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Profile photo of Stacy

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


Profile photo of Stacy

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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by Stacy

Comparative Example for PPS Practices

February 21, 2013 in Biology, Caresheets, General

written by Sue Latel March 8, 2006

Little Billy has had 3 hermit crabs since his 12 birthday. He has a 20 gallon tank housing his 3 small PP crabs. One day when he is at the store picking up some ocean salt water for his crabs, he spots a tank containing 2 poor little Ruggies that have no water except for a damp sponge, huge pellets of food that he doubts they have even attempted to eat, and no ground cover to protect them from the 100 watt heat lamp that is shining directly on them from an open tank top. Billy has been a very conscientious crab owner. He explored on-line information on how to care for hermit crabs and has all the bells and whistles to keep his crab people happy. He has proudly seen his crabs molt, grow and prosper for the past year. Billy knows that the little Ruggies will not last long in the current conditions they are in. He consults a clerk, advises her of the poor crabitat conditions, and notes that there will likely be no changes made based on his advice. Billy’s mom is a sweetheart and lets Billy rescue these poor crabs from their sorry condition. Billy finds out from the cashier that those are the last ones from their shipment last month, and now they can order more. (God forbid). Billy provides his new crabs with a dip into his tanks water dish, and then they scurry to hide in the handy cave he has for his crabs. Well, a week later, and Billy has still not seen his new crabs. He doesn’t think they have even been to the food dish. He isn’t too concerned since they are likely de-stressing in the wonderful conditions in his tank. Well a couple of more weeks pass. Billy thinks he seen one of his new guys in the water dish, now there is signs of digging, this crab must be molting. Well another couple of weeks lapse, and it is now high time to do a deep clean. Billy carefully digs around to see if he can locate where his crabs may be down molting so he proceeds cautiously. Billy takes out some of his plants and shells for rinsing, he has found the top of one of his new crab’s shells, he checks to see how the little guy is faring and discovers that it has died. Billy is heart broken. Finally the entire tank is unearthed and Billy discovers that neither one of his new little ruggies made it!! That darn PPS, it is just not fair!

Same example, but now in context of enlightenment of the PPS solution:

Little Billy has had 3 hermit crabs since his 12 birthday. He has a 20 gallon tank housing his 3 small PP crabs. One day when he is at the store picking up some ocean salt water for his crabs, he spots a tank containing 2 poor little Ruggies that have no water except for a damp sponge, huge pellets of food that he doubts they have even attempted to eat, and no ground cover to protect them from the 100watt heat lamp that is shining directly on them from an open tank top. Billy has been a very conscientious crab owner. He explored on-line information on how to care for hermit crabs and has all the bells and whistles to keep his crab people happy. He has proudly seen his crabs molt, grow and prosper for the past year. Billy knows that the little Ruggies will not last long in the current conditions they are in. He consults a clerk, advises her of the poor crabitat conditions, and notes that there will likely be no changes made based on his advice. Billy’s mom is a sweetheart and lets Billy rescue these poor crabs from their sorry condition. Billy finds out from the cashier that those are the last ones from their shipment last month, and now they can order more. (God forbid). Billy goes home and sets up his 5 gallon glass tank to ISO his new crabs. They need help to be able to recover from those horrible store conditions. Billy asks his mom to help check his math. He figured that the crabs were in very hot and dry conditions. He needs to keep the room temperature at 72 and boost the humidity to a bit over 60% for the next couple of days. He puts in a dish of ocean salt water, and a dish of regular dechlorinated water and a big fat chunk of coconut dipped in honey and sprinkled with bloodworm and spirulina. A few days later, he increases the humidity to 70%, he keeps the water filled up and notices there has not been too much food eaten. Oh well, he throws in some fresh apple and sprinkles it with some brine shrimp and hopes for the best. Well a few days later he increases the humidity up to 75%, this in large part by placing some soaked moss into the tank. Ah, they are eating some. Billy opts to keep the humidity at 75% and see if they continue to eat. Billy sees that they are starting to go more to the food dish. He tries them on some avocado and a silverside head. A few days later Billy adjusts the humidity up to 79% (which happens to be the RH midrange for his 20gallon tank), but there just is no crab to be found. So he checks on them a few days later, changes over the food, keeps tabs on their movement. Into the third week, he notices that more food is disappearing! He is glad since he was worried that they may not make it. He is going to let them stay in the ISO for another good week, just to make sure they keep eating well! Well about 5 weeks pass, and Billy wants to see his new crabs enjoy the main tank. Whoa, one of the crabs molted, and he is alive, yahoo!

Ok see the subtle difference?

