a pet store that has for example a heat lamp, no cover, no water, chances are that the approximate existing humidity range is 50% or lower. ASK how long the crabs have been in the store tank. If it has been more than 2 days, you will need to start at the lowest level that crabs can tolerate. That is 60% (with access to water and food), and a maximum tank temperature of 72 degrees. You would keep that level for a period of 72 hours and then increase it by 10% to 66%, and maintain that level for 72 hours, repeating the process until you match your main tanks average humidity level. This would take roughly 2 weeks if your target range was 79%. During this time crabs will need food to support the hormonal adjustment necessary to acclimate. Give them the fighting chance by not immediately moving them into a more competitive environment with your existing and healthier crabs! By sticking new crabs into a main population without benefit of isolation during their adjustment, you are diminishing the new crab’s ability to recover by increasing the resource competition level.

Temperature is not as significant to worry about; crabs use osmotic processes to control that! So their only need there is access to ocean salt water. It is the hormonally, or more accurately, the metabolically related processes that helps a crab adjust to humidity, and for that they need fuel and the time to process it. In effect this is how to minimize PPS.

Why is this not a fool proof cure?

This is the question that has held me back for some time. I wanted a definitive answer as to why PPS happened. It wasn’t until I looked at it in components that it became clear that while we can significantly reduce PPS, there will be circumstances that cannot be overcome. The ones I understand the most are:

1). Damage to gills from prolonged dehydration –

This condition thankfully is not too common, surfactants that the crab regurgitates from his digestive tract in order to self hydrate his gills, ultimately will result in death. There is nothing we can do if the conditions he endured drive him to this point.

2). Starvation-

While this seems to be one of the things we can combat more readily, if it has endured for a prolonged period of time, we may not be able to reverse the effects. A crab requires constant energy to sustain his metabolic changes. He may not be able to produce the necessary hormones to transition into his new environment. What’s imminently worse about this condition is that it can result in death for a crab that needs to molt, and remains a potential for causing molt death more typically, but not exclusively (depending on the crabs size) for the first few months of ownership.

3). Our humidity and temperature control-

Okay, I am prepared to deal with the flack I will get for blaming owners who fail to recognize the importance of maintaining temperature and humidity ranges. But there it is! There is an inherent mistake created when we relate heat and humidity in absolute terms! When we reply to inquiries with a comment like “set your heat and humidity to 80/80 and you can’t go wrong”, well, we do! While 80/80 is within the tolerable ranges, it does not communicate that these settings are the higher end of the range, and that there is and should be other temperatures and humidity levels within the crabitat. I realize that this occurs more out of a convention of speech and is not meant to mislead people. The sad reality is that people (especially new crabbers) take these stated levels literally and they worry and painstakingly try to achieve this exact ratio. What worries me about this is that we need to recognize AND COMMUNICATE that a crabitat should have RANGES of heat and temperature. The people saying that 80/80 produces active healthy crabs are not totally wrong (I just hate the way it is expressed because it gets misconstrued)…it is the “Way” it is interpreted when we use such an explicit example. We cannot show that the loftier areas will be lower in humidity but higher in heat…just like the middle of the tank will be closer to the true 80/80…and that the lower regions will be even more skewed temperature wise over the UTH (if there is one), below the lamp etc…so how can we communicate these acceptable ranges without creating a pseudo class that people use really by convention of speech and lack of full understanding how humidity and temperature work? It gets into dangerous ground when we say “oh Straws like the humidity at 85%”…well many of us do not segregate our tanks by species…and an E or PP may overheat when a tank is that over saturated!

I feel this aspect contributes greatly to crab death in general, and not just from the PPS perspective. Though it is related in the sense that we diminish our crab’s ability to adjust by not providing differences that our crabs can utilize! They are in a tank people! There is no comparison to their natural habitat where there is wind and tidal influences, ground cover, and the fact that they can move to utilize these resources at their whim, and instinct! We NEED to provide for that! I trust my own experience in this, and I admit I have never had an “unexplained” death 6 months to 1 year after getting them. So rather blatantly, I don’t think it is acceptable to define PPS over such a broad time-frame! I have had a couple of puzzling deaths, and I attribute it more to me not providing them with the proper foods, or the proper balance of adequate diet, and maybe even possibly poisoning them, than the soon to be dispensed idea that it is PPS! We need to call a spade a spade, or we are in danger of remaining blissfully, and BLAMEFULLY ignorant of real issues that we could resolve! I am ashamed that until a short while ago, I was willing to ignore the significant realization that WE are a component of PPS. I trust the results I have had over the years, and have now filled in the reasons (started by dumb luck, and now more understood) due to valuable information I learned from reading and discussing with experts the physical processes our crabs are capable of. Now it is time to use the information and change our methods!

