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Stress In Hermit Crabs - Signs, Causes & Treatment

Stress is a real thing, and something all animals and humans experience. Even hermit crabs!


However, in hermit crabs, stress can be lethal. Stress takes a huge toll on a hermit crabs body and can cause all sorts of complications. Below we will cover the common signs of stress in hermit crabs.


Signs -


• Dropping shell and going naked

• Dropping limbs

• Lethargic

• Loss of appetite

• Inactive

• Uncalled for aggression

• Continually retracted inside shell

• Not bathing or drinking


Causes -


●Post Purchase Stress

The moment PPS starts is when a crab is snatched from their wild habitat and then put through the process of being shipped off to pet stores.


It begins when the crab is picked up in the wild and placed into a large bucket or bag along with thousands of other crabs. They are then transported to a warehouse where they will either be forced out of their natural shell into a painted shell or have their natural wild shell painted while they are still in it.


From here, they will then be shipped in a box to various pet stores all over Australia. Upon arrival, they will then be placed into less than ideal pet store tanks with low humidity and heat and fed an unnatural diet that does not support their dietary needs. 90% of pet store crabs will then be purchased by new owners unaware of their proper care needs and placed into another less than ideal tank.

Upwards of 60% of wild crabs taken from the wild will die within the first few months, either during the process at the warehouses, at the pet store or once purchased.


As you can imagine, this causes ALOT of stress on their little bodies. It's an awful ordeal for any animal to go through. This is why most pet store crabs will arrive to you stressed, malnourished and will have a much higher chance of death.


●Continued Handling

Handling of hermit crabs is highly advised against. In some situations, you must handle your crabs. But this should always be done quickly and with minimal amount of stress caused.


Reasons for handling -


• Shell measuring

• Sexing

• Welfare check

• Moving to a new tank

• Emergency situation


Uncalled for handling -


• Taking them out to play and explore

• Taking them outside

• Having a cuddle/pet

• Excessive picking up to check on them

• Handling to take photos for fun

• Bathing them


Excessive, uncalled for handling puts a huge stress on your hermit crabs. They are prey animals and will always see their owners as predators (no matter how nice we are) being continually handled will cause stress in your crabs that they may not be able to come back from. It is highly recommended to keep handling to an absolute minimum to keep your crabs happy and healthy.


●Removing From Tank

Hermit crabs should never be removed from their tank unless it is for a very valid reason.


Reasons for removing from tank -


• Rehoming crabs

• Moving to another tank/iso tank

• An emergency situation such as flooding/ants

• Shell measuring


Reasons that do not validate removing your crab from their tank -


• To play with

• Letting them run around on the floor, couch, bed, outside etc

• Welfare checks (can be done inside the tank)

• Sexing (can be done inside the tank)

• Posing them to take photos

• Taking them out to various places


Not only does removing them from their safe tank cause large amounts of stress on their little bodies, but they will also struggle to breathe without their required heat and humidity.


●Shell Jacking

Shell jacking is when one hermit crab tries to take another hermit crabs shell that they are already occupying. This is an extremely dangerous situation and can often lead to injury and death.


The jacker will attempt to remove the crab from its shell by grasping their limbs and pulling. Sometimes the crab will come out of the shell willingly to prevent injury, but more often than not, they will put up a fight to try and keep their home and this usually ends in ripped off limbs or death.


As you can imagine, this causes a huge amount of stress on the hermit crab who is under attack of having their shell taken.


How to prevent this from occurring -


• Offer an ample amount of suitable shells to your crab's, atleast 6 spare shells per crab that are suitably sized to them.


• Make sure spare shells are of easy access.


• Keep your spare shells clean - give them a wash and soak in marine salt water every month to refreshen them.


• Know your crabs shell mesurements and their preferred openings - D, O, Oval.


●Aggression

As we continually mention, hermit crabs = prey animals. This means they don't sit very highly on the food chain! Being attacked by prey and even other hermit crabs will put your crab into a great deal of stress, as in their mind they are fighting for survival.


Aggression from other crabs will cause stress levels to rise. While dominant behaviour is normal as they assert their place in the pecking order of the tank, uncalled for aggression is where the stress comes into play.


This can include

• Shell jacking

• Attacking and clamping down on other crabs limbs

• Being pulled from their shell


It's important to remember that antennae fights, flicking, pushing and shoving are all normal behaviours between hermit crabs as they assert their place in the hierarchy.


●Low Heat & Humidity

Heat is considered low when it drops below 26.c degrees. While hermit crabs can survive in low temperatures for short periods of time, even these short periods will cause stress upon their bodies.


Anything below 18.c degrees and your crab may be forced into an unnatural hibernation in which they will not return from. It is always recommended to keep their temperatures between 27-32.c degrees all year round, day and night.