This is one scenario. There are many others, and this includes crabs who do not suffer from poor conditions. Ultimately it is up to the crab owner how to proceed. The important thing to stress is that the responsibility lies with the consumer (purchaser of the crab(s)) to gather and observe as much information as possible about your pet’s existing living conditions as compared to what you will be providing them at home. This information will be the foundation of how you can implement a strategy to get them through the critical hurdle of PPS.

Once a committee has had the opportunity to hone the procedural aspects, and provided the accepted time interval for defining PPS deaths, we will try to specify more clearly a procedure to follow.


Copyright © by Coenobita.org All Right Reserved.
Originally Published on: 2006-03-08 http://coenobita.org

More articles about PPS:
PPS Minimizing the Impact
Technique for Adjusting PPS Crabs
Comparative Example for PPS Practices
Preventing Death in New Hermit Crabs

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by Stacy

Handicapped/limbless/sick Hermit Crab Care

October 16, 2012 in Caresheets

Written by Marie Davis (aka ladybug15057)

During a crabbers crabbing experience one may find themselves faced with a situation of needing to care for a severely handicapped or mutilated hermit crab. Do not despair, it is possible to care for a him so he can regenerate his missing limbs in hopes of having a successful molt. To do so will require extra TLC, time and patience.

First, one needs to have an isolation tank set up. The isolation tank should have a humidity level of 75-78%. (or the same percentage as the main tank humidity level was, unless this hermit crab is new and possibly suffering from PPS, which one would want to adjust the humidity level and temperature of the isolation tank according to the Post Purchase Stress article

Within the isolation tank place a dry sand substrate to limit the possibility of a mold complication in case the hermit crab would have any left over food on his shell or body after feeding. If this is not possible, one can get a small cleaned bowl and place dry sand within it and push this down into the original substrate in the iso, but should be large enough one can place a hut over the bowl. (or get a Tupperware type lid, a clean margarine lid and place dry sand within it) Do not use dry coco fiber, eco earth or a substrate that does require to be used damp so not to pull moisture from the hermit crab. Make a small impression within the sand to place the hermit crab in.

The isolation tank should have a regular night and day cycle up until one notes the gel limbs becoming larger and formed. When this is noted, the handicapped hermit crab should have darkness so his molting hormones can kick in. This can be accomplished by placing cardboard, or a towel on the outside of the tank.

Carefully attempt to offer him a drop of honey which is natures natural antibiotic. Next, with a dropper if possible, gently take the hermit crab and place 1 drop of dechlorinated ocean/sea water with 1 drop of dechlorinated fresh water within his shell. (if the hermit crab is larger, the size of a 50 cent piece place 2 drops of ocean and 2 drops of fresh water within his shell) After placing the drops of water within his shell, carefully place him in the sand impression you made and cover him with the hut. If he had molted, place his exo within the impression in the sand with him. Leave him be to destress for at least 12 hours, or until the next morning.

If he is limbless he will need your assistance in eating, as well as providing him with the water he needs. After permitting him to destress, take part of his exo and crush this into a powder form. Take a drop of 100% pure honey and mix a little of the exo within it to make a mushy paste. (If he hadn’t molted read regarding foods to offer later in this article, also making them into a mushy paste type food) Once the exo/food is prepared have a place ready where you can sit to take the time needed to feed him. Use a toothpick, or something small that you will be able to control easily and place a small drop of the mush on the end of it. Gently and carefully place the food where his maxillipeds (mouthparts) are and wait patiently for him to begin to eat the food. If he shows no interest in the food, you may need to gently touch his maxilliped area with the food to get his interest for him to begin to eat. If you watch closely you should be able to tell when he has had enough to eat, so stop offering the food so not to stress him more than he already is. (this is normally after he has cleaned the toothpick twice from the food you’re offering if he is a smaller hermit crab, if he is a larger hermit crab it maybe after 3-4 offerings) If you have gotten any of the food on his shell, clean this carefully with a Q-tip and ocean water. Once you have cleaned his shell of any possible food, you can place him within the ocean water pond for a minute to see if he can fill his shell with some water.

(make sure he is not totally submerged, and this can vary, if you place him in the fresh water pond for rinsing, place 1 drop of ocean water within his shell when you remove him from the pond, if you place him in the ocean pond, place 1 drop of fresh water within his shell) Once rinsed, place him back within the isolation tank in the area you had prepared for him and place the hut back over him. Please do not disturb this hermit crab again until evening when you have time to attempt to feed him again. The less he is disturbed, the less unnecessary stress he will have to undergo while he feels in such a vulnerable state. For the evening feeding, make a mush out of his exo with dechlor water. For the morning offering you can mix the crushed exo with dechlor water with a little spirulina mixed in as well if you have any. Attempt to rotate this with each feeding until majority of the exo is gone so he hopefully will continue to eat since hermit crabs are known to ignore foods they had eaten within 9-14 hours before.