So what will the new time defined extent of PPS related deaths be?

For now, until we amass actual numbers, I think my model that I accrued when taking in adopted crabs, and purchased new crabs will be used (a total of 117 over 2 years). That means that potential PPS deaths will defined for at least 30 days from original ownership date up to and including the first molt. This will be conditioned by the fact that if a molt occurs after the first 60 days (being the highest risk for PPS related death), then the death may be more attributed to a lack within the owners environment, not necessarily PPS. The factors used to qualify these latent molts will be crab size and review of the owner’s food list and environmental conditions!


PPS is Death as a result of a crab being deprived of the conditions and resources he needs to adapt to changes in his environment. We are part of that change. We can minimize PPS death by practicing ISOLATION and a GRADUATED increase to ideal crabitat conditions over a period of time to offset the poor conditions crab harvesting can create. These changes should occur in stages that the crab’s physical processes can accommodate. We need first to acknowledge the crabs own capability to adjust, and synchronize the environmental adjustments to their metabolic time frame. Death of a crab should not be classified as PPS outside of the initial established time frame of adjustment (30 days), unless there is a molt occurring within a 60 day time frame. After 60days, a case by case assessment should be done, and evaluated based on the crab’s size, on the conditions he came from, and from the examination of existing diet and environmental factors (heat and humidity). While PPS will be definite within the 30 day period, that likelihood in classification diminishes as time increases.

Implementation Recommendations:

This definition will be amended by statistical evaluation, and new study material. I recommend review in the process be conducted in 90 days time and that a committee be established in evaluating collected data. A permanent template with fixed element names should be used to feed the database for this data collection category: PPS.

Concurrent to this study, an evaluation of the specific accepted time frame for PPS to be considered a cause should be presented to crab care communities by poll. It should be encouraged that members also support their choice with their personal reasoning. This will then be used to help the committee establish the recognized and formally accepted time interval for decreeing PPS as the cause of death.

More articles about PPS:

Technique for Adjusting PPS Crabs
Comparative Example for PPS Practices
Preventing Death in New Hermit Crabs


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by Stacy

Refining the Purpose of Isolation

February 21, 2013 in Caresheets, General

writting by Sue Latell March 8, 2006

The Definition of Isolation

Isolation by very general definition, in the crabbing world means to keep crabs separated from each other in groups or by individuals by means of an object such as another tank. It can also mean that one crab can be isolated within a crabitat by an object such as a bottle or CD case, or piece of plastic. The purpose for this division is multiple. Most commonly, isolation has been utilized when dealing with crab illness, contamination, surface molting and more often than I like to see, molting in general. What ever happened to using it for NEW crab introduction? This was at one time, the main reason to have isolation. It was a measure to ensure a crab’s health and stability before subjecting him to competition in a larger population of crabs. This purpose will be my main focus! First let’s address some noted trends.

Current trends in applying Isolation Methods:

1). Naturalized Crabbing

I think that with the more specific advent of “natural crabbing”, we have lost some of the principals of why we practice isolation. Utilizing predatory mites has largely reduced the need to isolate contaminated crabs, and is one alternate method vs. isolation that I think makes sense (if you can afford it). One condition of the newer “natural” crabbing philosophy that I think bears further consideration is with respect to new crabs being introduced immediately into the main tank. While for the most part, it seems less stressful for the new crab to be introduced with a dip in the water dish rather than a bath (I agree with this), the immediate move to better environmental conditions does not allow for the potential issues surrounding PPS. Crabs that may have not been fed properly on their way to you, or crabs that endured severely inadequate heat and humidity, may more easily succumb to the PPS syndrome. This is because we are in effect increasing IMMEDIATELY the level of competition for food and space, while at the same time sticking him in new (if better) conditions for which he is not metabolically able to accommodate due to the lack of those resources. This is hard on the new crab because he more than likely is less “fit” than the existing crabs. A crab that has been deprived of food and water will have a slower metabolic rate making it very hard for him to adjust to a new environment (whether it is better or worse)!