Low humidiy will stress your crabs body in a different way to that of heat. We know hermit crabs do not have lungs and that they absorb oxygen through humidity using their modified gills. So what happens when they are exposed to constant low humidity? Their gills will start to dry out and undergo irreversible damage. Low humidy for short bouts of time will not kill them, but being exposed to it often or on a constant basis will begin to damage their gills.


A hermit crabs gills need to stay moist at all times, when exposed to low humidity, they will struggle to breathe and this causes a great amount of physical and emotional stress on them.


●Poor Tank Conditions

Poor tank conditions are one of the most common reasons behind a hermit crabs stress levels. Improper substrate mixture, shallow substrate, no access to deep pools, no enrichment, poor diet, no hiding places, etc can all play a part in stressing out your crab. When crabs go naked or drop limbs due to stress, 90% of the time we see that it is because of the poor tank conditions in which they have been kept.


Make sure that your substrate is atleast 6" deep minimum to offer ample moulting space, deep pools for proper bathing (submerging entire shell), and plenty of enrichment to keep them busy and entertained.


●Drastic Changes To Environment

No one likes change right? Even hermit crabs!

Drastic changes to their environment can cause a lot of fear and stress. Crabs like a stable environment that offers them what they need.


Drastic changes include


• Drastic changes in temperature (going from extremely cold to extremely hot or vice versa) if this is a common occurrence in your tank, it can have a negative effect on their health and overall stress levels. Try to keep a consistent 27-32.c degrees.


• Being moved from one tank to another


• Being removed from their comfortable tank to the outside cold environment in your house or car.


• Constant tank renovations. While redecorating constantly may be fun for us. Doing complete tank revamps every week can upset the balance of your crabs lives. Having someone in their tank continually moving things around and pulling things in and out. It's a scary world when a strange human being is constantly putting their hands in the tank!


• Drastic rise and falls in humidity. Humidity should be kept stable between 70-85%. While humidity above 85% will not harm your crabs, humidity below 70% definitley will. It's best to keep humidity at a stable and safe level to prevent physical stress and damage.



●Being Dug Up

Let's face it, no one likes being kicked out of bed right? We all want to sleep in.


Well the same goes for your hermies. They DO NOT want to be dug up. Digging up a crab and forcing them to the surface is not only extremely dangerous but very stressful for the crab. They have dug down for a reason, it wasn't a mistake. Wether that be to moult, de-stress or just for a fun pass time.


We understand that sometimes we have no other option than to dig them up, especially in an emergency situation such as ant infestation, flooding etc.


But digging up just because you are concerned is not going to go down well for your crab. Not only is this unnecessary handling (which we know causes stress) but you are removing them from a situation that they wanted to be in.


Have faith in your crabs process and they will reappear when they are ready.


●Poor Diet

Our bodies might be able to get away with constant junk food, alcohol and sugar, but for a hermit crab they absolutley will not survive unless they have the correct diet. This actually goes for a lot of animals (captive and wild) did you know that cats need Taurine in their diet otherwise they will go blind? This is why cats can't survive on dog food or vegetables, but dogs can survive on cat food? Crazy right! Same goes for your crab.


They NEED protein, calcium, omega-3 fats, carbohydrates, fibre, carotenoids, plant matter etc to survive. Not only will it fuel their body but it aids in their moulting procedures. And let's face it, they basically just spend their entire lives going through the moulting process! Pre-moult, moult, and post-moult, and then the cycle continues.


Gaps in a hermit crabs diet will often result in them taking extreme measurements to try and fulfill that need. We have seen crabs lacking in protein, often attacking their tank mates and consuming them to fill that void as well as completely breaking down their own shells to try and get calcium, sometimes to the point that the shell is now unusable.


Lack of a balanced and healthy diet will not only cause emotional stress but alot of physical stress on the body.


●Shell Availability

Shells are an absolute necessity in order for hermit crabs to survive, a crab without its shell is a death sentence. Crabs need to keep their soft abdomens moist and protected, and in order to do this, they must wear a shell. But not just any old shell will do.


Shells act as a source of protection from predators and other crabs, when a hermit crab feels threatened, they will retreat inside their shell to protect themselves. However, if the shell is too small, they will not be able to fully retract inside. This is why crabs need to be offered shells that are suitable to their size and needs. A lack of suitable shells will often cause crabs to choose homes that are not suited to them, being either too small or too large. Or worse, they will try and take a shell from another crab. This can cause a lot of emotional stress in your crab as they try to find their perfect home to protect themselves.


●Overcrowding

In the wild, crabs live in large colonies, but we must always remember that they live openly and freely.. this means that they can get away from other crabs if they need too. They can find the perfect moult spot far away from other digging crabs who may possibly find them. Walking hundreds of kilometres a day, crabs have ample space to roam freely.


Now add in captivity and you've got an entirely different ball game. In captivity, there is only so much space for a crab to roam and safely moult, and there are only so many resources available to them. If you overcrowd your tank, crabs are more likely to feel stressed trying to find safe spaces to moult, and gaining access to their essential resources such as shells and food. No one wants to be living on top of eachother and that goes for hermit crabs too.