Once his exo is gone, the feeding must continue on a daily basis in the morning and the evening as well as the cleaning of any excess food off of his shell and the fresh/ocean water dips in the pond. At night prior to you retiring for the day, place 1 drop of ocean and 1 drop of fresh water within his shell so he will have the water he wants/needs.

It is very important to offer him wide varied, high quality diet. Please attempt to stay away from the commercial foods unless they are of higher quality and either freeze dried or dehydrated without any preservatives within them. Offer foods that contain copper, lipids, zeaxanthin, bete carotene, high protein source, a high calcium source, chitin, cellulose, spirulina, seaweed, omega fats, Carbohydrates, etc.

The above care is provided for a hermit crab who has no limbs and not able to move about himself. If your hermit crab has a 2-3 limbs or more, you may wish to alter some of the care advice above. Observe him closely to see if he is able to go to the food dish as well as the water ponds on his own. This can be done too while you are asleep or away by smoothing the sand and checking it for tracks in the sand. If he is able to move about on his own, the detailed care above can be adjusted accordingly.

If you need further assistance, please feel free to complete the Emergency Questionnaire and post it on the forum.

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by Stacy

Checklist for Regular Care and Maintenance of Your Hermit Crabs and the Crabitat

September 27, 2012 in Caresheets

Originally written by Vanessa Pike-Russell

After your crabitat is set up you will have to maintain it and your crabs. Below you will find a list of what tasks should be done daily, weekly and monthly.


o Refill fresh water dish and the ocean water pond
o Empty and clean the food dish (no chemicals)
o Offer a different food each day
o Rinse sponge in water free of chlorine
o Check the humidity level is within range (50-60% or relative humidity 70-80%)
o Check the temperature of air and substrate (21-27oC or 70-80oF) and that it is stable


o Clean the bowls and dishes (without chemicals)
o Pick through the substrate for food and feces
o Give your sea sponges a good cleaning , squeeze to get any stagnant water out and leave to dry (for long life)
o Sterilize (boiling) seashells and re-offer them to crabs


o Where needed, remove all items from tank (substrate, wood, toys, dishes etc) and clean by boiling or baking
o Wipe down walls of tank with vinegar and water, or ocean water mixture. (Avoid cleaning chemicals eg. bleach)

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by Stacy

Identifying and Addressing Aggression in Hermit Crabs

September 27, 2012 in Caresheets

Originally written by Vanessa Pike-Russell

Behaviour in the Wild

Hermit crabs in the wild

Hermit crabs in the wild

Land hermit crabs are territorial animals, and as such they will often act aggressively towards one another to establish a ‘pecking’ order among their colony. Sometimes this can be in the form of ‘feeler’ or antennae fights, others in violent pushing or flicking fellow tank mates out of the way. Usually this is not serious enough to warrant intervention. However, some hermit crabs will act in a manner that is harmful to other hermit crabs, often trying to pull their hermie buddy out of a desired shell, or attacking eyes, antennae, claws, legs or abdomen.

If you witness behavior that may be harmful to one or more hermit crabs, it is important to separate them until the aggressor has settled down. Sometimes tank aggression can be a precursor to a molt, or the result of being picked on or bullied in the past. The most common form of aggression is where one crab tries to pull their tank-mate out of the security of the seashell.

Handling with Respect and Gentleness

Holding hermit crab

Gently holding a hermit crab

It shouldn’t be forgotten that hermit crabs are not toys, but living animals. It is important to pick them up gently, carefully and talking softly to them to let them know that they are safe is often a good idea. Use slow and gentle movements and always remember to carry them steadily. If you were placed on a palm and thought you were going to tumble off the edge, what would you do? A hermit crab doesn’t have hands with fingers, it has claws and legs. In order to save itself it will grip on with what it has available, so remember to help your buddy know he is safe from harm and put yourself in the place of the hermit crab at all times. A hermit crab treated with respect and gentleness will be gentle. A hermit crab that is handled roughly and with anger or haste will soon let you know that he can be just as crabby!


Hermit crab with gel limb

Hermit crab with gel limb

In the wild a hermit crab will “throw” a claw or leg if another hermit crab tries to pull them out of their shell. This is a responsive behaviour and their limbs are built in a way that they are able to “drop” or “throw” a limb easily so they may survive an attack. This is called Autonomy.

Normal Behaviour

Tumble Time

Gentle sitting on Jimmy

Gentle sitting on Jimmy

You may see your hermit crabs climb over the top of each other, or perhaps flick each other out of a prized spot or corner. This is natural behaviour, and doesn’t normally harm your hermit crabs. You may have watched puppies or kittens playing and vying for the best spot near Mummy dog, ‘rough-housing’ and play fighting. The flicking and tumbling another hermit crab out of the way is just in the nature of the territorial hermit crab and helps to establish ‘pecking order’ amongst hermit crabs.