2). Molting

It is with distinct distaste that I continue to hear how Isolation has been bastardized for the sole purpose of weeding out potential molters from some imminent “harm”. Mainly from what I hear (and personally cringe at) from “crazed blood-thirsty cannibalistic crabs”. Truly it is my intent to put to bed this wholly unreasonable belief. Crabs are not cannibalistic in the ordinary course of healthy existence. They are though opportunistic and will eat other dead crabs. I have requested from a biologist who had reported that the cannibalism noted in his field study (David K. A. Barnes; Quirimba Island, Mozambique, 1997) accounted for about 1% of a wild crab’s diet! I have written to him asking if he could specify the circumstances (if it was a molting crab cannibalized or what he constituted as cannibalism). His abstract did not allude to any circumstances. I have sent similar enquiries to 3 other reporters about cannibalism. But note, in each of these articles cannibalism is rated as a food source for less than 3% of the entire wild crab’s diet! As of yet, I have not received replies, and in one case the scientist has retired, and I am trying to locate some of his field assistants. I want this subject addressed! I will be writing an article about it once I have more information.

From the most current diet related behavioral understanding we have to date, if your crabs are cannibalistic, it is a clear indication that population ratios are out of whack with resources (space, food, and to a greater than realized degree, overall dietary components). Crabs specific competition behaviors are often misconstrued as aggression! This general misinterpretation makes crab behavior a fearful thing to identify in objective terms, and therefore hinders us from practicing appropriate solutions. It makes the most important process molting, something to fear. You should not fear it, but know all the related processes that influence molting. So really, there is no good reason to have to move a molter to Isolation unless you are not adhering to proper crabs per tank ratios. If you do not provide a well balanced and diverse diet, this may also potentially increase the likelihood of cannibalism.

I can see the rationale and merit of occasionally having to isolate a crab separately or within the main crabitat during a molt, but not always separate isolation! We should not be mainly fixated on telling people to isolate their crab because they are in danger of being attacked or eaten! While a crab may be consumed by another crab, it is NOT usually because another crab killed it! If we understand more clearly the behavioral habits crabs have, we would be already minimizing this type of occurrence!

Moving pre-molt crabs to ISO is far more stressful than leaving them where they are. Many times I see crabbers question why when they have moved their potential molter, it did not molt, and they want to know whether they should return him to the main tank (NO). Well, to just get to the point, it is because we more than likely arrest them from continuing! This is due to the change in environment. It may seem a subtle difference to you, but the crab if alarmed, will stop producing the molting hormone to switch over his metabolic processes to adjust to the new tank. This may take some time (possibly a week), or perhaps he won’t continue until he thinks his environment is stable; then if he is left alone, he may resume. The unfortunate situation in pre-molt is that it depends on the specific crab’s size and relative health on whether he can re-establish those different processes in a specific time frame we can measure.

I hope you understand what the danger is in moving molters. It is not the most efficient way of dealing with molting issues. I also assert that if we proscribed to a mandatory isolation period for NEW hermit crabs, these aggressive occurrences would become almost unheard of! I plan to outline this plan in detail.

3). Sickness

This is one of the most important reasons to have an isolation tank! It may not be viewed as such since there have been very few diseases or bacteria that have been identified for crabs. Of the most contagious class, there is shell rot. Thankfully there have not been too many occurrences of this. If a crabber does encounter it though, it is imperative to keep the sick crab separate from the main population! If a crab suffers an injury by fall or aggressive encounter, this is also a good place to put them for recovery.

One of the things about refining isolation use is to recognize that within our crabbing community not everyone has the same resources. If we streamline our usage of isolation, we can increase the degree of successful use, and the number of people able to do so by procedure. I have often felt bad for our young crabbers who are hard pressed to supply an adequate crabitat, never mind an isolation tank. With the way we utilize them for molting now, it almost stands to reason that we expect people to have 2 isolation tanks. One for molters and one for sick, injured or aggressive crabs. Again this is something I would like to streamline for better application. I think it is more reasonable and likely to have owners having one isolation tank.