●Dropping or Shaking Them

Dropping or shaking your crabs is clearly a big no no, and this isn't only because it can cause severe harm. It can also cause a lot of emotional and physical stress on their bodies.


Being a pray animal, any sort of dropping or shaking is going to feel like a threat to them and will instil fear and stress into them.


It is always recommended to only handle your crabs inside the tank or above a soft surface such as a blanket, towel or a tub of moss, and only when they need to be handled.


●Forced Bathing

No one likes being forced to take a bath, and that goes for our little crabby friends too. While some websites or pet stores may tell you that you should bathe your crab daily, the truth is, they will bathe themselves when they need to. It is a natural part of their instincts and they know when and where to bathe.


Forcing them into water is not recommended as this causes them emotional stress. Trust the process and they will bathe when they need too if given deep pools.


Forced bathing into salt and freshwater pools can also alter the water salinity they keep inside their shell. Each crab has their own preferred salinity and will collect salt and fresh water inside their shell to mix their own salinity.


●Forced Shell Alterations

Never try to alter your crabs shell, this is an extremely stressful situation for them and again comes under unnecessary handling.


Forced shell alterations include the following.

• Picking paint off your crabs shell

• Breaking pieces off the shell

• Trying to clean the shell while they are wearing it

• Painting a shell that contains a crab (but please never paint any of your shells, the paint is toxic)

• Scraping, peeling, pulling or cleaning off paint from a crabs shell.


Despite being in a painted shell, your crab will change when they are ready. Your job is to give them suitable shells and their job is to pick one. They know what to do. Trust their process. Sometimes crabs will change within 5 minutes of receiving new shells, and sometimes they hold onto their very inappropriate shell for years. We can't do anything about it other than offering them the correct sized natural shells, some crabs are just stubborn!


●How to reduce a hermit crabs stress levels

While we can't physically tell our crabs to "stress less", there are things we can do to try and help them destress.


• Place them into an environment that is suited to their care needs. This includes deep correct substrate, deep pools, high heat and humidity and offering them a well balanced natural diet to support their health.


• Leaving them alone. It seems kind of obvious, but leave your stressed crabs alone. They need to de-stress on their own. Don't remove them from the tank, dig around for them, play with them, handle them or force them to eat, drink, bathe, or change shells.

All you should be doing is changing the water and food when needed.


• Maintain a stable environment for them with consistent heat and humidity. Avoid unnecessary tank changes, handling, shell measuring, sexing, opening the lid continually etc. Let them relax and calm down in peace.


• Provide a well balanced and healthy diet so that they can get back some of their lost nutrients. You may notice that when stressed they may not eat as often, but you should still offer a variety of foods and they will eat when they are ready.


• Provide them with 12 hours daylight and 12 hours darkness at night. Providing darkness at nightime will help them to feel safer and give them a chance to explore their new surroundings and eat, drink, bathe and change shells under the cover of darkness.


• Provide plenty of dark hiding places within the tank. Stressed crabs will want to hideaway from everyone and everything. If they don't have a safe, dark place to hide and are constantly out in the open, they will feel very insecure and frightened. Being prey animals, they crave safe places to hide away.


●How do I know my crab is destressing?


The number one thing hermit crabs will do to destress is dig down into the substrate. You may notice that when you bring a new crab home, they dig down immediately and you don't see them for weeks on end. You might think they are moulting, but then they pop up and haven't moulted, so what the heck is going on!?


Just like a baby who needs their dummy to calm down, a crab needs to be alone and in the dark to calm themselves. By providing deep substrate, they will dig down and spend weeks down below calming themselves down and relaxing their bodies and minds.

When they are ready, they will reappear ready to explore, eat, drink and bathe.


Sometimes they will go down to destress and will knock off a moult while they are there. This is a double win! But it can take weeks to months to complete because they spend weeks destressing and then weeks to months moulting. This is totally normal and not something to be concerned about.


●How do I know my crab is happy and healthy?

The question we get asked so often! Signs of a happy and healthy crab include.


• Active - your crab is actively exploring their tank, and using their enrichment activities.


• Activity eating and drinking - happy crabs will activitely eat and drink.


• Changing shells - crabs prefer to change shells when they feel secure. Changing Shells means that for a few seconds, they are naked and vulnerable. A healthy, happy and secure crab will have no issues changing their outfit.


• Bathing - happy and healthy crabs will bathe regularly to fill their shell water and clean out their shells.


• Healthy exo appearance - a healthy crab will have a healthy exoskeleton appearance. This includes hairy legs (post moult) colouration of exo (this varies a lot in Aussie crabs), no black spots or sores on the exoskeleton, bright black eyes.


• Moulting regularly - regular successful moults are a great sign of a healthy crab.


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