Stridulation (Chirping or croaking)
Hermit Crab Chirping Croaking
(click to play!)

I was doing some reading of my “Biology of the Land Crabs’ book today and came across a chapter on stridulation behaviour in land crabs. Of specific interest was a paragraph on Coenobita:

“Stridulation in conjunction with posturing is common in aggressive displays of Coenobita (Hazlett, 1966; S. Gilchrist, unpub). Clicking by rapping of appendages together and by tapping the shell are integral parts of aggressive encounters of C. clypeatus and C. compressus. When alarmed, Birgus latro briskly stamps the second peripods. At other times, even when not apparently alarmed, this crab produces continuous clicks (Grubb, 1971). This may be a proximity warning to con-specifics.”

[ Reference: page 130 from Biology of the Land Crabs. Edited by Warren W. Burggren and Brian R. McMahon. Published in 1998 by Cambridge University Press.]

I have other references which I will dig up (literally, its all in storage) and share. From personal experience my hermit crabs mainly chirp when there is another crab bullying them. Prime example was when I heard ‘rheet rheet rheet’ and went over to the tank, saw one crab over the top of another one and trying to pull the poor crab out of its shell! I’d be making a lot of noise too! Some crabs have chirped or croaked when being picked up, but very rarely. It reminds me of a car alarm – sometimes its a false alarm, other times it means something is wrong.

Antennae Fencing

Antennae war

Antennae war

Another thing that hermit crabs like to do is to go up to each other and have a hermie ‘antennae/feeler wiggling and touching’ encounter. You might see the antennae moving quickly, and brushing against the antennae of the other hermit crab. This may take a few minutes to die down, and either crab lose interest. Sometimes it is almost as if they are talking in code, giving signals to each other. As long as they are not hurting each other, it is often best to let them interact and develop their social skills with other land hermit crabs.

Cautionary Behaviour

Cheliped Clashes

Sometimes they may even brush cheliped, grasping claw, against each other. IF this progresses into an entirely aggressive act, such as trying to sever antennae, limbs, eye stalks or removing the other hermit crab from its shell, THEN it is time to ‘break it up’.

Shell-based Aggression

Shell change animated

Hermit crab shell change

When one crab likes another’s shell, say Crab A likes Crab B’s shell, Crab A will go up to Crab B’s shell, knock its shell ( that of Crab A) against the other crab’s shell (Crab B), causing the crab in the desired shell (Crab B) to come out and have a look at what is going on. Now the first crab will try to pull the second crab out of its shell by a cheliped or other limb. The second crab will normally drop his cheliped(grasping claw) or leg/s and retreat inside his shell, using his remaining cheliped to protect himself. Preferring to loose a limb instead of loosing a shell.

If there is a shell involved, it often helps if you place the attacker into a container with a number of suitable shells in different sizes, shapes and weights. It could well be that your hermit is crabby because his shell is too small. Imagine if you had to wear shoes two sizes small or large for you, and you were stuck in a glass tank and not able to go shopping to find a new one. What else could you do, but fight for the best shells with your tank mate. Remove the source of the aggression, and you will have relative peace and happiness in your crabarium.

Deadly Behaviour

If you don’t remove the cause of the stress, you may just find that your overly stressed and crabby companion has ripped another hermit crab out of its shell, or viciously attacked it. If this happens, it is time to re-evaluate your crabitat and seashell collection, but first isolate the aggressive hermit crab and give it somewhere comfortable, equipped and containing an area it can retreat within darkness.

Somewhere Dark and Private

Hermies n Herps rock shelter

Hermies n Herps rock shelter

It is important that you have several spots within your tank for your hermit crabs to retreat within to escape the stress of life in captivity, mostly in partial darkness or protection from other hermit crabs. The most popular forms of tank decorations that meet this need are the Rock Caves, Coconut Huts, Hideout Dens, Terracotta (clean) flower pots, and more. Just like reptiles and many other animals, hermit crabs will be significantly less stressed if they believe they are protected from predators and allowed some cover of darkness.

Some Strategies
Over the past seven years I have had a handful of hermit crabs that were dangerously aggressive to their tank mates, and each time the best remedy was:



1. isolation
2. dark and private, quiet
3. access to more seashells
4. slowly building up a sense of trust with the hermit crab, through talking and treats
5. observing the hermit crab with others at bath time or on supervised visits to the crabarium
6. if there is still a problem, re-organizing the crabarium and allowing all the hermit crabs to play outside of the crabitat for a while in neutral territory (such as the weekly buffet container).
7. rotate the seashells within the tank, so that the hermit crabs think they are getting new shells, so they will check each out — which may spark a vacancy chain massive seashell swap.