4). Aggressiveness

Some people employ use of isolation for “aggressive” behavior. While not a bad idea in some cases, there is a very varied interpretation of what actually constitutes an aggressive act. This category will improve over time as people become more informed about what constitutes aggression.

Having helped my mother train dogs when I was a teen taught me early lessons in understanding animal behavior. Something I have studied really all my life on various animals. I think this natural interest in it helped me glean some of the finer nuances of what crab behavior is like. We have many kind and gentle animal lovers among us, and for them I think it is the most difficult to see the animal for what it actually is. Hermit crabs do not really have the ability to put “thought” to their actions. They are more imprints of instinctual behavior for a specific purpose. This does not mean that crabs do not have individual traits that make them unique from others within their species, but it is not like a mammal’s “personality”. If they are larger, healthier and stronger than another crab, they will exploit that to maintain their ability to select the best burrowing spot, feeding time, molting area. They use display tactics that warn off other crabs. Their behaviors are of a hierarchal order because they live within a social order. This means that the crabs themselves understand what the displays are about. We don’t always have that same understanding!

Crabs will posture in competitive acts for resources. These are for shells, space, and food. They may even compete for mating privileges, we just are not aware if that is true! In the wild these displays almost NEVER become life threatening, and it is rare for injury to occur. That said most species do not specifically intermingle in the same habitat. They may be found mingling within a niche, but each species will exploit their own areas. So really, when there is an enforcement of privilege occurring, we are really preventing the crabs from behaving naturally if we stop it. Even in inter-species skirmishes I have witnessed, it has never gotten to the point that a crab was hurt. Separation in most territorial disputes will not resolve themselves until the crabs “duke it out”, despite our separating them!

Aggressiveness almost always occurs due to pre-molt hormone imbalance. This imbalance can increase in severity if dietary deficiencies exist. Additionally, if the tank is overcrowded, the crab’s natural tendency to become more territorial during pre-molt may escalate to aggression if there isn’t enough space. If an owner is aware that their space ratio may be at the maximum level, then DO use isolation! Sometimes shell fights become numerous, instigated by a pre-molt crab. Though this behavior is not exclusive to pre-molt, it occurs more often in pre-molt and is incorrectly classified as aggression. As long as there are adequate shells for all crabs, this type of competition is usually minimal.

NOTE- a misinterpretation about pheromone odor on molters:

While it is true that a crab may secrete a pheromone when in molt, it is odorless to prevent detection by predators. While it may be recognized by other crabs of the same species, it would be the “mating” hormone that attracts their attention, and would basically be produced by females ready to mate and still soft. If your molters are housed separately from your main population for the duration of their molt, this would then single out your newly molted crab as a “newcomer” upon reintroduction. Crabs have a strong sense of smell, but their memory is not like that of a mammal. So they will treat the isolated and re-introduced molter as an interloper. We minimize this by utilizing the introductory bathing technique (not to get the “molting” smell off the crab). What I am getting at is that separation is again creating more of a potential for problems, than it is eliminating it!

Why a new approach?

This article is for the purpose of refining, or maybe I should say for redefining what ISOLATION should be used for. I would also like to review what the environmental conditions for isolation should be. And finally, for re-establishing isolation for new crabs and honing the isolation method to aid in reducing PPS type deaths. See “PPS: Minimizing the Impact”. I apologize if I appear to be mocking our current practices; I do realize that some of our crabbers have been able to succeed in the interchange between ISO and main tanks for molters, and I do not want to diminish the bad experiences some of our crabbers have faced. It may be necessary for some crabbers to continue using the isolation method for molters, especially if space and diet conditions are questionable. I have seen and heard that these occurrences still happen though. It seems to me that we just have not resolved this from happening efficiently. I think it is because our approach is wrong, and this is why I am mostly against some practices. Additionally, a good number of other crabbers, including me have not experienced the degree of issues surrounding molters, ever, even though we do not isolate them! So I surmise that it is the behavioral aspects of caring for crabs that we need to exploit to reduce molting related aggression.