Larger Crabitats = More Space + Less Stress

If you are still having problems then it may help if you separate the crabs into two tanks, or upsize to a larger tank if needed, with a barrier. Most of the time people use a 10 Gallon or 20 Gallon LONG tank, which has very limited surface area. If you buy a larger tank, perhaps get one custom made. It is often cheaper due to the thinner base — no need to have the thickness due to heaviness of water in fish tanks. If you can’t afford this, it might help if you exercise your hermit crabs in a large, clean storage tub or other plastic container for a few hours a day (weather permitting).

Photo Credits: Travis Wease, Vanessa Pike Russell, Stacy Griffith, Michelle Stephens

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by Stacy

Hermit Crab Essentials Shopping Checklist

September 27, 2012 in Caresheets, Crabitat

Originally written by Vanessa Pike-Russell

Hermit crabs are advertised as cheap and easy to maintain, which is not necessarily true. To keep your hermit crabs happy and healthy, you will need to provide a lot more than food and water.

The following is a list of the essential items your pet hermit crabs will need:

Essential items for optimum land hermit crab care

Glass tank with lid:

A glass tank is preferred over plastic tanks, which will scratch and will not be able to hold the humidity within the ventilated lids. A glass lid on a glass tank helps keep the temperature and humidity within hermit crab’s habitat, allowing for a slight gap for airflow. This airflow of fresh air into the humid environment will help to cut down on mould and bacteria, which can cause illness and even death among hermit crabs, often detected by a musty or ammonia odor.


Substrate is what we call the material that lines the bottom of the tank, and creates the ‘beach’ within your crabitat. The most popular substrates being: sanitized beach sand; silica dust-free play sand; fine river pebbles (such as Australian Pet Supplies or Estes NaturalStone); crushed coral; and coco fiber bedding sold in compressed bricks. You will need enough of a depth to cover your largest Land Hermit Crab; often twice the height is sufficient for them to bury.

Under Tank Heater:

An Under Tank Heater or U.T.H. is a heat pad made especially for small animals and reptiles. Popular brands are: F.M.R. (US-only), Four Paws(U.S.); PetZone (Australia); ZooMed(UK/Aus and US versions). An U.T.H. is used to keep the hermit crabs warm by gently warming the glass floor of the tank, in turn warming the sand. You may need a thermostat to regulate the warmth of the sand at the glass level within your tank if the artificial heating temperature rises above 26oC or 75oF.

Overhead light:

Hermit crabs require normal cycles of day light and darkness at all times. An overhead light can also be used to warm the tank in place of an UTH. If you want to use the light as a heat source be sure to get one that had two fixtures so you can use a day bulb and a night bulb. Or use in conjunction with a UTH and a thermostat so that your tank temperature does not fall too low at night. Reptile bulbs are recommended. A bi light hood placed on timers makes easy work of controlling the light cycles in your tank.

For more on lights visit: Using Lights to Keep Them Warm


You will need at least three dishes: a fresh water pool, ocean water pond, and a food dish, non metallic.


Your Land Hermit Crab has been used to a varied diet of foods and needs a mixture of ‘meat and vegetable’ type foods, such as the commercial pellet types, as well as staple dried foods that will not perish as quickly as the fresh foods they need on a regular basis. A sample diet may be a dish with ground Aussie Hermit Crabs Pellets, a sprinkling of Tropical Banquet, and a scallop shell with fresh food such as grapes, rice, fish or vegetables. Try to alternate the food types and offer small servings to avoid spoilage.

For more on foods visit: Hermit Crab Cuisine


A thermometer is used to observe the temperature inside the tank. Thermometers come in three main types: the adhesive fish tank style, based on a sticker that changes colour as the temperature at the glass raises; the circular reptile-type thermometers which are based on a coil which contracts or expands; a digital gauge which uses a probe and allows you to measure the temperature at more than one location.

For more on substrate temperatures visit: Substrate temperature V air temperature


A hygrometer is used to observe the humidity inside the tank. Just as with temperature, humidity is very important. If the humidity drops and the air is dry, your land hermit crab will have difficulty in breathing through their modified gills, which act as lungs when moistened and correctly functioning.

Read The Importance of the Right Kind of Salt
For help on mixing ocean water visit: Mixing Ocean Water

Extras – Optional extras

Mister Bottle:

A mister bottle produces a fine mist of water, to moisten the hermit crab’s gills. You may know them as facial misters.

Water Glass, Marbles or Glass Pebbles:

Great to use in deeper water dishes to enable crabs the traction they need to get in and out, plus acts as a decoration.