I truly hope to swing your attitudes towards really utilizing Isolation methods for applications that will be ultimately of more benefit to our crabs. Let us begin then in refining this method for specific processes that would benefit crabs.

General ISOLATION utilization:

This is what I recommend the priority be for SEPARATE ISOLATION:

  • NEW/PPS crabs
  • SICK or INJURED crabs

A miscellaneous class for:

  • AGGRESSION (true and severe)
  • MOLTING anomalies (deformity, inability to shed, or new molting crabs)
  • MITE CONTROL, where use of predatory mites is not an option.


There are circumstances that can be addressed within the main crabitat instead of separate isolation. This would be done employing the “plastic bottle” method, or some other barrier that is appropriate for use in the crabitat. These would more commonly be related to:

AGGRESSION (territorial disputes, shell fights)
MOLTING (surface molts, ruptured molt sacks, disturbed molters)
DROPPING LIMBS (after initial NEW crab isolation, where crab has been already been moved to the main population from isolation)

Environmental Conditions:

The above divisions were created keeping in mind that there is usually only one isolation tank at an owner’s disposal. Therefore the starting temperature for the isolation tank should be room temperature, provided that it is not less than 72 degrees Fahrenheit. Humidity will be the variable element in this tank and the initial setting will be set at an established starting point based on the reason behind isolation. (These will be defined a little more clearly by class).

NOTE: Heat range is 72 – 84 degrees Fahrenheit.

Humidity range is 74% – 82% (you may have to start below this normal range)
You will be using these ranges as your guide as you increase heat and humidity in the isolation tank up to the AVERAGE range in your crabitat.

The preferred tank type would be glass, but a plastic kritter-keeper that can maintain humidity through use of plastic wrap is also acceptable. (Just harder to maintain) Here is a list of what you should have in the isolation tank:

– Humidity and heat gauges
– Fresh dechlorinated water, ocean salt water
– Appropriate substrate (may have to adjust depth for size of crab)
– Alternate shells of acceptable quality (no holes, not painted)
– Ground cover (plastic or silk plants, driftwood)
– Heat source (by UTH or light)
– Lighting (bulb or tube assembly)-they need 12 hours of light!
– Food (Use mostly natural or fresh food sources)

These items are pretty much utilized the same in your isolation tank as they are in your main crabitats. Now comes the tricky part of changing implementation styles. I was stuck for a while in how to express this with the least confusion and the most flexible usage. The best way I could come up with is to assign heat and humidity controls and isolation duration based on the class (reason) for isolation. Here they are again; in the order of priority isolation should be used:

New Crab induction and method to minimize PPS:

1) Temperature should be in the low range but not so low as to induce hibernation. You want them to eat and access water right away. So the bottom of the acceptable heat range is 72 degrees. This temperature, depending on your household will be very close to your room temperature. If your room temperature is lower, then you will have to use a UTH or light for heat. Over the duration of isolation, the heat will be increased. We are not too concerned about how quickly the heat increases to meet your main tank average temperature, but it should not go over the average of your main tank. You must also have ranges (hot, warm and cool) within the tank, and ocean salt water deep enough for your crabs to easily fill their shells.

2) Humidity is the main worry here. While your crabs may have been in over hot and under humid conditions, you do not want to start humidity too high. This is especially the case if you have rescued a crab that has already lost limbs due to stress or is very sluggish at the pet store. The lower temperature will help him readjust simply because he is not using resources to stay cool. Start the humidity about 10% lower than the normal low limit, so that he will slow down his metabolism that is not overtaxing his system. Keep this level for at least 48 hours. Hopefully he will smell the food and eat. Once he has eaten once, you can begin to increase the humidity every 3 to 4 days at 5 -10% increments. If they bury, do not increase for a day or 2, just to see if they come up. You want the change to be gradual enough that they will continue to eat rather than immediately bury. The more they eat, the more likely they can get their system to adjust.

Here is an example:

Crabs purchased were in a hot tank, no water, just a sponge and sporadic spray bottle misting. They have to the clerks knowledge been at their store for a week. They feed the crabs commercial pellets.