Sea Sponges:

Natural Sea Sponges are added to the water dish to provide humidity and moisture within your tropical crabitat. Place one in your water dish to minimize spills and maximize humidity.

Plastic Plants and Vines

There are many types of plastic or fabric plants and vines which can improve the look of your crabarium, as well as to add entertainment for the crabs as they climb over, hide under and travel among the greenery. It is a good idea to create some dark spots in the tank, but be careful that they can’t climb out!

Shopping Checklist


  • Tank
  • Lid
  • Substrate
  • Gauges (hygrometer and thermometer, look for adjustable ones)
  • Dishes 2 for water, you can use scallop shells for food
  • Heat source
  • Light source (can be your heat source also)
  • Food
  • Ocean salt for making ocean water
  • Dechlorinator
  • Shells
  • Furniture (for climbing and hiding)


  • Mister
  • Water glass, Marbles or Glass pebbles
  • Sea Sponges
  • Plastic Plants and Vines
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by Stacy

Bathing your Land hermit Crab

September 27, 2012 in Caresheets

Originally written by Vanessa Pike-Russell

It is important that your land hermit crabs are able to bathe themselves. Bathing allows your hermit crab to re-hydrate, flush out the feces and wash off the sticky juices and food stuffs which are present when you offer fresh fruit, seafood and commercial diets.

Active or Passive Bathing?

Passive bathing is when you provide the means for your hermit crabs to bathe, and allow them to bathe when they want to. Many passive bathing method crabbers will provide a deep fresh and brackish water ponds that their hermit crabs can wade through and bathe themselves in a “hands off’ method.

Active bathing is when you provide the means for your hermit crabs to bathe and actively encourage them to bathe. If you do not have a large crabitat and the room to put fresh and brackish (ocean water) water ponds or pools in your crabitat, you may wish to use a clean plastic container or tub and bathe them out of the tank.

Baths should be performed under supervision, and there are some safety measures you need to follow. It is important that the water you use is tepid or lukewarm. Cold or warm water can stress your land hermit crab. Land Hermit Crabs can drown if submerged in water for an extended time (fishermen say around an hour), but they have been observed bathe themselves in shallow pools when in the wild.

Hermit Crabs urinate through their antennae, so any water spills during handling is shell water. Hermit Crabs have an anus located on the end of their abdomen, and have been observed to flick any wastes (droppings) out of their shells. These feces are often brown colored and look like small sausage or ball shapes which consist mainly of sand and undigested foodstuffs.

When bathing actively it is recommended (but not essential) that you add a drop of Stress Coat with Aloe in the bathing water. It is a water conditioner which will remove Chlorine, Chloramines and heavy metals as well as creating a ‘slime coating’. to protect the delicate gill area. Stresscoat should not be used in water that has already had a dechlorinator added to it. The Aloe Vera will help them re-hydrate and condition their exoskeleton, “Aloe Vera, Nature’s First Aid Plant”. To learn more about Stress Coat with Aloe, click here.

Methods of Bathing

Submersion (active)

Sometimes it helps to gently tilt the hermit crab upside down, by the time they upright themselves air-bubbles lift from inside the shell, along with a gentle movement in the water to dislodge any gunk or mites which should float and be scooped out. I do not use the submersion method unless I believe there is a reason, such as decomposing foodstuffs, feces or mites. It can be a little stressful for some land hermit crabs, so you might prefer to follow one of the more gentler methods of bathing.

Leg Kicking (active)

Lower the hermit crabs into a ‘bath’ container such as a clean plastic tub or commercial product such as the bowls pictured above. The hermit crab then wades through the water and after a few laps they are taken out. This method should be done under close supervision, especially if the container used as a ‘bath’ does not include a section for the hermit crabs to be able to climb out onto ‘dry land’ after making their way around for a few laps for some solid ‘leg kicking’. I recommend this method

Drying Off (active)

If you choose to bathe, it helps to set them down into a drying-off tub or container lined with fresh substrate, clean towel or other substance for traction and allow the hermit crabs to walk about and drip dry. If you placed them directly within the crabitat, you would find that it would soon be water-logged from all the excess water from within the seashells of the freshly-bathed hermit crabs. The substrate should never be wet, only damp. Wet substrate with foodstuffs can create a breeding ground for bacteria and fungus.

Walk through (passive)

If you do not feel comfortable with either the submersion or wade-through methods of bathing, an alternative method is to provide your crab with the opportunity to walk through their ocean water pool (or other container) filled with chlorine-free water. Allow them to wander about naturally to bathe themselves.

The water dish must be one that they can easily get in and out of, and perhaps has items such as marbles, sea glass, pebbles, piece of cuttlebone or other item that will aid in their safe departure from the water, lest they drown. If you are using the walk through method within your tank and you choose to add Stress Coat with Aloe to the bathing water, make sure to replace any Stress Coat with Aloe-treated water with fresh water after a few hours.