1. You can assume that they are dehydrating. So you will be starting your tank at 72 degrees for temperature, and 60% for humidity. This probably can be achieved by setting up the tank the same day you bring home the crabs. Bathe them in dechlorinated water and then put them in. Have fresh foods in there. Coconut, honey and some fresh form of seafood (shrimp, krill, silverside). These are all metabolic fuel. Do not keep them in the dark. Make sure you keep up a 12 hour light regiment.

2. 3 to 4 days later increase the humidity to 70%. If they remain active and continue eating, you should be able to increase the humidity by 5% hereon. Therefore your next increment will be 70 x .05 = 3.5 so 70+3.5=73.5. You can continue increasing it every 3 or 4 days. Now, here’s the thing. If your crab is fairly large, you should slow down the increase interval. So for this example you may want to adjust the interval to 4 to 5 days instead of 3 to 4. Follow? (I know this will raise many questions) I can’t be more specific, other than to say that the crab is able to adjust metabolically with food as fuel and time. Size does affect the rate of metabolizing, which may mean that they can either do it faster or slower than the rate of change we are using; generally it takes them 72-96 hours or 3 to 4 days.

3. The duration of isolation I have assigned a general 30 day period for. I have done this for two main reasons. The first is that for small to medium sized crabs, the adjustment period is only about 2 to 3 weeks long. All of the adjustments occur within the 30 days. The second reason is that it provides enough time for your new crabs to eat and restore strength while competition for resources is limited to those in the ISO. Also if your new crab chooses to molt within the 30 day window (the most dreaded time) you can keep closer tabs on it! You also have the option to keep them in here longer. This is if they spend too much time buried. They may do so because the increase was too much for their immediate capabilities, that’s why you really do not want to continue increasing the humidity unless you see them eating and moving about on the surface.

Many owners are tempted to move their new crabs to the main population as soon as possible. This is a judgment call owners will have to make. There will certainly be those lucky crabs that had swift transfer from the wild to a caring pet store with satisfactory conditions. If your crab is one of those, by all means do what you feel is best. I personally think it does not hurt to ensure my new ones have the opportunity to “beef” up before facing new competitors in my main crabitats.

Sick or Injured Crabs:

When you have a crab that is “sick” we would qualify this by these conditions, an injured crab should be obvious:

– The crab shows some physical ailment like shell rot (dark scaling on exoskeleton in conjunction with concave depressions in the chitin)
– Listless and inactive outside the norms of what can be expected if he is in pre-molt. (No other sign of molt)
– A crab that is dropping limbs and has been a steady inhabitant in the main tank for more than 30 days

The recommendations I have received from a vet for treating fungal or bacterial infections on crabs is moderate temperature and lower humidity. See “Treating Ailments FAQ”. Therefore the isolation tank can be in the lower to moderate ranges. You do not want to stress the crab from too significant a change so if your main crabitat conditions are typically kept at the higher ranges you may want to do an in-tank isolation until you can adapt the isolation tank to suit the situation.

Miscellaneous Isolation:

Everything else mentioned above except for the named isolation reasons fall here. This is where there is a fine line to be drawn on whether you want the environment to be different than that of your main crabitat. Usually in this category you do not want to vary from the ranges already maintained in your main crabitat. Aggressors that won’t leave other crabs alone and have physically picked up and swung another crab around can be put here. They are most likely in pre-molt and if you move them you may interfere with that process. For this reason, you need to be reasonably sure that this can’t be handled within the main tank. If you feel it is necessary, then try to match the conditions between the two tanks as best as you can.

Well this is the general procedural advice I can recommend. I think there are so many different tank management issues, it is impossible for me attempt to recite them all. I might miss one or stress one more than another and raise too many questions without meaning to. There is just so much surrounding this. If this seems too vague, I did it more out of trying to accommodate everyone’s styles. If you have questions that are specific to what you practice, and you see no referral to them here in this article, I would be happy to address them personally. You can contact me at sue@coenobita.org, and I will be happy to assist you! Please contact CSJ staff for assistance.

Article: Refining the Purpose of ISOLATION ©2006, Coenobita Research

Written by: Susan Latell
Last Edited: 3/09/2006
Copyright © by Coenobita.org All Right Reserved.
Orginally Published on: 2006-03-09 http://coenobita.org

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