Too Much of a Good Thing

Some people reason that if Stress Coat with Aloe is beneficial to their hermit crabs, why not put it in the water all of the time? Think of Stress Coat with Aloe as a weekly moisturizing treatment. Just as we apply moisturizer to skin that is dry from the effects of salt water from a day at the beach, Stress Coat with Aloe helps to repair the damage to tissues as ‘natures bandage’ as well as create a layer that helps to protect skin from drying out. We do not bathe in moisturizer, nor do we drink it*. Stress Coat with Aloe is not meant for their every day drinking water (fresh is best) it is important to replace with fresh water for the remainder of the day.

Bathing after purchase

If it is the first bath of a hermit crab fresh from a pet store or webstore then you will need to increase the depth of water so that you can do your test for mites at the same time. Always use lukewarm water, de-chlorinated and a drop or two of Stress Coat with Aloe Vera, such as made by Aquarium Pharmaceuticals, although many brands have similar properties. When you think of the conditions the hermit crabs had been in, coupled with dehydration on the trip home, it is common sense to give your hermit crabs a bath on their arrival. You can be sure that after a long, dry journey I would want to go for a nice dip and rehydrate too!

Based on the original article written and Copyrighted by Vanessa Pike-Russell

Want another crabber’s approach to bathing?

Should we change our minds about bathing Hermit Crabs?

Pros and Cons of Bathing by All Things Crabby

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by Stacy

Handling your Hermit Crab

September 27, 2012 in Caresheets

Originally written by Vanessa Pike-Russell

Whether your hermit crabs like to be handled a lot will depend on the nature of the crab’s personality, previous experience with handling and whether it trusts you or not. Whenever handling hermies you should make sure your hands are cleaned before and after interaction, both to prevent the chemicals, oils and perfumes to transfer from you to the hermit crabs, and the potential transfer of contaminated shell water (gunky with foodstuff, wastes etc). We always wash our hands after interactions with dogs, cats, rats, rabbits etc so it is only common sense to do the same with hermit crab.

Holding hermit crab

Holding hermit crab

If your crab trusts you he will come out of his shell and wander over your palm, investigating, smelling and tasting you with antennuelae. It is through their sense of smell that they can recognise you as their carer, their source of food, warmth and happiness.

When you are handling them it is better to do it sitting down in a comfortable position, with a plastic container or ‘play pen’ nearby. This container becomes very handy if you are called away from your hermit crabs but are not ready to put them back in the crabarium. If your crab does fall while handling, the chance of injury is greatly reduced if you are closer to the ground. I have had a hermit crab die because it was dropped from 4 feet up. It is not something that you want to happen, Even if your crab doesn’t perish from the fall, they can learn to distrust humans and dislike handling. Wouldn’t you if you were dropped on your head?

Another precaution to take with hermit crabs is to keep them away from carpet and chemicals. Carpet can dangerous to your hermit crab’s health! The lint, fluff, and wool in your carpet can hurt your crab, drying him out and irritating your crab with the dust mites and other things hidden in carpet, including insecticides and carpet sprinkle which you might put down before vacuuming. Also, hermit crabs tend to grip everything and it can be hard to get them to release their grip on your carpet. If your house has carpet and you want to exercise your crab, you could try using a piece of clean bed sheet or old, clean table cloth. The main thing is that they have some area to explore that is safe from nasties.

Holding hermit crab

Holding hermit crab

I find that it is best to handle my crabs individually, but you can have more than one crab on the sheet if you have quick reflexes. Lay out your palm flat, keep it steady and lower the hermit crab onto your palm. Make sure to put your other palm outstretched next to it in case your crab totters over the edge.

Their sense of sensory perception (being able to judge distances and height) is poor and they will often step out into thin air with more courage than daredevils. You need to keep your eyes on them at all time, as they are expert escape artists and will find the best hiding space in your home if given the chance!

Photo Credit: Travis Wease, Aimee Shuler

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by Stacy

Methods for heating your crabitat

September 25, 2012 in Caresheets

Compilation of information by Vanessa Pike-Russell and Stacy Griffith

To keep your hermit crabs healthy and happy their environment should be kept in optimum temperature and humidity levels. If you are not able to keep the environment stable then your crabs will weaken and become stressed which will lead to death. Hermit crabs are cold blooded creatures and must have a warmish and cooler side to their substrate. If your temperature falls below 72oF on a frequent basis you need a reliable and safe method for heating your crabitat. Whatever type of under tank heater or other heating method you use, it is STRONGLY recommended that you buy a temperature control device such as a thermostat or rheostat. See some examples at the bottom of this page.

Sources of heating suitable for crabariums/crabitats are:
• Under tank heat mats or strips
• Overhead lights
• Heating cables

Note: Heat rocks are not considered safe for hermit crabs!

Here are some examples of suitable products you can use to heat your crabitat. Click the links to read more product info

1. Under-tank heaters

There are many types of under-tank heaters used with reptiles but you need to make sure your crabs do not overheat. The UTH should cover approximately 1/2 of the tanks outside floor. They are sold in a variety of sizes based on your tank size. The best kind are those that keep the temperature stable between 72 (cool side) and 80 degrees F (22-26.67oC) warmer side. Hermit crabs are cold blooded creatures and must have a warmish and cooler side to their substrate.
UTHs can be used on plastic tanks however, plastic tanks are not recommended for use as permanent crabitat!!

Eurorep habistat heat mat diagram

Eurorep habistat heat mat diagram

Reptile heat strip

Reptile heat strip

Heat Strips are manufactured in the same way as mats. They are made narrower and are generally used to heat small boxes and the cages used for housing juvenile snakes and some other species. The principles of use are the same as those for mats and the same precautions should be exercised. In small enclosures the heat build up can be very quick. The temperature should be adequately monitored and controlled with a HabiStat thermostat.
Heat Strips are available in multiple sizes.

Eurorep heat strip

Eurorep heat strip

2. Lights

Lights come in a variety of shapes and sizes. Below are just the common styles to give you some ideas of what is available. Because hermit crabs require a regular cycle of day/night it makes sense to use overhead lights that emit heat. This fills two needs with one item. Reptile bulbs come in day glo and moon glo (with a rare black phosphorus coating) so that you can have warmth at night, which is necessary. The wattage of bulb needed depends on your tank size.

Clamp lights
You will need to switch bulbs from day glo to moon glo or purchase two lamps.

Multi fixture hoods – Available in a variety of lengths

Bi Light Fixture

Pack your reptile’s daytime and nighttime heating all under one hood with this handy light fixture. Reptile terrarium heating and lighting has never been easier. The Bi-Light 2 Reptile Hood Lighting Fixture features two single high-heat ceramic sockets on separate switches and separate power cords and accommodates two incandescent bulbs.

Tri Light Incandescent Fixture

Tri Light

Tri Light

These are more difficult to find now.

Designed exclusively for terrariums, the Tri-Light fixtures feature high-heat porcelain sockets built to withstand the intense heat that is emitted from high-wattage incandescent lamps. A single socket and a double socket on separate switches and cords hold three incandescent lamps up to 150 watts each. The lamps can be plugged into individual timers for both day and night cycling. Available in 30″ size.(6″L x 31″W x 4″H)

Tri Light Combo Fixture

A combination fluorescent and incandescent light fixture designed to maximize the benefits of both types of lamps.
This allows for the use of a full-spectrum, UV-emitting fluorescent lamp along with incandescent full-spectrum daylight/heat lamps and/or incandescent nocturnal/heat lamps. The fixture contains special heat-resistant ceramic sockets for the incandescent lamps and is designed to direct light and heat down into the terrarium. With the combo-light, hobbyists can create an ideal lighting environment for their terrariums.

3. Heat Cable

Greenhouse cable can be a heating alternative for people who are unable or uncomfortable with other sources of heat. Using GHC, however, requires some additional precautions to protect the crabs and yourself. Only use enough cable to cover 2/3 of your tank floor. This allows your crabs to seek out temperature zones for resting and molting underground. Place cable in tank and secure with small strips of heat resistant tape.

Purchase a reptile mat to lay over the cable. This works best if the reptile mat is the same size of your tank floor. Cut a small hole in the corner of your reptile mat and thread the power cord through the hole.
The cord should then be threaded through a piece of PVC pipe that has been cut to fit the height of your tank.
The thermostat should be placed under the reptile mat as well. Crabs can and will cut through rubber and other types of cable insulation. Every part of it must be protected from the crabs.
Once this setup is in place, lay your substrate out on top of the reptile mat and continue with your setup as you normally would.

Check substrate frequently over the next few weeks to confirm that your reptile mat is working correctly
These heating cables speed seedling germination and growth with gentle bottom heat allowing you to get a head start on the growing season. They have a built-in thermostat that automatically activates the heating element if the soil temperature drops below 70 F which is the optimal root zone temperature for most seedlings and starts. Each heating cable includes installation instructions and helpful tips. 110/120 volt electricity required.

Thermostats and Rheostats

Should I use a Rheostat (dimmer) or a Thermostat?

Don’t forget the bulbs!
The wattage and type of bulb you need will vary by fixture and by the size of your crabitat. Day bulbs and night bulbs are needed to maintain a natural light cycle which is vital to successful molting. ARTICLE??